Device and method for killing at least one small animal using CO2

Abstract

Device (10) for killing at least one small animal, in particular a rodent, by introducing a CO2-containing gas mixture into a cage enclosing the small animal, with a mixing device (14) which - a first gas connection (32) for supplying CO2 gas, - a second gas connection (30) for supplying a further component of the gas mixture, - a mixing chamber (40) connected to these gas connections (30, 32) for mixing the CO2 gas and the further component and - a third gas connection (28) for introducing the CO2-containing gas mixture into the cage, wherein the second gas connection (30) and the third gas connection (28) are designed and / or arranged such that these two gas connections (28, 30) can be fluidically connected to the cage at the same time, and wherein the second gas connection (30) and the third gas connection (28) are arranged such that these two connections (28, 30) enable a fluidic connection to a common cage side of the cage, and wherein the mixing device (14) further comprises a further mixing chamber (42) fluidically connected downstream of the mixing chamber (40) for further mixing the components mixed in the one mixing chamber (40), wherein the third gas connection (28) is fluidically connected downstream of the further mixing chamber (42), and the two mixing chambers (40, 42) are connected to one another via a channel (46),in which a fan (60) or compressor is arranged.,

Description

[0001] The invention relates to a device and a method for killing at least one small animal, in particular a rodent, by introducing a CO2-containing gas mixture into a cage enclosing the small animal.

[0002] The publication US 2012 / 0 272 919 A1 describes a device for killing at least one rodent by introducing CO2 gas or a CO2-containing gas mixture into a cage containing the rodent. The device comprises a line system with a gas connection for introducing the CO2-containing gas mixture into the cage. The corresponding cages, in turn, have (counter) connections through which the animals in the cages can be specifically supplied with a desired gas atmosphere.

[0003] Modern animal protection places very high demands on CO2 killing. In some countries, CO2 (carbon dioxide) may only be used to kill certain small animals, such as mice and rats, which are typical laboratory animals.

[0004] CO2 is a respiratory stimulant and rapidly causes dyspnea, or shortness of breath, in vertebrates. Furthermore, it can cause discomfort and pain because carbon dioxide, in contact with the fluid on the nasal, oral, and ocular mucous membranes, is converted into carbonic acid, which in turn activates polymodal nociceptors. If the animal notices a sharp increase in CO2 concentration, it will attempt to escape, which is impossible in a closed cage and thus causes significant stress. Therefore, CO2 should only be used to kill animals that are already unconscious.

[0005] As early as 1978, US Pat. No. 4,107,818 A described a method for killing cats by introducing a CO2 / O2 gas mixture into a cage containing the small animal. The cat is first exposed for a certain period to a gas mixture with a 40-70% CO2 concentration, which has an anesthetic effect, and then exposed for a certain period to a CO2 / O2 gas mixture with a CO2 concentration of over 95%, which has a lethal effect. Each of the two gas mixtures is kept in a separate chamber, and the cat and its cage are moved first to one chamber and then to the other. However, such a procedure is complex in practice and stressful for the animal.

[0006] The publications US 2007 / 0 026 779 A1 and KR 10 2011 0 032 932 A describe further devices for killing small animals. The publications DE 43 08 585 A1 and WO 2006 / 092 008 A1 describe devices for killing pests.

[0007] The object of the invention is to provide measures for CO2 killing of small animals which ensure that the animal is exposed to as little stress as possible during the entire process and has safely lost consciousness before the actual killing.

[0008] The object is achieved according to the invention by the features of the independent claims. Advantageous embodiments of the invention are specified in the subclaims.

[0009] In the device for killing at least one small animal by introducing a CO2-containing gas mixture into a cage enclosing the small animal, the invention provides that it has a mixing device which in turn has (i) a first gas connection for supplying CO2 gas, (ii) a second gas connection for supplying a further component of the gas mixture, (iii) a mixing chamber connected to these gas connections for mixing the CO2 gas and the further component, and (iv) a third gas connection for introducing the CO2-containing gas mixture into the cage, wherein the second gas connection and the third gas connection are designed and / or arranged such that these two gas connections can be fluidically connected to the cage at the same time, in particular directly to the cage. The second gas connection thus forms a gas connection for introducing atmosphere from the cage as a component of the gas mixture.In other words, this arrangement of the second and third gas connections allows atmosphere from the cage (as a component of the gas mixture) to be introduced into the mixing chamber via the second gas connection for mixing with CO2 gas, while the CO2-containing gas mixture is introduced into the cage via the third gas connection.

