A device for assisting in ear marginal vein injection of a domestic rabbit

Abstract

The present application relates to experimental animal auxiliary equipment technical field, especially to a kind of domestic rabbit ear edge intravenous injection auxiliary device, including transparent bottom plate assembly, fixed component, temperature control development component and blood return visualization feedback component;The transparent bottom plate assembly includes transparent bottom plate and frame, the frame inside groove contains the outer edge of transparent bottom plate and the upper edge of frame is higher than the top surface of transparent bottom plate;The temperature control development component includes slot, replaceable heating element and the heat insulation layer between heating element and transparent bottom plate, to make ear edge vein dilatation development in passive heating mode;The blood return visualization feedback component includes transparent joint between injection needle and injector, and the fluid passage in transparent joint is partially expanded in middle part to form blood return observation area, visual signal of needle tip into blood vessel is immediately presented, the present device improves the puncture success rate of domestic rabbit ear edge intravenous injection.

Description

Technical Field

[0001] This invention relates to the field of laboratory animal auxiliary equipment technology, and particularly to an auxiliary device for improving the clarity of vascular visualization and ease of operation during marginal ear vein injection in rabbits. This invention is especially applicable to scenarios involving marginal ear vein drug administration or blood collection in rabbits during pharmacological, toxicological, immunological, and preclinical evaluation processes. Background Technology

[0002] Marginal ear vein injection is a common method of drug administration or blood collection in laboratory rabbits. Among the blood vessels in the rabbit ear, the marginal ear veins, running along the outer edge of the ear, are superficial and easy to locate, making them the preferred venous puncture approach for operators. However, due to the small diameter, thin walls, and complex distribution along the auricle, the marginal ear veins are prone to active contraction in low-temperature environments or when the rabbit is stressed or struggling. This narrows the vessel lumen, resulting in unclear vascular visualization. Operators often find it difficult to accurately determine whether the needle has pierced the blood vessel, leading to multiple punctures, local swelling and bleeding in the rabbit's ear, injury to the laboratory animal, and errors in experimental data.

[0003] Several auxiliary solutions have been proposed in the existing technology for the process of injecting blood into the marginal ear vein of rabbits. The first type of solution is to use a special rabbit restraint operating table to physically restrain the rabbit. For example, the existing technology discloses a rabbit marginal ear vein injection operating table, including a rabbit box, a middle partition, a base plate, and an injection table. The rabbit box includes a top cover and a body. The rabbit box body has a through hole on one side to allow the rabbit's ear to protrude. The middle partition has multiple holes to allow the rabbit's legs to extend into the lower space, thereby eliminating the rabbit's fulcrum. The injection table has a groove and elastic clips to hold the rabbit's ear. The core purpose of this solution is to prevent the rabbit from struggling and jumping out of the rabbit box during the injection process. However, this solution does not address the problem of unclear blood vessel visualization, nor does it provide any immediate feedback on whether the injection needle has successfully entered the blood vessel. The operator still needs to rely on experience and touch to judge the needle position, and there is still a high failure rate for punctures in rabbits with small blood vessels or in a tense state.

[0004] The second type of solution uses a heating element to locally heat the injection site. For example, existing technology discloses an intravenous injection vascular relaxation protection device, including a bandage, a first Velcro strap, a second Velcro strap, a heating pack, a soft glass, a tilted cover, a heat insulation cloth, and a recess. The heating pack is filled with reduced iron powder. After opening the membrane at the top of the heating pack, air enters the heating pack through the air inlet. The reduced iron powder reacts with the air, undergoing an oxidation reaction and releasing chemical heat. The soft glass is located in the middle of the heating pack. Medical personnel can observe the position of the indwelling needle by lifting the tilted cover to expose the soft glass. In this solution, the heat source is the chemical exothermic reaction of iron powder, and the output temperature cannot be precisely controlled or maintained stably for a long time. The soft glass in the device only serves to observe the position of the indwelling needle, not to assist in vascular imaging. Furthermore, the heating pack, soft glass, heat insulation cloth, and other components in this solution are stacked as a whole, and the heating pack is not replaceable. Furthermore, this procedure is designed for intravenous injection in the arm of an adult human, not for the ear structure of a rabbit, and therefore cannot be adapted to the temperature window and support surface required for intravenous injection in the ear margin of a rabbit.

