Animal health monitor device, system and method

Abstract

Animal health monitor device, system and method An animal health monitor device 1 for monitoring the health and / or one or more vital signs of an animal 10 comprises: an attachment means 2 for attaching the animal health monitor device 1 to the animal 10; a sensing means 3 configured to output raw sensor data; and a processing means 4 configured to produce processed output data from the raw sensor data. The sensing means 3 comprises a plurality of contact means for applying an alternating current to the skin of the animal 10 and measuring a voltage across the skin of the animal 10. Each contact means comprises at least one electrode configured for extending through hair or fur. The processed output data comprises at least one output signal indicative of the health and / or one or more vital signs of the animal 10.

Description

[0001] ANIMAL HEALTH MONITOR DEVICE, SYSTEM AND METHOD

[0002] The present application relates to animal health monitor devices and associated systems and methods for monitoring the health and / or one or more vital signs of an animal.

[0003] Background

[0004] Animal owners are increasingly concerned with the health and well-being of the animals in their care. As such, many domestic and working animals now require regular health checks. Such health checks typically involve clinical examinations by professionals and are especially important in ensuring the welfare of elderly animals and the training and monitoring of working and service animals. While clinical examinations by professionals often result in accurate assessments of the health status of an animal, such examinations are labour intensive and provide only a limited snapshot of the health of an animal. While increasing the frequency of such check-ups can help to provide a more accurate and comprehensive picture of overall animal health, the carrying out of such regular examinations can be burdensome and expensive.

[0005] Respiratory rate, heart rate, and heart rate variability are three of the fundamental vital signs used in veterinary medicine to assess the health status of animals. Continuous measurement of such vital signs would be invaluable in revealing an animal’s health, as well as their emotional state in response to stimuli and environmental conditions. However, prior art techniques for measuring these vital signs, such as electrocardiogram and photoplethysmography techniques, have limitations in their application to animals, since many animals have well-insulated skin covered by dense layers of hair, making electrical and physical contact difficult. Animals such as dogs, cows, horses, sheep, etc. have relatively few or no sweat glands and this can result in very high skin-electrode contact impedances, meaning that accurate measurements are difficult and / or impractical. While recently- developed techniques which use radar or acoustic signals to measure animal vital signs address some of these issues, such techniques are susceptible to noise induced by movement. There exists a need for an improved way of monitoring the health and / or one or more vital signs of an animal.

[0006] Summary of the Invention

[0007] According to an aspect of the invention there is provided an animal health monitor device for monitoring the health and / or one or more vital signs of an animal, the animal health monitor device comprising: an attachment means for attaching the animal health monitor device to the animal; a sensing means configured to output raw sensor data, the sensing means comprising a plurality of contact means for applying an alternating current to the skin of the animal and measuring a voltage across the skin of the animal, wherein each contact means comprises at least one electrode configured for extending through hair or fur; and a processing means configured to produce processed output data from the raw sensor data, wherein the processed output data comprises at least one output signal indicative of the health and / or one or more vital signs of the animal. Advantageously, the animal health monitor device can be used to continuously monitor the health and / or one or more vital signs of an animal, for example over extended periods of time.

[0008] Optionally the plurality of contact means comprise dry electrodes. Optionally each contact means comprises at least one resilient electrode. Optionally the or each electrode is configured for extending through the hair or fur of an animal.

[0009] Optionally the or each resilient electrode comprises an elongate resilient member. Optionally the or each elongate resilient member is impregnated with electrically conductive material.

[0010] Optionally the or each electrode comprises an electrically-conductive coating. Optionally the plurality of contact means are suitable for application to the skin of an animal.

[0011] Optionally the plurality of contact means are connected to the attachment means, in use. Optionally the plurality of contact means comprises at least three contact means. Advantageously, three contact means can be applied to the skin of an animal to apply current and measure voltage.

[0012] Optionally the plurality of contact means comprises an array of contact means. Advantageously, the array of contact means can be applied to the skin of an animal. Further advantageously, one or more contact means in the array may be selectable. Optionally the plurality of contact means comprises more than four contact means. Advantageously, a subset of the contact means may be selected for a 3-electrode or a 4-electrode measurement.

[0013] Optionally the processing means comprises a filtering means. Advantageously, the filtering means can be used to filter the raw sensor data and obtain one or more signals that are indicative of the health and / or one or more vital signs of an animal. Optionally the processing means comprises a filtering means configured to obtain the at least one output signal.

[0014] Optionally the filtering means is configured to obtain a first output signal indicative of the respiration of the animal and / or a second output signal indicative of the cardiac activity of the animal.

[0015] Optionally the processing means comprises a filtering means configured to obtain the first output signal by filtering the raw sensor data.

[0016] Optionally the filtering means comprises a high-pass filter.

[0017] Optionally the filtering means comprises a high-pass filter having a cutoff frequency of at least 800 Hz.

[0018] Optionally the filtering means comprises a high-pass filter having a cutoff frequency of up to 6.37 kHz.

[0019] Optionally the filtering means comprises a high-pass filter having a cutoff frequency of 800 Hz, 6.37 kHz, 10 kHz or 25 kHz.

[0020] Optionally the filtering means comprises a demodulator, such as a synchronous demodulator.

[0021] Optionally the filtering means comprises at least one bandpass filter.

[0022] Optionally the filtering means comprises a first bandpass filter and a second bandpass filter.

[0023] Optionally the filtering means comprises a first bandpass filter. Advantageously, the first bandpass filter can be used to isolate a signal that is indicative of the respiration of an animal. Optionally the filtering means comprises a first bandpass filter having a higher cutoff frequency of 0.4-2 Hz.

[0024] Optionally the filtering means comprises a first bandpass filter having a higher cutoff frequency of 0.6 Hz.

[0025] Optionally the filtering means comprises a first bandpass filter having a lower cutoff frequency of 0.01-0.3 Hz.

[0026] Optionally the filtering means comprises a first bandpass filter having a lower cutoff frequency of 0.1 Hz.

[0027] Optionally the filtering means comprises a first bandpass filter having a lower cutoff frequency of 0.01-0.3 Hz and a higher cutoff frequency of 0.4-2 Hz.

[0028] Optionally the filtering means comprises a first bandpass filter having a lower cutoff frequency of 0.1 Hz and a higher cutoff frequency of 0.6 Hz.

[0029] Optionally the processing means is further configured to obtain a second output signal indicative of the cardiac activity of the animal.

[0030] Optionally the filtering means is configured to obtain the second output signal by filtering the raw sensor data.

[0031] Optionally the filtering means comprises a second bandpass filter. Advantageously, the second bandpass filter can be used to isolate a signal that is indicative of the cardiac activity, such as the heart rate, of an animal.

[0032] Optionally the filtering means comprises a second bandpass filter having a lower cutoff frequency of 0.4-2 Hz.

[0033] Optionally the filtering means comprises a second bandpass filter having a lower cutoff frequency of 0.8 Hz.

[0034] Optionally the filtering means comprises a second bandpass filter having a higher cutoff frequency of 3-20 Hz.

[0035] Optionally the filtering means comprises a second bandpass filter having a higher cutoff frequency of 8 Hz.

[0036] Optionally the filtering means comprises a second bandpass filter having a lower cutoff frequency of 0.4-2 Hz and a higher cutoff frequency of 3-20 Hz.

[0037] Optionally the filtering means comprises a second bandpass filter having a lower cutoff frequency of 0.8 Hz and a higher cutoff frequency of 8 Hz.

[0038] Optionally the attachment means comprises a strap. Advantageously, the strap can be used to apply the plurality of contact means / electrodes to the skin of the animal.

[0039] Optionally the strap is a rigid or flexible band. Optionally the attachment means comprises fastening means, such as hook-and- loop fasteners.

[0040] Optionally the attachment means comprises hook-and-loop fasteners.

[0041] Optionally the attachment means comprises a buckle.

[0042] Optionally the attachment means comprises an elasticated band. Advantageously, the elasticated band may be provided in various sizes to accommodate a range of limbs and / or necks of a range of animals.