[0010] This measure allows the device to be operated in such a way that atmosphere is continuously or quasi-continuously removed from the cage, to which CO2 gas is then successively added. The resulting CO2-containing gas mixture is then reintroduced into the cage at increasingly higher CO2 concentrations. During this circular process, the CO2 concentration in the cage is automatically "ramped up." The rate of concentration increase can then be selected to suit the animal species or animal weight.

[0011] Furthermore, it is provided that the second gas connection and the third gas connection are arranged such that these two connections enable a fluidic connection to a common cage side of the cage. For this purpose, these connections are arranged, for example, next to each other or one above the other at a predefined distance and aligned parallel to each other.

[0012] Each of the two connections is preferably designed as a plug-in contact for direct fluidic connection to a respective socket-like mating contact of the cage. Preferably, each of the connections designed as a plug-in contact has a seal on its outer circumference. This seal is preferably designed as an O-ring.

[0013] The mixing device also has a further mixing chamber downstream of the mixing chamber for further mixing the components mixed in the first mixing chamber. The third gas connection is downstream of the second mixing chamber. This two-stage mixing allows a highly homogeneous CO2-containing gas mixture to be introduced into the cage.

[0014] The two mixing chambers are connected via a duct containing a fan or compressor. Typically, a fan is used rather than a compressor, as the goal is to create a mass flow rather than a pressure difference. The fan is specifically a blower. In addition to driving the mass flow into the other mixing chamber, it also swirls the gas mixture, resulting in faster / additional mixing.

[0015] According to a further preferred embodiment of the invention, the device further comprises a control and / or regulating device. This controls or regulates the said cyclic process. Since the concentration of CO2 gas in the cage is automatically "ramped up" during this cyclic process, closed-loop control can be dispensed with. The control and / or regulating device can therefore be operated purely as a control device. The corresponding control variables are then, for example, the CO2 mass flow, the mass conversion of the fan, and the total process duration. The corresponding fixed variables are then the volumes of the cage and mixing chamber(s).

[0016] In a configuration with two mixing chambers, it is advantageous for the control and / or regulating device to be arranged between the two mixing chambers. This allows it to be particularly close to the components to be controlled / regulated, such as the fan or compressor, or other components such as a switching valve for switching a corresponding CO2 gas source on or off.

[0017] According to a preferred embodiment of the invention, the device has a button or other sensor for registering a defined mounting position of the cage on the device, in which the second gas connection and the third gas connection fluidically contact the cage.

[0018] According to a further preferred embodiment of the invention, the device has a rail system for mounting the cage on the device. Such a rail system is widespread. The initially mentioned document US 2012 / 0 272 919 A1, for example, shows such a rail system with two rails each, on which the cage can be precisely guided to the connection(s) of the corresponding device. In the same way, with the device described here, it is possible to guide a cage with corresponding mating connections / contacts to the second and third gas connections. If said connections (second and third gas connections) are each designed in the form of a plug contact for direct fluidic connection to a respective socket-like mating contact of the cage, their respective longitudinal axes are aligned parallel to the longitudinal axes of the rails.

[0019] Finally, according to yet another preferred embodiment of the invention, the device comprises a base element, in particular a base plate, on which the mixing device is mounted. In a device with a rail system, the rails of the system are preferably also mounted on this base element.

[0020] The method according to the invention for killing at least one small animal by introducing a CO2-containing gas mixture into a cage enclosing the small animal comprises a continuous or quasi-continuous process in which (a) atmosphere is removed from the cage, (b) CO2 gas is added to this removed atmosphere, and (c) the resulting CO2-containing gas mixture is reintroduced into the cage. During this circulating process, the CO2 concentration in the cage is automatically "ramped up." The rate of concentration increase can then be selected to suit the animal species or animal weight.

[0021] The CO2 gas is preferably mixed in two stages. This two-stage mixing process allows a particularly homogeneous CO2-containing gas mixture to be introduced into the cage.

[0022] The above-mentioned embodiments of the device also apply analogously to the relevant embodiments of the method.

[0023] The process is carried out using the device mentioned above.