[0005] The third approach involves actively imaging blood vessels using illumination or optical imaging. For example, existing technology discloses an infrared transmission 3D angiography device, including a main control board, a light source module, lenses, and infrared 3D glasses. The light source module contains two-way light-emitting diodes (LEDs) with an emission wavelength of 685nm. The infrared 3D glasses' lenses include liquid crystal light valves and filters. The main control board illuminates light source 1 and light source 2 according to a set timing sequence, thereby forming a three-dimensional blood vessel image in the liquid crystal light valves of the left and right eyes of the infrared 3D glasses. This approach achieves blood vessel imaging through active infrared light transmission and time-division stereoscopic imaging. However, it is structurally complex, large in size, and relies on electronic components and battery power. For thin tissues less than 2mm thick, such as the marginal ear vein of rabbits used in laboratory animals, the structural and costly overhead is too high. Furthermore, this approach does not solve the problem of real-time feedback on whether the injection needle has successfully entered the blood vessel; blood vessel imaging and needle position feedback remain two separate operational steps.

[0006] In summary, the existing technology has the following three specific technical problems that need to be solved. First, for small blood vessels such as the rabbit ear vein, which are located in thin, translucent tissue, existing imaging methods either rely on complex optical imaging equipment or uncontrollable chemical exothermic heating methods, lacking a simple and temperature-controllable auxiliary scheme for vascular imaging using passive local temperature regulation. Second, existing devices either have heating elements that are disconnected from the supporting base, or the heating elements are not replaceable, or there is a risk of burns from direct contact between the heating elements and the skin, lacking a device structure that integrates support, heating, insulation, and safety edges. Third, existing solutions rely solely on the operator's tactile judgment or post-operative observation of drug extravasation to determine whether the needle has successfully entered the blood vessel, lacking a structured, real-time feedback channel that directly generates a visual blood return signal between the injection needle and syringe. Summary of the Invention

[0007] The purpose of this invention is to address the problems of the prior art described in the background section by providing a rabbit ear vein injection auxiliary device. This device promotes ear vein dilation through passive local temperature regulation, thereby improving the clarity of vascular visualization. It provides an operating base surface that balances safety margins with a transparent base plate structure that integrates support and observation. It provides a temperature control mode that is both temperature-controlled and easy to replace with a layered structure of replaceable heating elements and insulation layers. Furthermore, it provides the operator with an independent blood return visualization feedback component that provides an immediate visual signal indicating whether the needle has successfully entered the blood vessel.

[0008] To achieve the above objectives, the technical solution provided by the present invention is as follows.

[0009] This invention provides an auxiliary device for rabbit marginal ear vein injection, comprising a transparent base plate assembly, a fixation assembly, a temperature-controlled imaging assembly, and a blood return visualization feedback assembly. The transparent base plate assembly includes a transparent base plate and a frame. The transparent base plate is made of a light-transmitting material. The frame is disposed along the outer edge of the transparent base plate, and an annular groove is provided on the inner side of the frame. The outer edge of the transparent base plate is embedded in the groove. The top surface of the transparent base plate is lower than the upper edge of the frame, and the upper inner edge of the frame has a rounded transition portion. The fixation assembly includes a distal fixator and a proximal fixator, which are respectively disposed on both sides of the transparent base plate assembly. The distal and proximal fixators are used to fix the distal and proximal ends of the rabbit's ear, respectively. The temperature-controlled imaging component includes a slot, a replaceable heating element, and a heat insulation layer. The slot is located below the transparent base plate. The replaceable heating element is detachably inserted into the slot. The heat insulation layer is located between the transparent base plate and the replaceable heating element. The replaceable heating element locally heats the transparent base plate through the heat insulation layer, causing the marginal ear veins of the rabbit to dilate and become visible. The blood return visualization feedback component includes a transparent connector located between the injection needle and the syringe. One end of the transparent connector has a first interface, and the other end has a second interface. The first interface is connected to the injection needle, and the second interface is connected to the syringe. A fluid channel is formed inside the transparent connector, connecting the first interface and the second interface. The fluid channel is locally expanded in the middle of the transparent connector to form a blood return observation area.