[0043] Optionally the animal health monitor device further comprises a contact selection means.

[0044] Optionally the contact selection means is configured to determine and / or select a subset of the plurality of contact means.

[0045] Optionally the contact selection means is configured to determine and / or select a plurality of contact means for applying an alternating current to the skin of the animal and measuring a voltage across the skin of the animal.

[0046] Optionally the contact selection means is configured to determine and / or select an optimal plurality of contact means for applying an alternating current to the skin of the animal and measuring a voltage across the skin of the animal. Advantageously, the optimal plurality of contact means may be selected to optimise the measurement of impedance and / or voltage.

[0047] Optionally the contact selection means is configured to analyse the raw sensor data and / or processed output data for a first plurality and a second plurality of contact means.

[0048] Optionally the contact selection means is configured to determine the optimal plurality of contact means based on the analysis of the raw sensor data and / or processed output data.

[0049] Optionally the contact selection means is configured to automatically determine and / or select the optimal plurality of contact means. Advantageously, automatic determination and / or selection of the best contact means set from an array of contact means greater than four removes the need for removal and repositioning of the device to produce an optimal signal.

[0050] Optionally the sensing means further comprises one or more of an accelerometer and a temperature sensor. Advantageously, further sensors can be used to improve the accuracy of the measurement of the conditions of an animal. Optionally the animal health monitor device comprises a communication means. Optionally the animal health monitor device comprises a communication means for sending or reporting the raw sensor data and / or processed output data to one or more further devices.

[0051] Optionally the communication means is a wired communication means. Optionally the communication means is a wireless communication means. Advantageously, the use of a wired or wireless communication means allows sensor data and / or processed output data to be transmitted from the animal health monitor device.

[0052] Optionally the one or more further devices comprise at least a mobile communications device. Advantageously, the mobile communications device can be used to perform further data processing and / or receive user input and / or present data to a user.

[0053] Optionally the one or more further devices comprise at least a server. Advantageously, the server can be used to perform further data processing, for example processing data from a plurality of health monitor devices.

[0054] According to a further aspect of the invention there is provided a system for monitoring the health and / or one or more vital signs of an animal, the system comprising: an animal health monitor device; and one or more further devices in wireless or wired communication with the animal health monitor device, wherein the one or more further devices are configured to receive sensor data and / or processed output data from the animal health monitor device. Advantageously, the system allows the health and / or one or more vital signs of an animal to be monitored and communicated over a network.

[0055] Optionally the animal health monitor device and / or one or more further devices is configured to provide an alarm or notification. Advantageously, the alarm or notification may be indicative of the health and / or one or more vital signs of an animal.

[0056] According to a further aspect of the invention there is provided a method for processing data, the method comprising: receiving raw sensor data from a sensing means, the sensing means comprising at least a plurality of contact means for applying an alternating current to the skin of an animal and measuring a voltage across the skin of the animal; and producing processed output data from the raw sensor data, wherein the processed output data comprises at least one output signal indicative of the health and / or one or more vital signs of the animal. Advantageously, the method can be used to process data indicative of the present health condition of an animal.

[0057] Optionally the method comprises applying a high frequency alternating current to the skin of an animal. Advantageously, the use of a high frequency alternating current ensures that accurate measurements can be made even in the presence of high skin-electrode contact impedances.

[0058] Optionally the method comprises applying an alternating current to the skin of an animal, the alternating current having a frequency of at least 5kHz, for example 50 kHz.

[0059] Optionally producing processed output data comprises: processing the raw sensor data received from the sensing means.

[0060] Optionally producing processed output data comprises: processing raw sensor data received from an impedance sensor.

[0061] Optionally producing processed output data from the raw sensor data comprises: filtering the raw sensor data to obtain a first output signal indicative of the respiration of the animal, wherein the first output signal has a frequency of e.g. between 0.1 Hz and 0.6 Hz; and / or filtering the raw sensor data to obtain a second output signal indicative of the heart rate of an animal, wherein the second output signal has a frequency of e.g. between 0.8 Hz and 8 Hz.

[0062] Optionally producing processed output data comprises: filtering the raw sensor data to obtain a first output signal. Optionally the first output signal has a frequency content of more than 0.01 Hz, or more than 0.1 Hz, or more than 0.3 Hz.

[0063] Optionally the first output signal has a frequency content of less than 2 Hz, or less than 0.6 Hz, or less than 0.5 Hz.

[0064] Optionally the first output signal has a frequency content of between 0.0.1 Hz and 2 Hz.

[0065] Optionally the first output signal has a frequency content of between 0.1 Hz and 0.6 Hz. Optionally producing processed output data from the raw sensor data comprises: filtering the raw sensor data to obtain a second output signal.

[0066] Optionally the second output signal is indicative of the heart rate of an animal.

[0067] Optionally the second output signal has a frequency content of more than 0.4 Hz, or more than 0.8 Hz, or more than 2 Hz.

[0068] Optionally the second output signal has a frequency content of less than 3 Hz, or less than 8 Hz, or less than 20 Hz.

[0069] Optionally the second output signal has a frequency content of between 0.5 Hz and 20 Hz.

[0070] Optionally the second output signal has a frequency content of between 0.8 Hz and 8 Hz.

[0071] Optionally the method further comprises selecting a first plurality of contact means from the array of contact means.

[0072] Optionally the method further comprises applying an alternating current and measuring a voltage using the first plurality of contact means.

[0073] Optionally the method further comprises analysing the raw sensor data output from the first plurality of contact means.

[0074] Optionally the method further comprises selecting a second plurality of contact means from the array of contact means.

[0075] Optionally the method further comprises applying an alternating current and measuring a voltage using the second plurality of contact means.

[0076] Optionally the method further comprises analysing the raw sensor data output from the second plurality of contact means. Advantageously, the method can be used to identify an optimal plurality of contact means for use in a measurement.

[0077] Optionally the sensing means comprises an array of contact means.

[0078] Optionally the method further comprises: selecting a first plurality of contact means from the array of contact means; applying an alternating current and measuring a voltage using the first plurality of contact means; analysing the raw sensor data output from the first plurality of contact means; and selecting a second plurality of contact means from the array of contact means; applying an alternating current and measuring a voltage using the second plurality of contact means; analysing the raw sensor data output from the second plurality of contact means. Advantageously, the method can be used to identify an optimal plurality of contact means for use in a measurement, without necessarily having to move the contact means between measurements.

[0079] Optionally the method further comprises: selecting an optimal plurality of contact means.

[0080] Optionally the method further comprises: selecting an optimal plurality of contact means based on the analysis of the raw sensor data output from the first plurality of contact means and the second plurality of contact means.

[0081] Optionally receiving raw sensor data from the sensing means comprises: receiving raw sensor data from an impedance sensor.

[0082] Optionally receiving raw sensor data from the sensing means comprises: receiving raw sensor data from one or more of an accelerometer and a temperature sensor. Optionally the method further comprises sending or reporting the raw sensor data and / or processed output data to one or more further devices.

[0083] Optionally the method further comprises sending or reporting the raw sensor data and / or processed output data to a mobile communications device or a server.

[0084] According to a further aspect of the invention there is provided an animal health monitor device for monitoring the health and / or one or more vital signs of an animal, the animal health monitor device comprising: a sensing means configured to output raw sensor data; and a processing means configured to produce processed output data from the raw sensor data.

[0085] According to a further aspect of the invention there is provided a system for monitoring the health and / or one or more vital signs of an animal, the system comprising: an animal health monitor device; and one or more further devices in wireless or wired communication with the animal health monitor device.

[0086] According to a further aspect of the invention there is provided a method for processing data, the method comprising: receiving raw sensor data from a sensing means; and producing processed output data from the raw sensor data, wherein the processed output data comprises at least a first output signal indicative of the health and / or one or more vital signs of an animal. Any feature or features described in relation to any aspect, embodiment or example may be combined with any one or more features of any other aspect, embodiment or example.