[0024] The invention will now be explained by way of example with reference to the accompanying drawings using preferred embodiments, wherein the features presented below may represent an aspect of the invention both individually and in combination. It shows: Fig. 1 a device for killing at least one small animal by introducing a CO2-containing gas mixture into a cage enclosing the small animal according to a preferred embodiment of the invention, Fig. 2 the device from a different perspective, Fig. 3 the device with the mixing device open, Fig. 4 the opened mixing device from a different perspective, Fig. 5 the opened mixing device with the interior of a functional module of the mixing device, Fig. 6 of the Fig. 5 shown part of the device from a different perspective, Fig. 7 the mixing device in exploded view and Fig. 8 the gas flow in the mixing device.

[0025] The Fig. 1 shows a device 10 for killing at least one small animal kept in a cage (not shown) using CO2. These small animals are, in particular, rodents such as rats and mice. The device 10 has the following assemblies 12, 14, 16: a base element 12 designed as a base plate, a mixing device 14 for mixing gases, and a rail system 16 with two rails 18, which defines a receiving space 20 for the cage and via which the cage can be brought close to the mixing device 14. The mixing device 14 has a substantially rectangular housing 22. On the front wall 24 of this housing 22 facing the rail system 16, the mixing device 14 has a sensor 26 designed as a button and two gas connections 28, 30. These are matched to corresponding (counter) connections on the cage. The sensor 26 detects the presence of a cage inserted into the receiving space 20.The two connections 28, 30 serve to fluidically connect the mixing device 14 to the cage. The two connections 28, 30 are not the only gas connections of the mixing device 14. On the rear side of the mixing device 14, there is a gas connection, referred to below as the first gas connection 32, for supplying CO2 gas. Fig. 2. The first-mentioned gas connections 28, 30 are referred to below as the second gas connection 30 and the third gas connection 28. The second gas connection 30 serves to supply a further gas component of the CO2-containing gas mixture to be mixed via the mixing device, and the third gas connection 28 serves to introduce this CO2-containing gas mixture into the cage. The further component of the CO2-containing gas mixture is gas or a gas mixture that is extracted from the cage. This gas is the atmosphere surrounding the animal in the cage.

[0026] The Fig. Figure 2 now shows the device 10 from the rear. On a rear wall 34 of the housing 22 opposite the front wall 24, in addition to the aforementioned first gas connection 32, which is designed as a plug-in gas connection piece, an electrical fuse 36 and a socket 38 for supplying power to the device 10 can be seen.

[0027] The rear panel 34 is designed to be removable. Fig. 3 shows the device 10 with the rear wall 34 of the housing 22 of the mixing device 14 removed. The interior of the housing 22 is roughly divided into three areas: a mixing chamber 40, which is also referred to as a return chamber with regard to its function, a further mixing chamber 42, which is also referred to as a feed chamber with regard to its function, and a functional module 44 arranged between the two mixing chambers and separating them, which will be discussed in more detail below.

[0028] The Fig. Figure 4 shows the mixing device 14 with the housing 22 open once again in detail. It can be seen that the functional module 44 is traversed by a channel 46 that fluidically connects the two mixing chambers 40, 42. In other words, this channel 46 extends from one mixing chamber 40 to the other mixing chamber 42.

[0029] In the presentation of the Fig. 4 it can now also be seen that the second gas connection 30 is fluidically connected to the mixing chamber 40, while the third gas connection 28 is connected to the further mixing chamber.

[0030] The Fig. 5 shows, in addition to other components of the device 10, the interior of the module 44. There, the components of a control and / or regulating device 48, which in the example shown is designed as a pure control unit, are located. These are:

[0031] A control module 50 with a time relay, a distribution terminal 52, LEDs 54, and the sensor 26 designed as a button. In addition, the module 44 also houses a solenoid valve 56, a gas throttle valve 58, and a fan 60 designed as a fan, the housing of which (co-)forms the channel 46 and whose rotor is located in the channel 46. An existing CO2 supply line via the first gas connection 32, the solenoid valve 56, and the throttle valve 58 into the mixing chamber 40 is not shown in detail.

[0032] The Fig. 6 shows the Fig. 5 from a slightly different perspective. The control module 50 of the control unit 48 controls the parameters with which the device 10 specifies the gas flow via the sensor 26, which specifies the start time of the process, the solenoid valve 56, which controls the CO2 inflow, and the fan 60, which drives the circulating gas flow.