[0010] In a preferred embodiment of the present invention, the groove is a stepped support groove with the opening facing upward. The groove includes a horizontal support surface that supports the outer edge of the transparent base plate and a vertical inner wall that abuts against the side of the outer edge of the transparent base plate. The portion of the vertical inner wall that extends above the top surface of the transparent base plate together with the top surface of the transparent base plate forms a locking position. The locking position is used to accommodate and limit the edge of the rabbit's ear.

[0011] In a preferred embodiment of the present invention, the heat insulation layer is a silicone heat insulation layer, and the thickness of the silicone heat insulation layer is 1mm to 2mm.

[0012] In a preferred embodiment of the present invention, the inner wall of the slot is provided with an anti-slip structure, which is an array of micro-protrusions or an array of grooves that contacts the back of the replaceable heating element. The array of micro-protrusions consists of multiple protrusions arranged along the inner wall of the slot, and the array of grooves consists of multiple recesses arranged along the inner wall of the slot.

[0013] In a preferred embodiment of the present invention, the replaceable heating element heats the transparent base plate through the silicone heat insulation layer, so that the top surface of the transparent base plate forms a local heating temperature of 38°C to 42°C.

[0014] In a preferred embodiment of the present invention, the distal end fixing member and the proximal end fixing member are spaced apart from each other along the length direction of the transparent base plate assembly, and the distal end fixing member and the proximal end fixing member are independently adjustable.

[0015] In a preferred embodiment of the present invention, the volume of the blood return observation area is configured to make the instantaneous blood return visible after the injection needle enters the blood vessel, and the volume of the blood return observation area does not change the injection dosage accuracy between the injection needle and the syringe.

[0016] In a preferred embodiment of the present invention, the blood return observation area extends along the axial direction of the fluid channel, and the blood return observation area is symmetrically arranged between the first interface and the second interface along the axial direction.

[0017] In a preferred embodiment of the present invention, the replaceable heating element is a constant temperature heating pad, and the working surface temperature of the constant temperature heating pad is constant within a set range.

[0018] In a preferred embodiment of the present invention, the transparent base plate is made of one of acrylic resin, polycarbonate or borosilicate glass.

[0019] Compared with the prior art, the present invention has the following beneficial effects.

[0020] First, this invention integrates the supporting surface of the rabbit ear with the vascular observation plane through the cooperation of the transparent base plate and the frame of the transparent base plate assembly. The rabbit auricle itself is a natural translucent thin layer of tissue with a thickness between 1mm and 2mm. When the rabbit ear is laid flat on the transparent base plate, the light-transmitting property of the transparent base plate allows the operator to observe the projection position of the marginal ear vein on the surface of the base plate from below or to the side. The frame is set along the outer edge of the transparent base plate. The annular groove on the inner side of the frame accommodates the outer edge of the transparent base plate, so that the top surface of the transparent base plate is lower than the upper edge of the frame. The inner wall of the frame, which is higher than the top surface of the transparent base plate, together with the top surface of the transparent base plate, forms a shallow support for supporting the edge of the rabbit's ear. The upper inner edge of the frame is provided with a rounded transition part. The edge of the rabbit's ear rests on the rounded transition part without contacting the sharp edge. There is no local shear stress concentration area between the edge of the rabbit's ear and the frame due to the step edge. The pain stimulation and struggling tendency of the rabbit during the operation are significantly reduced.

[0021] Secondly, this invention achieves passive regulation and safety constraint of the temperature on the top surface of the transparent substrate through a three-layer superimposed structure of the replaceable heating element, the heat insulation layer, and the slot in the temperature-controlled developing assembly. The heat insulation layer is positioned between the replaceable heating element and the transparent substrate. This layer neither completely blocks heat transfer nor prevents the heat from the heating element from directly reaching the substrate surface. Instead, it diffuses and evenly distributes the uneven heat spots of the heating element in space before slowly transferring them to the transparent substrate, creating a uniformly heated surface on the top of the transparent substrate. The replaceable heating element is detachably inserted into the slot, allowing the operator to replace it according to different batches and specifications, making the device both versatile and durable.