[0087] Brief Description of the Drawings

[0088] The invention will now be described by way of example only referring to the figures, in which:

[0089] Figure 1 shows a schematic view of an animal health monitor device according to an aspect of the invention.

[0090] Figure 2A shows a side view of an animal health monitor device according to an aspect of the invention.

[0091] Figure 2B shows the animal health monitor device of figure 2A applied to the neck of an animal.

[0092] Figure 3A shows a front view of the animal health monitor of figure 2.

[0093] Figure 3B shows a back view of the animal health monitor of figure 2.

[0094] Figure 4 shows front and side views of an example contact arrangement for use with aspects of the invention.

[0095] Figure 5 shows a schematic view of a bioimpedance measurement setup.

[0096] Figure 6 shows a schematic view of a further bioimpedance measurement setup.

[0097] Figure 7 shows a side view of an animal health monitor device according to an aspect of the invention, applied to the neck of an animal.

[0098] Figure 8 shows a side view of a further animal health monitor device according to an aspect of the invention, applied to the neck of an animal.

[0099] Figure 9 shows a front view of a yet further animal health monitor device according to an aspect of the invention, applied to the neck of an animal.

[0100] Figure 10A shows an attachment arrangement having a plurality of contact arrangements thereon.

[0101] Figure 10B shows the attachment arrangement of figure 10A in an alternative configuration. Figure 11 A shows a further attachment arrangement having a plurality of contact arrangements thereon.

[0102] Figure 11 B shows the further attachment arrangement of figure 11A in an alternative configuration.

[0103] Figure 12 shows a system according to an aspect of the invention, and a plurality of animals.

[0104] Figure 13 shows a method according to an aspect of the invention.

[0105] Figure 14 shows example raw and filtered impedance sensor data, and comparisons with reference ECG data.

[0106] Detailed Description

[0107] In figure 1 there is shown an animal health monitor device 1 according to an aspect of the invention. The animal health monitor device 1 comprises: an attachment arrangement 2 for attaching the animal health monitor device to an animal e.g. a limb or the neck of an animal such as a dog, horse, sheep, cow, cat, etc.; a sensing arrangement 3 configured to output raw sensor data, for example from a plurality of contact arrangements; and a processing unit 4 configured to produce processed output data from the raw sensor data. In the present context, an animal is a nonhuman animal.

[0108] The animal health monitor device 1 facilitates noninvasive and continuous measurements of bioimpedance using multiple dry electrodes. Bioimpedance is modulated noticeably by the act of breathing and the flowing of blood in arteries. The two modulations are separated in frequency, so that those due to breathing can be separated from those due to the heart pumping cycle. Digital signal processing techniques can be used to interpret the raw bioimpedance signal and thus separating respiration and heart rate.

[0109] The animal health monitor device 1 further comprises: a communication module 5 for sending or reporting the raw sensor data and / or processed output data to one or more further devices; a source of electrical power 6, such as a battery; a memory 7 for storing computer instructions, raw sensor data and / or processed output data; and a contact selection unit 8.

[0110] The animal health monitor device 1 is suitable for monitoring the health and / or one or more vital signs of an animal. In examples, the animal health monitor device 1 can be used to monitor the health and / or one or more vital signs of an animal having fur e.g. a dog, horse, sheep, cow, cat, etc. In use, the animal health monitor device 1 can be attached to e.g. the neck of an animal, such as a dog, horse, sheep, cow, cat, etc., for measuring the health and / or one or more vital signs of the animal.

[0111] Figures 2A, 2B, 3A and 3B provide views of the example health monitor 1 according to an aspect of the invention. In this example, the attachment arrangement 2 comprises an elasticated strap 21 . The strap 21 is a flexible band comprising hook- and-loop fasteners. For example, the hook-and-loop fasteners may be provided on part of the strap 21 , for example at one end of the strap 21 . The strap 21 can be wrapped around e.g. a limb or neck of an animal (see e.g. figure 2B), and held securely in place by the hook-and-loop fasteners. In alternative embodiments the strap 21 may include e.g. a buckle for securely attaching the strap 21 to the animal. The strap 21 may be provided in various sizes to accommodate a range of limbs or necks of a range of animals.

[0112] The attachment arrangement 2 is configured for attachment to e.g. a limb or neck of an animal such that at least a part of the sensing arrangement 3 is applied to the skin of the animal. In the example shown in figures 2, 3A and 3B, the animal health monitor device 1 is adapted to be applied around e.g. the neck of a dog which is a comfortable position to allow long-term monitoring to take place. The processing unit 4, communication module 5, battery 6, and memory 7 are provided in a single case, unit or box which is also attached to the strap 21 (see figure 2A). The health monitor device 1 is a standalone portable item that can be attached to, and carried by, the animal being monitored.

[0113] As will be appreciated, the size and / or configuration of the attachment arrangement 2 and strap 21 can be adjusted to allow the animal health monitor device 1 to be attached to other parts of an animal, for example, the forearm or leg of an animal. Furthermore, the strap 21 may allow the animal health monitor device 1 to be attached to the limbs or necks of a range of animals. For example, the strap 21 may be sized to be wrapped around the neck, arm or leg of a particular animal such as a dog, horse, sheep, cow, cat, etc. By ‘neck’ it is meant that portion of the animal between the head and the shoulders. By ‘arm’ it is meant that portion of the animal between the shoulder and e.g. the foot, hand or hoof. By ‘leg’ it is meant that portion of the animal between the hip and e.g. foot or hoof.

[0114] Returning to figure 1 , the animal health monitor device 1 comprises a sensing arrangement 3 configured to output raw sensor data. The sensing arrangement 3 comprises a plurality of n contact arrangements 31 (i.e. 31a to 31 n) for applying a current to the skin of an animal and for measuring a voltage across the skin of said animal. As will be appreciated, in embodiments the number of contact arrangements n may be any suitable number (e.g. 4, 6, 10, 20, 30, >30, etc) and the sensing arrangement 3 may comprise e.g. more than four contact arrangements, more than ten contact arrangements, more than thirty contact arrangements, etc. The sensing arrangement 3 further comprises a current source 32 and a voltage detector 33. The sensing arrangement may further comprise an amplifier unit 34 for amplifying the output of the voltage detector 33 and / or contact arrangements 31. The sensing arrangement 3 can be used for measuring bioimpedance of the skin of an animal. In particular, the sensing arrangement 3 can be used for 3-electrode or 4-electrode measurements of bioimpedance.

[0115] The sensing arrangement 3 comprises a plurality of contact arrangements 31a-31 n attached to the attachment arrangement 2. In examples, the contact arrangements 31a-31 n are in a fixed location on the strap 21. In use, the strap 21 applies / holds the plurality of contact arrangements 31 to the skin or fur of the animal 10, and pushes at least a part of the contact arrangements 31 into contact with the skin of the animal to allow monitoring of the animal.

[0116] Figure 4 shows an example contact arrangement 31 according to an aspect of the invention. Each contact arrangement 31a-31 n shown in figure 1 may be similar or identical to the example contact arrangement 31 shown in figure 4. In examples, the contact arrangement 31 is a multipoint contact electrode. The example contact arrangement 31 comprises a base or housing 35 and a plurality of resilient dry electrodes 36. The contact arrangement 31 may comprise more or fewer resilient dry electrodes 36, for example one resilient dry electrode 36. The base or housing 35 is configured to retain the plurality of dry electrodes 36. Each resilient dry electrode 36 comprises an elongate resilient member 37. Each elongate resilient member 37 is made from a resilient material, such as silicone or rubber. In optional embodiments, each elongate resilient member 37 is impregnated with electrically conductive material. For example, each elongate resilient member 37 may be moulded using a conductive rubber or plastic material. Additionally or alternatively, each elongate resilient member 37 comprises an electrically-conductive coating 38. For example, each elongate resilient member 37 may be at least partially coated in silver paint.