[0033] The Fig. 7 shows the mixing device 14 with the housing 22 open on the side in a kind of exploded view, in which some of the walls are shown semi-transparent.

[0034] The Fig. 8 shows the device 10 finally in a representation which corresponds to the representation of the Fig. 4, whereby the circulating flow path now leads from the cage via the second gas connection 30 into the mixing chamber 40 (first arrow), from there - driven by the fan 60 - via the channel 46 into the further mixing chamber 42 (second half-hidden arrow) and from there via the third gas connection 28 (third arrow) back into the cage.

[0035] By means of this device 10, small animals kept in cages can now be killed fully automatically by introducing a CO2-containing gas mixture into their cages. For this purpose, in a continuous or quasi-continuous process - 30 atmospheres are removed from the respective cage via the second gas connection, - a CO2 gas introduced via the first gas connection 32 is added to this extracted atmosphere in the mixing chamber 40 and - the resulting CO2-containing gas mixture is fed back into the cage via the third gas connection 28.

[0036] In the example shown, the CO2 gas is added in two stages via the two mixing chambers 40 and 42. This two-stage mixing allows a very homogeneous CO2-containing gas mixture to be introduced into the cage.

[0037] During this circular process, the CO2 concentration in the cage is automatically "ramped up." The rate of concentration increase can then be adjusted to suit the animal species or weight.

[0038] In this process, the CO2 concentration is increased from a starting value, usually less than 1%, to a final value of 70% or more at a rate of 10% to 30% per minute to kill the rodents. The preferred rate is approximately 20% per minute. Reference symbol 10 Device 12 Basic element 14 Mixing device 16 rail system 18 rail 20 recording room 22 Housing (mixing device) 24 front wall 26 Sensor 28 third gas connection 30 second gas connection 32 first gas connection 34 Rear wall 36 Fuse 38 Power supply socket 40 Mixing chamber 42 additional mixing chambers 44 Function module 46 channel 48 Control and / or regulating device 50 control module 52 distribution terminal 54 LED 56 Solenoid valve 58 Gas throttle valve 60 Fan

Claims

[1] Device (10) for killing at least one small animal, in particular a rodent, by introducing a CO2-containing gas mixture into a cage enclosing the small animal, with a mixing device (14) which - a first gas connection (32) for supplying CO2 gas, - a second gas connection (30) for supplying a further component of the gas mixture, - a mixing chamber (40) connected to these gas connections (30, 32) for mixing the CO2 gas and the further component and - a third gas connection (28) for introducing the CO2-containing gas mixture into the cage, wherein the second gas connection (30) and the third gas connection (28) are designed and / or arranged such that these two gas connections (28, 30) can be fluidically connected to the cage at the same time, and wherein the second gas connection (30) and the third gas connection (28) are arranged such that these two connections (28, 30) enable a fluidic connection to a common cage side of the cage, and wherein the mixing device (14) further comprises a further mixing chamber (42) fluidically connected downstream of the mixing chamber (40) for further mixing the components mixed in the one mixing chamber (40), wherein the third gas connection (28) is fluidically connected downstream of the further mixing chamber (42), and the two mixing chambers (40, 42) are connected to one another via a channel (46),in which a fan (60) or compressor is arranged., [2] Device according to claim 1, characterized by that each of the two connections (28, 30) is preferably designed in the form of a plug contact for direct fluidic connection to a respective socket-like counter-contact of the cage. [3] Device according to claim 1 or 2, characterized by a control and / or regulating device (48). [4] Device according to claim 3, characterized by that the control and / or regulating device (48) is arranged between the two mixing chambers (40, 42). [5] Device according to one of the preceding claims, characterized by a button or other sensor (26) for registering a defined mounting position of the cage on the device (10), in which the second gas connection (30) and the third gas connection (28) are in fluid contact with the cage. [6] Device according to one of the preceding claims, characterized bya rail system (16) for mounting the cage to the device (10). [7] Device according to one of the preceding claims, characterized by a base element (12), in particular a base plate, on which the mixing device (14) is fastened. [8] Method for killing at least one small animal, in particular a rodent, by means of the device according to one of claims 1 to 7 by introducing a CO2-containing gas mixture into a cage enclosing the small animal, wherein in a continuous or quasi-continuous process - the cage is deprived of atmosphere, - CO2 gas is added to this extracted atmosphere and - the resulting CO2-containing gas mixture is fed back into the cage.

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