[0022] Third, this invention sets the local heating temperature of the top surface of the transparent base plate within a window range of 38°C to 42°C. This ensures that the heating process induces a thermal response dilation of the smooth muscle in the marginal ear veins without exceeding the burn threshold of the rabbit's ear skin. A rabbit's normal body temperature is between 38.5°C and 39.5°C, and the skin temperature of a rabbit's ear is typically lower than its trunk temperature. The burn threshold for rabbit skin is generally not lower than 44°C, and there is a requirement for sustained application time. Therefore, a top surface heating temperature of 38°C to 42°C falls precisely within the effective range of vasodilation response while also providing a safety margin of over 2°C. The local heating temperature is achieved through the coordinated use of the thickness of the insulation layer, the temperature parameters of the replaceable heating element, and the thermal conductivity of the transparent base plate material, resulting in strong parameter coordination and high robustness.

[0023] Fourth, the present invention limits the relative displacement of the replaceable heating element within the slot through an anti-slip structure on the inner wall of the slot. Slight movement of the rabbit during injection, the operator's hand movements during assembly of the heating element, and the softening of the back of the heating element as the temperature rises can all cause the heating element to shift within the slot. The anti-slip structure uses a micro-protrusion array or groove array to form a geometric fit with the surface of the heating element. This fit becomes even tighter as the temperature of the heating element rises due to the slight softening of the back of the heating element, thereby spatially fixing the position of the heating element and maintaining spatial consistency of the heating temperature on the top surface of the transparent base plate.

[0024] Fifth, this invention utilizes the independent arrangement of the distal and proximal ends of the fixing components to create a redundant, double-tensioned constraint on the rabbit's ear. During the heating and imaging process, the rabbit's ear thickens locally due to vasodilation. A single clamping point or a single-sided elastic clip cannot effectively counteract the asymmetrical changes in axial tension of the ear. The distal and proximal fixing components are spaced apart along the length of the transparent base plate assembly and can be independently adjusted. This allows the operator to fine-tune the tension at both ends according to the length of the rabbit's ear and the degree of vasodilation, effectively eliminating ear twisting and slippage caused by single-point clamping.

[0025] Sixth, this invention constructs an independent early warning window between the injection needle and syringe through the transparent connector of the blood return visualization feedback component and the blood return observation area located in the middle of the transparent connector. The intravascular blood pressure at the moment the injection needle pierces the blood vessel forms a microsecond-level pressure difference pulse, and the blood instantly flows back to the blood return observation area along the first interface. The local expansion geometry of the blood return observation area causes the trace amount of backflowing blood to generate a visible red signal within this area. The operator can immediately determine the needle position without waiting for tactile feedback or subsequent extravasation observation, significantly improving the timeliness of puncture success assessment. Simultaneously, the volume of the blood return observation area is designed to be a trace value sufficient to form a visual signal without affecting the accuracy of the injection dosage. The axially symmetrical layout of the blood return observation area allows the operator to observe changes in blood return from either the left or right side.

[0026] Seventh, this invention constructs a complete closed-loop operation from support, heating, imaging, fixation, and feedback through multi-channel parallel collaboration among the transparent base plate assembly, the temperature-controlled imaging assembly, and the blood return visualization feedback assembly. After the rabbit's ear is placed on the top surface of the transparent base plate assembly, the temperature-controlled imaging assembly continuously heats the area locally to dilate the marginal ear veins. The light transmittance of the transparent base plate allows the operator to clearly observe the position of the blood vessel projection. The fixation assembly maintains the stability of the rabbit's ear during heating and injection. The blood return signal at the moment the injection needle pierces the blood vessel is visually amplified by the blood return visualization feedback assembly. The entire operation process does not rely on any active electronic devices or complex optical imaging systems. The device has a simple structure, low cost, and flexible assembly. Each functional component can be disassembled or replaced as needed, achieving multiple auxiliary functions without significantly increasing the complexity of operation. Attached Figure Description

[0027] Figure 1 This is a top view of the overall assembly of the rabbit ear vein injection auxiliary device described in this invention.

[0028] Figure 2This is a longitudinal sectional view from the front view of the rabbit ear vein injection auxiliary device described in this invention, showing the stacked structure of the transparent base plate assembly and the temperature-controlled imaging assembly.