[0117] Each resilient dry electrode 36 is configured for being used to make electrical contact with the skin of an animal, and is configured for extending through hair or fur. In particular, the or each elongate resilient member 37 is sized to extend through hair or fur so that at least a part of the elongate resilient member 37 (e.g. the tip 37a) makes contact with the skin of an animal, in use. The shape and configuration of the resilient dry electrodes 36 allows electrical contact to be made with the skin of an animal, allowing e.g. bioimpedance measurements to be made. As will be appreciated, the resilient and flexible nature of the dry electrodes 36 ensures that a comfortable level of pressure is applied to the skin of the animal, in use.

[0118] The example contact arrangement 31 further comprises an electrical lead or connector 39 which is electrically connected to each of the resilient dry electrodes 36. The electrical lead or connector 39 can be used to electrically connect the resilient dry electrodes 36 to e.g. the other components of the sensing arrangement 3, such as the current source 32 and voltage detector 33, for example via suitable switches.

[0119] Returning to figure 1 , the animal health monitor device 1 comprises a processing unit 4 configured to produce processed output data from the raw sensor data output from the sensing arrangement 3. In examples the processed output data generated by the animal health monitor device 1 comprises a first output signal indicative of the respiration of an animal. Additionally, the processed output data generated by the animal health monitor device 1 comprises a second output signal indicative of the cardiovascular activity of the animal. Furthermore, the processed output data generated by the animal health monitor device 1 can include processed output data and signals from other sensors, such as accelerometers, temperature sensors, electrodermal activity (EDA) sensors and / or electrochemical impedance spectroscopy (EIS) sensors.

[0120] The processing unit 4 comprises a filtering arrangement 41 . The filtering arrangement 41 can be used to analyse the raw sensor data and obtain one or more signals that are indicative of the health and / or one or more vital signs of an animal. The filtering arrangement 41 is configured to obtain output signals by filtering and / or demodulating raw sensor data received from the sensing arrangement 3. The filtering arrangement 41 comprises a first bandpass filter 42, a second bandpass filter 43, a high-pass filter 44 and a synchronised demodulator 46. The various cutoff frequencies of the filters 42, 43 and 44 may be adjusted to be suitable for the particular animal for which the animal health monitor device 1 is being used. The filtering arrangement 41 may be embodied in hardware and / or software.

[0121] The filtering arrangement 41 is configured to obtain the first output signal by filtering the raw sensor data (i.e. the output of the sensing arrangement 3) using the high- pass filter 44, demodulating the output of the high-pass filter 44 using the synchronous demodulator 46, and filtering the resultant demodulated signal using the first bandpass filter 42. Advantageously, the first bandpass filter 42 can be used to isolate a signal that may be analysed to determine the respiration rate of an animal. In examples (see e.g. figure 6), the high-pass filter 44 has a cutoff frequency fcof at least 800 Hz (e.g. 800 Hz, 6.37 kHz, 10 kHz or 25 kHz), and the first bandpass filter 42 has a lower cutoff frequency fi_ of 0.01-0.3 Hz (e.g. 0.1 Hz) and a higher cutoff frequency fa of 0.4-2 Hz (e.g. 0.6 Hz). These cutoff frequencies may be adjusted to be suitable for the particular animal for which the animal health monitor device 1 is being used. The first output signal may be stored in the memory 7. The processing unit 4 is further configured to obtain a second output signal indicative of the cardiac activity of the animal for which the animal health monitor device 1 is being used. The filtering arrangement 41 is configured to obtain the second output signal by filtering the raw sensor data (i.e. the output of the sensing arrangement 3) using the high-pass filter 44, demodulating the output of the high-pass filter 44 using the synchronous demodulator 46, and filtering the resultant demodulated signal using the second bandpass filter 43. The filtering arrangement 41 comprises a second bandpass filter 43 that can be used to isolate a signal that may be analysed to determine the cardiac activity, such as the heart rate, of an animal. In examples (see e.g. figure 6), the high-pass filter 44 has a cutoff frequency fcof at least 800 Hz (e.g. 800 Hz, 6.37 kHz, 10 kHz or 25 kHz), and the second bandpass filter 43 has a lower cutoff frequency fi_ of 0.4-2 Hz (e.g. 0.8 Hz) and a higher cutoff frequency of 3- 20 Hz (e.g. 8 Hz). These cutoff frequencies may be adjusted to be suitable for the particular animal for which the animal health monitor device 1 is being used. The second output signal may be stored in the memory 7.

[0122] The processing unit 4 comprises an analysis unit 49. The analysis unit 49 is configured to process, analyse and interpret the filtered waveforms i.e. the output(s) of the filtering arrangement 41. For example, the analysis unit 49 may be used to determine respiration rate and / or heart rate of an animal based on the outputs of the first and / or second bandpass filters 42,43. Furthermore the analysis unit 49 may be used to monitor changes in the output of the first bandpass filter 42 and / or second bandpass filter 43 over time. For example, the analysis unit 49 may be used to determine respiratory rate, heart rate and heart rate variability and / or abnormal or meaningful changes in respiratory rate, heart rate and heart rate variability. The analysis unit 49 may be used in the derivation of arrhythmias from the raw bioimpedance signal. As will be appreciated, the analysis unit 49 may be part of the processing unit 4 and local to the animal health monitor device 1 . In optional embodiments, the analysis unit 49 may be remote from the animal health monitor device 1 and may be located for example in a remote server, such as an RF-linked server.

[0123] The principle of measuring bioimpedance will now briefly be explained with reference to figures 5 and 6. Figure 5 shows a current source 32 (current drive) connected to two driving contact arrangements 31 a, 31 d, and a voltage detector 33 connected to two measuring contact arrangements 31 b,31 c. Each of the contact arrangements 31 is in contact with the skin 12 of an animal 10. The driving contact arrangements 31 a, 31 d are used to apply an alternating current (e.g. a 0.1 mA pk-pk, 50 kHz signal) to the skin 12 of the animal 10, while the voltage detector 33 is configured to measure an associated potential difference between the two measuring contact arrangements 31 b, 31 c, which are also applied to the skin 12 of the animal 10. The use of a high frequency alternating current ensures that accurate measurements can be made even in the presence of high skin-electrode contact impedances, removing the need to use e.g. gels to reduce contact impedance. Assuming that the peak-to-peak (pk-pk) amplitude of the driving current is constant, the voltage measured by the voltage detector 33 is proportional to the impedance of underlying body tissue. As is explained in further detail below, bioimpedance varies with respiratory and cardiac activity, and can be used to infer e.g. the breathing rate and heart rate of the animal 10.

[0124] As will be appreciated, figure 5 shows an example of a four-point measurement. Three-point measurements can be achieved by combining two of the contact arrangements, so that one contact arrangement (e.g. 31 a) is both a driving contact (i.e. connected to the current source 32) and a measuring contact (i.e. connected to the voltage detector 33 also), while two other contact arrangements (e.g. 31 c,31 d) are connected to the other terminals of the current source 32 and voltage detector 33, respectfully. Three-point measurements are dominated by skin impedance under the combined current / voltage electrode, which makes detection of variations due to respiration or cardiac activity difficult. However, three-point measurements can be used to enhance stress estimation using the change in skin impedance.

[0125] The signal measured by the voltage detector 33 comprises a plurality of frequency components, including both bioimpedance signals as well as lower-frequency signals, which may include noise. Thus, a plurality of distinct signals can be received at the voltage detector 33 from the two voltage measurement contact arrangements 31 b, 31 c. The typical frequencies of bioimpedance signals are in the range of 5 kHz - 1 MHz, while significant noise signals may be present below 5 kHz. Bioimpedance signals can be isolated using a high-pass filter above 800 Hz. As is explained in further detail below, where multiple contact arrangements are available, it may be advantageous to select optimal contact arrangements for measuring bioimpedance.

[0126] Figure 6 shows in detail an arrangement for measuring bioimpedance. Figure 6 shows a current source 32 (current drive) connected to two driving contact arrangements 31 a, 31 d, and an amplifier 34 connected to two measuring contact arrangements 31 b, 31 c. Each of the contact arrangements 31 is in contact with the skin 12 of an animal 10. The driving contact arrangements 31 a, 31 d are used to apply an alternating current (e.g. a 0.1 mA pk-pk, 50 kHz signal) to the skin 12 of the animal 10, while the amplifier 34 is configured to output a signal which is proportional to the potential difference between the two measuring contact arrangements 31 b, 31 c, which are also applied to the skin 12 of the animal 10. The use of a high frequency alternating current ensures that accurate measurements can be made even in the presence of high skin-electrode contact impedances, removing the need to use e.g. gels to reduce contact impedance. The output of the amplifier 34 is provided to the processing unit 4. Figure 6 shows only the filtering arrangement 41 of the processing unit 4; the other components of the processing unit 4 have been omitted from this figure, for clarity.

[0127] As shown in figure 6, the signal received by the processing unit 4 from the amplifier 34 is provided to the high-pass filter 44. This arrangement allows the separation of high-frequency bioimpedance signals from lower-frequency signals, which may include noise. The output of the high-pass filter 44 is input to a synchronous demodulator 46, which is synchronised to the current source 32. The synchronous demodulator 46 is used to extract the amplitude and phase of the changing BioZ measurement from the filtered output of the high-pass filter 44. The output of the synchronous demodulator 46 is provided in parallel to the first bandpass filter 42 and the second bandpass filter 43. The outputs of the first and second bandpass filters 42, 43 may be provided as outputs from the filtering arrangement 41 / processing unit 4, and optionally may be provided to e.g. the analysis unit 49 for further processing. In use, the filtering arrangement 41 allows a plurality of signals, each of which may be indicative of the health and / or vital signs of an animal, to be measured using the sensing arrangement 3. In the example of figure 6, the filtering arrangement 41 provides a first signal (“Respiration Signal (BioZ)”) that is indicative of the respiration of an animal, a second signal (“Heart Signal (BioZ)”) that is indicative of the cardiac activity, such as the heart rate, of an animal.

[0128] Figures 7 to 9 show illustrative examples of contact arrangements 31 that have been applied to the neck 11 of an animal 10. The contact arrangements 31 are similar to the example shown in figure 4. The contact arrangements 31 form part of a sensing arrangement 3 of an animal health monitor device 1 and are attached to the attachment arrangement 2 of the animal health monitor device 1 . The other components of the animal health monitor device 1 have been omitted from this figure, for clarity.

[0129] In the examples of figures 7 to 9, the contact arrangements 31 are applied to the neck 11 of an animal 10 in a variety of orientations, including transverse orientations (i.e. perpendicular or substantially perpendicular to the axis of the neck, as shown in figures 7 and 9) and longitudinal orientations (i.e. parallel or substantially parallel to the axis of the neck, as shown in figure 8), among others. Varying the position and orientation of the contact arrangements on the neck 11 of the animal 10 will result in the contact arrangements 31 being closer to or further from e.g. the common carotid arteries 701 of the animal 10, which will in turn affect the signal-to-noise ratio of the measurements.

[0130] In use, the strap 21 applies / holds the plurality of contact arrangements 31 to the skin or fur of the animal 10, and pushes at least a part of the contact arrangements 31 into contact with the skin of the animal to allow monitoring of the animal via bioimpedance measurements. In use, the or each elongate resilient member 37 of each contact arrangement 31 extends through the hair or fur of the animal 10 so that at least a part of the elongate resilient member 37 (e.g. the tip 37a) makes contact with the skin of an animal. As will be appreciated, the resilient and flexible nature of the dry electrodes 36 of each contact arrangement 31 ensures that a comfortable level of pressure is applied to the skin of the animal, in use. In the setups shown in figures 7 to 9, the quality of the measured signal will change depending on the locations of the contact arrangements. Finding the optimal arrangement of contacts typically involves individually moving the contact arrangements 31 to different locations on the animal and repeatedly measuring the corresponding output signal, to compare with previous results. As will be appreciated, such a scheme can be laborious and time consuming. To solve such problems the example animal health monitor devices of figures 7 to 9 comprise sensing arrangements 3 attached to the attachment arrangement 2. The contact arrangements 31 can be easily applied to the skin of an animal in a range of positions, and can be moved to different positions by moving the entire attachment arrangement 2.

[0131] To provide further flexibility in the choice and arrangement of contact arrangements 31 , the health monitor device 1 comprises a contact selection unit 8. The contact selection unit 8 is configured to determine and / or select a subset of the plurality of contact arrangements 31 for use in bioimpedance measurements. The contact selection unit 8 is configured to determine and / or select an optimal plurality of contact arrangements 31 for applying an alternating current to the skin of the animal and measuring a voltage across the skin of the animal. Advantageously, the optimal plurality of contact arrangements 31 may be selected to optimise the measurement of impedance and / or voltage.

[0132] In an example, the contact selection unit 8 is configured to analyse the raw sensor data and / or processed output data for at least a first plurality of contacts and a second plurality of contacts. Additional pluralities of contact arrangements, for example a third plurality of contact arrangements, may be included in the analysis. The contact selection unit 8 is configured to determine the optimal plurality of contact arrangements 31 based on the analysis of the raw sensor data and / or processed output data. While the contact selection unit 8 is shown in figure 1 as being separated from the processing unit 4 for clarity, in some embodiments the contact selection unit 8 and the processing unit 4 may be combined into a single unit. Figures 10 and 11 show further illustrative examples of sensing arrangements 3 (in particular contact arrays) that may be employed in the animal health monitor device 1 . Each sensing arrangement 3 comprises a plurality of contact arrangements 31 that may be applied to the skin of an animal to apply an alternating current and measure a voltage response signal. In figures 10 and 11 , example arrays of contact arrangements 31 are shown in relation to their positions on the attachment arrangement 2, to which the contact arrangements 31 are attached, in use. For clarity, other features of the animal health monitor device 1 are not shown in these figures.

[0133] Figure 10 shows an example contact arrangement array 1000 comprising sixteen contact arrangements 31 . The contact arrangements 31 of this embodiment are provided equally spaced along an axis (i.e. the longest axis) of the attachment arrangement 2. In use, the attachment arrangement 2 is wrapped around the neck of an animal such that at least a part of the contact arrangements 31 make contact with the skin 12 of the neck 11 of the animal 10. In use, the contact arrangements 31 will be spaced circumferentially around the neck 11 of the animal 10, in a situation analogous to that shown in figure 7. To find the optimal position for applying current / measuring voltage (i.e. the position where the measured signal is strongest and / or the signal-to-noise ratio is largest), the contact arrangement array 1000 can be moved around the neck by adjusting the position of the animal health monitor device 1 / attachment arrangement 2 on the neck 11 of the animal 10. For example, the attachment arrangement 2 can be moved closer to or further from the head of the animal, or can be rotated around the neck 11 of the animal 10.

[0134] Furthermore, the contact arrangements 31 in the contact arrangement array 1000 are individually selectable so that, in use, current can be applied to any pair of contact arrangements in the array and voltage can be measured between any other pair of contact arrangements in the array. For example, the contact selection unit 8 can initially select one set of contact arrangements according to a first measurement configuration (Figure 10A) and subsequently the contact selection unit 8 can select a second set of contact arrangements according to a second measurement configuration (Figure 10B). This allows a comparison to be made between the signal measured using one set of contact arrangements vs the signal measured using another set of contact arrangements, to find an optimal configuration which provides the strongest signal or greatest signal-to-noise ratio. As will be appreciated, having more than four contact arrangements 31 in the array 1000 allows such a comparison to be made without necessarily having to move the position of the animal health monitor device 1 on the neck of the animal.