[0029] Figure 3 This is a partially enlarged cross-sectional view of the temperature-controlled developing assembly described in this invention, showing the assembly relationship of the anti-slip structure on the inner wall of the slot, the replaceable heating element, and the heat insulation layer.

[0030] Figure 4 This is a schematic diagram of the dual-end layout of the distal end fixation member and the proximal end fixation member of the fixing component described in this invention. The position of the rabbit's ear is indicated by a dashed line.

[0031] Figure 5 This is a longitudinal sectional view of the blood return visualization feedback component described in this invention, showing the axially symmetrical structure of the transparent connector, the first interface, the second interface, the fluid channel, and the blood return observation area.

[0032] Figure 6 This is a schematic diagram of the implementation state of the rabbit ear vein injection auxiliary device according to the present invention, showing the operation process of temperature-controlled imaging and blood return observation after the rabbit ear is inserted into the groove.

[0033] In the diagram, 1 is the transparent base plate assembly, 2 is the transparent base plate, 3 is the frame, 4 is the groove, 5 is the fixing assembly, 51 is the distal end fixing component, 52 is the proximal end fixing component, 6 is the temperature-controlled imaging assembly, 61 is the slot, 62 is the replaceable heating element, 63 is the heat insulation layer, 64 is the anti-slip structure, 7 is the blood return visualization feedback assembly, 71 is the transparent connector, 72 is the first interface, 73 is the second interface, 74 is the fluid channel, and 75 is the blood return observation area. Detailed Implementation

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] It should be noted that the orientation descriptions used in this specification, such as up, down, left, right, inner, outer, proximal end, and distal end, are only used to illustrate the relative positional relationship of each component in the embodiment shown in the accompanying drawings, and do not constitute a limitation on the structure of the present invention.

[0036] Example 1

[0037] See Figure 1 and Figure 2This embodiment provides a rabbit ear vein injection auxiliary device, including a transparent base plate assembly 1, a fixing assembly 5, a temperature control imaging assembly 6, and a blood return visualization feedback assembly 7. The structure and assembly relationship of each component are described in detail below.

[0038] The transparent base plate assembly 1 includes a transparent base plate 2 and a frame 3. The transparent base plate 2 is made of acrylic resin sheet with a light transmittance of not less than 90%. In this embodiment, the transparent base plate 2 is a rectangular flat plate with a length of 180mm, a width of 90mm, and a thickness of 4mm. The length and width dimensions used in this embodiment match the unfolded size of the ear flaps of common laboratory rabbits such as New Zealand White Rabbits and Blue Rabbits. The 4mm thickness balances light transmittance, structural rigidity, and processing feasibility. In other embodiments, the transparent base plate 2 can also be made of polycarbonate sheet or borosilicate glass sheet. All three materials have good visible light transmittance, can withstand local heating below 80°C without significant deformation, and meet the safety requirements for use in contact with laboratory animals.

[0039] The frame 3 is arranged around the outer edge of the transparent base plate 2. The frame 3 is made of 6063 series aluminum alloy profile. The inner side of the frame 3 is provided with an upward-facing stepped groove 4. The groove 4 includes a horizontal support surface and a vertical inner wall located on the outer side of the outer edge of the transparent base plate 2. The horizontal support surface is used to support the outer edge of the transparent base plate 2, and the vertical inner wall extends upward along the side of the outer edge of the transparent base plate 2 and is higher than the top surface of the transparent base plate 2. The assembly gap between the horizontal support surface of the groove 4 and the lower surface of the outer edge of the transparent base plate 2 is 0.1mm to 0.2mm. During assembly, the outer edge of the transparent base plate 2 is placed on the horizontal support surface of the groove 4, so that the side of the outer edge of the transparent base plate 2 abuts against the vertical inner wall of the groove 4. The upper edge of the frame 3 is higher than the top surface of the transparent base plate 2, and the height of the upper edge of the frame 3 above the top surface of the transparent base plate 2 is 0.5mm to 2mm. In this embodiment, the height is 1mm. The vertical inner wall of the frame 3 above the top surface of the transparent base plate 2 and the top surface of the transparent base plate 2 together form a shallow locking position for supporting the edge of the rabbit's ear. When the height of the upper edge of the frame 3 above the top surface of the transparent base plate 2 is less than 0.5 mm, the depth of the shallow locking position is insufficient to form an effective lateral restraint on the edge of the rabbit's ear. When the height is greater than 2 mm, the upper edge of the frame 3 is too high relative to the top surface of the transparent base plate 2, which reduces the convenience of inserting and removing the rabbit's ear. The preferred height is 1 mm. Under this preferred value, the shallow locking position can form a reliable lateral restraint on the edge of the rabbit's ear without hindering the rapid insertion and removal of the rabbit's ear. The inner upper edge of frame 3 is provided with a rounded transition section. The radius of the rounded transition section is 0.3mm to 1.5mm, and in this embodiment, the radius is 0.8mm. When the radius is less than 0.3mm, the edge of the rabbit's ear may still contact the transition surface, which is close to a sharp edge. When the radius is greater than 1.5mm, the effective support surface of the inner upper edge of frame 3 that can support the ear is reduced. The radius is preferably 0.8mm, so that the edge of the rabbit's ear rests on the rounded transition section without contacting the sharp edge, thus avoiding local shear stress concentration between the edge of the rabbit's ear and frame 3 due to edge contact. The outer surface of frame 3 can be anodized according to the overall aesthetic design of the device.