[0135] Figure 11 shows another example contact arrangement array 1100 comprising sixteen contact arrangements 31. The contact arrangements 31 of this embodiment are provided in four groups of four. Each contact arrangement in a single group is spaced along an axis (i.e. the shortest axis) of the attachment arrangement 2. Each group is spaced from a neighbouring group along another axis (i.e. the longest axis) of the attachment arrangement 2. In use, the attachment arrangement 2 is wrapped around the neck of an animal such that at least a part of the contact arrangements 31 make contact with the skin 12 of the neck 11 of the animal 10. Each of the contact arrangements 31 within a single group will be spaced longitudinally along the neck 11 of the animal 10, in a situation analogous to that shown in figure 8, while neighbouring groups of contact arrangements will be spaced circumferentially around the neck 11 of the animal 10, in a situation analogous to that shown in figure 7.

[0136] To find the optimal position for applying current / measuring voltage (i.e. the position where the measured signal is strongest and / or the signal-to-noise ratio is largest), the contact arrangement array 1100 can be moved around the neck by adjusting the position of the animal health monitor device 1 / attachment arrangement 2 on the neck 11 of the animal 10. For example, the attachment arrangement 2 can be moved closer to or further from the head of the animal, or can be rotated around the neck 11 of the animal 10.

[0137] Furthermore, the contact arrangements 31 in the contact arrangement array 1100 are individually selectable so that, in use, current can be applied to any pair of contact arrangements in the array and voltage can be measured between any other pair of contact arrangements in the array. For example, the contact selection unit 8 can initially select one set of contact arrangements according to a first measurement configuration (Figure 11A) and subsequently the contact selection unit 8 can select a second set of contact arrangements according to a second measurement configuration (Figure 11 B). This allows a comparison to be made between the signal measured using one set of contact arrangements vs the signal measured using another set of contact arrangements, to find an optimal configuration which provides the strongest signal or greatest signal-to-noise ratio. As will be appreciated, having more than four contact arrangements 31 in the array 1100 allows such a comparison to be made without necessarily having to move the position of the animal health monitor device 1 on the neck of the animal.

[0138] Dependent on the physiology of the subject, optimum contact arrangement combinations may not be in a longitudinal line or transverse column for bioimpedance acquisition; the contact selection mechanism may allow for independent selection of any suitable combination of the relevant contact arrangements. The contact selection mechanism may for example use an array of switches that can selectively connect the contact arrangements to the current source 32 and voltage detector 33 or amplifier 34. Figure 11 B provides an example selection of a plurality of contact arrangements that are not in a longitudinal line or transverse column.

[0139] Figure 12 shows a system 1200 for monitoring the health and / or one or more vital signs of one or more animals 10, 10a according to an aspect of the invention. The system 1200 comprises: an animal health monitor device 1 ; and one or more further devices 1202 in wireless or wired communication with the animal health monitor device 1 . The one or more further devices 1202 are configured to receive sensor data and / or processed output data from the animal health monitor device 1 . The system 1200 allows the health and / or one or more vital signs of one or more animals to be monitored and communicated over a network. As shown in figure 12, the one or more further devices 1202 are in wireless or wired communication with the animal health monitor device 1a which has been applied to the neck of a further animal 10a. The animal health monitor device 1a of the further animal 10a is similar to the animal health monitor device 1 of the animal 10.

[0140] In the example of figure 12 the communication arrangement of the animal health monitor device 1 is a wireless communication arrangement, for example via Bluetooth or WiFi (e.g. for short-range communication) or LoRa (e.g. for longer- range communication), allowing raw sensor data and / or processed output data from the animal health monitor device 1 to be transferred wirelessly to the one or more further devices 1202. In alternative embodiments, the communication arrangement of the animal health monitor device 1 may be a wired communication arrangement, wherein one or more communication wires extend from the animal health monitor device 1 to the one or more further devices 1202 for data communication via a wire.

[0141] The one or more further devices 1202 comprise at least a mobile communications device and / or a server in wireless communication with the animal health monitor device 1 . The mobile communications device or server can be used to perform further data processing, for example processing data from a plurality of health monitor devices 1. In some examples, the animal health monitor device 1 and / or one or more further devices 1202 can be configured to provide an alarm or notification which may be indicative of the health and / or one or more vital signs of an animal 10,10a.

[0142] Figure 13 discloses a method 1300 for processing data according to an aspect of the invention. The method 1300 can be carried out by the animal health monitor device 1. The method 1300 comprises: applying a sensing arrangement to a limb or neck of an animal (step 1301); receiving raw sensor data from the sensing arrangement (step 1304); and producing processed output data from the raw sensor data (step 1306). Optionally, the method further comprises: selecting a sensing arrangement configuration (step 1302) and transmitting the raw or processed output data (step 1308). Advantageously, the method 1300 can be used to process data indicative of the present health condition and / or vital signs of an animal, and is suitable for longterm animal health monitoring.

[0143] At step 1301 , the method 1300 comprises applying the animal health monitor device 1 to a limb or neck of an animal. For example, the animal health monitor device 1 may be attached to the neck, arm, chest, forearm or leg of an animal such as a dog, horse, sheep, cow, cat, etc. In preferred embodiments at step 1301 the animal health monitor device 1 may be applied to the neck of a mammal, such as a dog, horse, sheep, cow, cat, etc., by wrapping the strap 21 of the attachment arrangement 2 around the neck of the animal and securing the animal health monitor device 1 in place using a fastening arrangement, such as the hook-and-loop fasteners of the strap 21 . The animal health monitor device 1 may be applied to the limb or neck of the animal such that the resilient dry electrodes 36 of the contact arrangements 31 make electrical contact with the skin of the animal. In use, the resilient dry electrodes 36 may extend through the hair or fur of the animal.

[0144] At step 1302, the method 1300 comprises selecting a sensing arrangement configuration. The sensing arrangement 3 of the animal health monitor device 1 comprises at least a plurality of contact arrangements 31 for applying an alternating current to the skin of an animal and measuring a voltage across the skin of the animal. Step 1302 may be carried out by the contact selection module 8 of the animal health monitor device 1.

[0145] Where the sensing arrangement 3 comprises exactly four contact arrangements, step 1302 involves selecting those four contact arrangements by the contact selection unit 8. Considering the example of figure 7, the outer two contact arrangements 31 a, 31 d of an array of contact arrangements may be selected as the current contact arrangements (denoted ‘C’) and the inner two contact arrangements 31 b, 31 c selected as the voltage measurement contact arrangements (denoted ‘V’). Alternatively, three contact arrangements may be chosen if a three-point measurement scheme is to be used.

[0146] Where the sensing arrangement comprises more than four contact arrangements, step 1302 involves selecting a subset of the plurality of contact arrangements by the contact selection unit 8. Considering the example contact arrangement array 1000 of figure 10A, opposing contact arrangements 31 a, 31 d in the array 1000 may be selected as the current contact arrangements and two further contact arrangements 31 b, 31 c located between the current contact arrangements 31 a, 31 d may be selected as the voltage contact arrangements. Alternatively, three contact arrangements may be chosen if a three-point measurement scheme is to be used.

[0147] The contact selection unit 8 can be configured to determine and / or select, at step

[0148] 1302, an appropriate subset of the plurality of contact arrangements for applying an alternating current to the skin of the animal and for measuring a voltage across the skin of the animal. An optimal plurality of contact arrangements can be selected to optimise the measurement of impedance and / or voltage. The contact selection unit 8 can be configured to determine and / or select, at step 1302, a set of four contact arrangements that will provide raw sensor data having the strongest signal and / or largest signal-to-noise ratio during a continuous bioimpedance measurement. The contact selection unit 8 can be configured to automatically determine and / or select the optimal plurality of contact arrangements. Advantageously, automatic determination and / or selection of the best contact set from an array of contact arrangements greater than four removes the need for removal and repositioning of the animal health monitor device 1 to produce an optimal signal(s).

[0149] For example, as part of step 1302, the method 1300 may include selecting a first plurality of contact arrangements from the array of contact arrangements. For example, the contact arrangement array shown in figure 10A may be selected by the contact selection unit 8. The raw sensor data output from the first plurality of contact arrangements may then be analysed. A second plurality of contact arrangements from the array of contact arrangements may then be selected. For example, the contact arrangement array shown in figure 10B may be selected by the contact selection unit 8. The raw sensor data output from the second plurality of contact arrangements may then be analysed. By comparing the raw sensor data output from the first plurality of contact arrangements with the raw sensor data output from the second plurality of contact arrangements, an optimal plurality of contact arrangements can be identified, without necessarily having to move the position of the animal health monitor device 1 on the neck of the animal. For example, if the raw sensor data measured using the first plurality of contact arrangements has a larger signal or larger signal-to-noise ratio than the raw sensor data measured using the second plurality of contact arrangements, then the first plurality of contact arrangements can be determined as the optimal set of contact arrangements.

[0150] The first and second pluralities of contact arrangements may be chosen by the contact selection unit 8 at random or may be chosen in a specific order. For example, a specific order may be saved in the memory 7 and accessed by the contact selection unit 8. The contact selection unit 8, when identifying the optimal set of contact arrangements, may carry out measurements using further (e.g. third, fourth, fifth) pluralities of contact arrangements, and may carry out measurements for all possible combinations of contact arrangements in the contact arrangements array. The combinations tested may be limited to those in which the contact arrangements selected for measuring voltage are between the contact arrangements selected for applying current.

[0151] As will be appreciated, the contact arrangement arrays 1000 and 1100 are particularly advantageous, since they allow a wide variety of configurations to be tested, and allow comparisons to be made between e.g. longitudinally-spaced arrangements of contact arrangements (figure 11A), circumferentially spaced arrangements of contact arrangements and other arrangements (figure 11 B).

[0152] The optimal set of contact arrangements can be selected at step 1302, and the raw sensor data received at step 1304 may correspond to raw sensor data collected using the optimal set of contact arrangements.

[0153] At step 1304, the method 1300 comprises receiving raw sensor data from the sensing arrangement. Considering the example of figure 6, the raw sensor data received at step 1304 may correspond to e.g. the direct output of the measuring contact arrangements 31 b, 31 c, the output of the amplifier 34, and / or the filtered and demodulated output of the synchronised demodulator 46.

[0154] At step 1306, the method 1300 comprises producing processed output data from the raw sensor data. In particular, step 1306 comprises filtering the raw sensor data to provide a plurality of signals indicative of the condition of an animal. Step 1306 may be carried out by a processing unit, for example the processing unit 4 of the animal health monitor device 1 . Alternatively, a further device may receive and process the raw sensor data from the sensing arrangement 3 of the animal health monitor device 1.

[0155] Figure 14 provides an illustrative example of producing processed output data from raw sensor data. Figure 14 also shows reference ECG data, for comparison. Panel A of figure 14 shows example raw impedance sensor data 1400 received from the sensing arrangement 3 / processing unit 4. In this example, the raw impedance sensor data 1400 corresponds to the filtered and demodulated output of the synchronised demodulator 46 shown in figure 6. The raw sensor data 1400 is a timevarying impedance signal measured using the sensing arrangement of the animal health monitor 1 . The raw sensor data 1400 is raw impedance sensor data, i.e. it is an example of the output of the demodulator 46 shown in figure 6. The example impedance signal 1400 is a measurement of the bioimpedance of the limb or neck of an animal. The example impedance signal 1400 comprises a plurality of frequency components. The impedance signal 1400 includes at least a lower-frequency component which is indicative of respiratory activity, and a higher-frequency component indicative of cardiac activity.

[0156] Panel A of figure 14 further shows an ECG reference signal 1410. The ECG reference signal 1410 has been measured on the same animal and at approximately the same time as the raw sensor data 1400. The ECG reference signal 1410 is a typical ECG waveform and includes peaks (e.g. 1410a) corresponding to electrical activity of the heart of the animal, the time difference between consecutive peaks corresponding to the heart rate of the animal.

[0157] Panel B of figure 14 shows a first signal 1402 that has been isolated from the raw sensor data 1400 by a first bandpass filter 42. In this example, the first bandpass filter 42 has a lower cutoff frequency of 0.1 Hz and a higher cutoff frequency of 0.5 Hz. The resultant signal, i.e. a first output signal 1402, has a frequency component that is the same as the frequency of the respiration of the animal. The signal 1402 output from the first bandpass filter 42 has a frequency of approximately 15 breaths per minute.

[0158] Panel C of figure 14 shows a second, higher frequency, signal 1404 that has been isolated from the raw sensor data 1400 by the second bandpass filter 43. In this example, the second bandpass filter 43 has a lower cutoff frequency of 0.7 Hz and a higher cutoff frequency of 3 Hz. The resultant signal, i.e. the second output signal 1404, has a frequency component that is the same as the frequency of the heart rate of the animal. The signal output from the second bandpass filter has a frequency of approximately 51 beats per minute.

[0159] Panel C of figure 14 also shows the ECG reference signal 1410 having peaks 1410a, the time difference between consecutive peaks corresponding to the heart rate of the animal. The second signal 1404 also includes peaks 1404a. As will be appreciated, the peaks 1404a in the second signal 1404, measured using bioimpedance techniques, correspond to the peaks 1410a in the ECG reference signal 1410. The correspondence between the peaks in the second signal 1404 and the ECG reference signal 1410 demonstrates that the second signal 1404 (and more generally the raw impedance sensor data 1400) can be used to determine the heart rate of the animal using the techniques described herein.

[0160] In examples, the second signal 1404 can be used to determine heart rate variability for the animal. Heart rate variability provides information about fluctuations in the time between heartbeats. For example, panel C of figure 14 shows multiple heartbeat cycles (e.g. 1405a-1405b), there being variations in the length of each cycle. In a given time period, the heart rate variability is the difference between the longest cycle and the shortest cycle. From the measured heart rate variability, it is possible to estimate stress of the animal. A low heart rate variability (e.g. heart rate variability of less than 10 ms) may indicate that the animal is in a stressed state. A high heart rate variability (e.g. heart rate variability of at least 10 ms) may indicate that the animal is not in a stressed state. Furthermore, heart rate variability can be used to detect arrythmias. An arrythmia is an irregular heart rhythm. The heart may beat too quickly, too slowly, or with irregular rhythm. An arrythmia can be inferred from an irregularly large variation in beat-to-beat interval from an extracted heart rate bioimpedance signal.

[0161] In an example, we consider the two cycles 1405a and 1405b shown in panel C of figure 14. Based on peak-peak measurements, the length of a first example cycle 1405a, which is the longest cycle in this period, is 1.17 s and the length of a second example cycle 1405b, which is the shortest cycle in this period, is 0.72 s. The heart rate variability in the time period covering the example cycles 1405a-1405b is 1.17- 0.72 s = 0.45 s. The processing unit 4 of the health monitor 1 , particularly the analysis unit 49, may be configured to determine heart rate variability from the second signal 1404. The processing unit 4 / analysis unit 49 may classify an animal as being in a stressed state when their heart rate variability, measured over a predetermined time period (e.g. the last 1 minute) is lower than a threshold (e.g. 10 ms). When the processing unit 4 / analysis unit 49 classifies an animal as being in a stressed state, an alarm or notification may be provided.

[0162] The processing unit 4 of the health monitor 1 , particularly the analysis unit 149, may be configured to determine recovery time from e.g. the first signal 1402 and / or the second signal 1404. By recovery time it is meant the time taken for a measured health and / or vital sign to return to a normal level. For example, where an animal has a heart rate which is normally within the range of 40-60 beats per minute, the recovery time corresponds to the amount of time it takes for the measured heart rate of the animal to change from a peak rate (e.g. 120 beats per minute) to being within the normal range (i.e. 60 beats per minute or below).

[0163] Returning to figure 13, at step 1308 the method 1300 comprises transmitting the raw or processed output data, for example to a further device of the one or more further devices 1202 shown in figure 12. The one or more further devices may include a mobile communications device or a server. Step 1308 may be carried out by a communication module, for example the communication module 5 of the animal health monitor device 1 .

[0164] Step 1308 may further include determining one or more quantities using the processed output data. For example, the analysis unit 49 may use the signal that has been isolated from the raw sensor data 1400 by the second bandpass filter 43 to determine heart rate variability of the animal.

[0165] At step 1308, the method may additionally or alternatively comprise transmitting an alarm or notification to a further device, for example one or more of the further devices 1202 shown in figure 12. The processing unit 4 may be used to monitor the first output signal 1402 or second output signal 1404. For example, the processing unit 4 may compare the first output signal 1402 and / or second output signal 1404 with one or more thresholds. When the frequency of the first output signal 1402 and / or frequency of the second output signal 1404 falls below a predetermined threshold, the processing unit 4 may generate an alarm or notification. In an illustrative example, the processing unit 4 may compare the frequency of the first output signal 1402 with a threshold frequency. When the frequency of the first output signal 1402 falls below the threshold frequency, this may indicate that an animal has stopped breathing, or that their breathing rate has fallen below a safe level. In this example, the processing unit 4 may generate an alarm or notification indicating that the animal’s breathing is irregular and should be checked. Alternatively or additionally, the processing unit 4 may determine heart rate variability from the second signal 1404. In examples, the processing unit 4 may determine heart rate variability using data measured over the last minute or the last 5 minutes etc. and may compare this determined heart rate variability with a predetermined threshold (e.g. 0.1 ms). When the determined heart rate variability falls below the predetermined threshold, the processing unit 4 may identify the animal as being in a stressed state and may generate an alarm or notification. As will be appreciated, the analysis and generation of a notification or alarm may be carried out at a further device, for example one or more of the further devices 1202 shown in figure 12.

[0166] As will be understood by the skilled person, the example embodiments presented above can be modified in a number of ways without departing from the scope of the invention. For example, any of the sensing arrangements may further comprise one or more of an accelerometer and a temperature sensor. For example, the accelerometer may be a multi-axis accelerometer, to indicate the level of exercise or movement of the animal or subject, and the temperature sensor may be used to measure the skin temperature of the animal or subject. Data measured by the accelerometer and / or temperature sensor may be combined with other data measured by the animal health monitor device. Advantageously, further sensors can be used to improve the accuracy of the measurement of the conditions of an animal. In addition, further interpretation may be applied to one or more signals to determine further aspects of the subject's condition, for example stress or physical exercise. The features disclosed in the foregoing description or the following drawings, expressed in their specific forms or in terms of an arrangement for performing a disclosed function, or a method or a process of attaining the disclosed result, as appropriate, may separately, or in any combination of such features be utilised for realising the invention in diverse forms thereof.

Claims

CLAIMS1 . An animal health monitor device for monitoring the health and / or one or more vital signs of an animal, the animal health monitor device comprising: an attachment means for attaching the animal health monitor device to the animal; a sensing means configured to output raw sensor data, the sensing means comprising a plurality of contact means for applying an alternating current to the skin of the animal and measuring a voltage across the skin of the animal, wherein each contact means comprises at least one electrode configured for extending through hair or fur; and a processing means configured to produce processed output data from the raw sensor data, wherein the processed output data comprises at least one output signal indicative of the health and / or one or more vital signs of the animal.

2. An animal health monitor device according to claim 1 , wherein each contact means comprises at least one resilient electrode.

3. An animal health monitor device according to claim 2, wherein the or each resilient electrode comprises an elongate resilient member.

4. An animal health monitor device according to claim 3, wherein the or each elongate resilient member is impregnated with electrically conductive material.

5. An animal health monitor device according any preceding claim, wherein the or each electrode comprises an electrically-conductive coating.

6. An animal health monitor device according to any preceding claim, wherein the processing means comprises a filtering means configured to obtain the at least one output signal.

7. An animal health monitor device according to claim 6, wherein the filtering means is configured to obtain a first output signal indicative of the respirationof the animal and / or a second output signal indicative of the cardiac activity of the animal.

8. An animal health monitor device according to claim 6 or claim 7, wherein the filtering means comprises a first bandpass filter having a lower cutoff frequency of 0.01-0.3 Hz, for example 0.1 Hz, and a higher cutoff frequency of 0.4-2 Hz, for example 0.6 Hz.

9. An animal health monitor device according to any one of claims 6 to 8, wherein the filtering means comprises a second bandpass filter having a lower cutoff frequency of 0.4-2 Hz, for example 0.8 Hz, and a higher cutoff frequency of 3-20 Hz, for example 8 Hz.

10. An animal health monitor device according to any preceding claim, wherein the plurality of contact means comprises at least three contact means.11 . An animal health monitor device according to any preceding claim, wherein the plurality of contact means comprises more than four contact means.

12. An animal health monitor device according to any preceding claim, wherein the animal health monitor device further comprises a contact selection means, wherein the contact selection means is configured to determine and / or select a plurality of contact means for applying an alternating current to the skin of the animal and measuring a voltage across the skin of the animal.

13. An animal health monitor device according to claim 10, wherein the contact selection means is configured to determine and / or select an optimal plurality of contact means for applying an alternating current to the skin of the animal and measuring a voltage across the skin of the animal.

14. An animal health monitor device according to claim 11 , wherein the contact selection means is configured to analyse the raw sensor data and / or processed output data for a first plurality and a second plurality of contactmeans, and to determine the optimal plurality of contact means based on the analysis of the raw sensor data and / or processed output data.

15. An animal health monitor device according to any preceding claim, wherein the attachment means comprises a strap.

16. An animal health monitor device according to any preceding claim, wherein the attachment means comprises fastening means, such as hook-and-loop fasteners.

17. An animal health monitor device according to any preceding claim, wherein the animal health monitor device comprises a communication means for sending or reporting the raw sensor data and / or processed output data to one or more further devices.

18. An animal health monitor device for monitoring the health and / or one or more vital signs of an animal, the animal health monitor device comprising: an attachment means for attaching the animal health monitor device to the animal; a sensing means configured to output raw sensor data; and a processing means configured to produce processed output data from the raw sensor data, wherein the processed output data comprises at least one output signal indicative of the health and / or one or more vital signs of the animal.

19. A system for monitoring the health and / or one or more vital signs of an animal, the system comprising: an animal health monitor device according to any one of claims 1 to 18; and one or more further devices in wireless or wired communication with the animal health monitor device, wherein the one or more further devices are configured to receive sensor data and / or processed output data from the animal health monitor device.

20. A system according to claim 17, wherein the animal health monitor device and / or one or more further devices is configured to provide an alarm or notification.21 .A method for processing data, the method comprising: receiving raw sensor data from a sensing means, the sensing means comprising at least a plurality of contact means for applying an alternating current to the skin of an animal and measuring a voltage across the skin of the animal; and producing processed output data from the raw sensor data, wherein the processed output data comprises at least one output signal indicative of the health and / or one or more vital signs of the animal.

22. A method according to claim 21 , wherein producing processed output data from the raw sensor data comprises: filtering the raw sensor data to obtain a first output signal indicative of the respiration of the animal, wherein the first output signal has a frequency of e.g. between 0.1 Hz and 0.6 Hz; and / or filtering the raw sensor data to obtain a second output signal indicative of the heart rate of an animal, wherein the second output signal has a frequency of e.g. between 0.8 Hz and 8 Hz.

23. A method according to claim 21 or claim 22, wherein the sensing means comprises an array of contact means, and wherein the method further comprises: selecting a first plurality of contact means from the array of contact means; applying an alternating current and measuring a voltage using the first plurality of contact means; analysing the raw sensor data output from the first plurality of contact means; and selecting a second plurality of contact means from the array of contact means;applying an alternating current and measuring a voltage using the second plurality of contact means; analysing the raw sensor data output from the second plurality of contact means.

24. A method according to claim 23, wherein the method further comprises: selecting an optimal plurality of contact means based on the analysis of the raw sensor data output from the first plurality of contact means and the second plurality of contact means.

25. A method according to any one of claims 21 to 24, wherein the method further comprises sending or reporting the raw sensor data and / or processed output data to one or more further devices.

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