[0040] The assembly relationship of the transparent base plate assembly 1 has the following unexpected technical effects. The transparent base plate 2 and the frame 3 form an interlocking fit through the groove 4. When the rabbit's ear is placed into the top surface of the transparent base plate 2 and is tensioned at both ends by the fixing component 5, the edge of the rabbit's ear naturally falls into the shallow locking position formed by the vertical inner wall of the frame 3 that is higher than the top surface of the transparent base plate 2 and the top surface of the transparent base plate 2. The edge of the rabbit's ear is laterally limited by the vertical inner wall. Under the tensioning action of the fixing component 5 at both ends, the edge of the rabbit's ear abuts against the vertical inner wall and does not slip laterally. The operator can achieve secondary stability of the ear along the length direction without setting up a special clamp for the ear edge, thus reducing the total number of parts in the device.

[0041] Furthermore, the structural design of the transparent base plate assembly 1 takes into account the impact of thickness changes and blood flow changes in the rabbit's ear during heating on the stability of the device. The average thickness of the rabbit's auricle in the resting state is approximately 1 mm to 2 mm. When the temperature control imaging assembly 6 raises the temperature of the top surface of the transparent base plate 2 to the range of 38°C to 42°C, the diameter of the rabbit's marginal ear veins expands by approximately 30% to 50%. During the vascular expansion process, the local thickness of the rabbit's ear can increase to 1.2 to 1.5 times that in the resting state. The rounded transition design of the upper inner edge of the frame 3 ensures that even if the edge of the rabbit's auricle comes into contact with the vertical inner wall of the frame 3 during the thickness change process, it only contacts the rounded transition and does not compress against the sharp edges. The increase in ear thickness only causes the height of the auricle relative to the top surface of the transparent base plate 2 to rise, without causing compression damage to the edge of the auricle.

[0042] The light transmittance of the transparent base plate 2 was also carefully considered. In this embodiment, the acrylic resin board used has a visible light transmittance of no less than 90%. This transmittance ensures that the operator can clearly observe the projection position of the rabbit's ear vein through the base plate, while also minimizing visible reflection interference when the operator observes from above. For scenarios requiring higher transmittance, optical-grade polycarbonate boards with a transmittance of no less than 92% or high borosilicate glass boards with a transmittance close to 93% can be used. The surface finish of the transparent base plate 2 reaches Ra0.2 or less, avoiding interference from diffuse reflection caused by microscopic surface roughness on vascular imaging observation. The frame 3 uses anodized aluminum alloy profiles, which have good surface wear resistance and chemical corrosion resistance, suitable for the cleaning needs of frequent contact with disinfectants in experimental environments. The presence of the anodized layer also avoids visual contrast interference between the original color of the aluminum alloy and the rabbit's ear skin.

[0043] The fixing component 5 includes a distal fixing member 51 and a proximal fixing member 52. The distal fixing member 51 and the proximal fixing member 52 are respectively disposed at both ends of the transparent base plate assembly 1 along the length of the ear. The distal fixing member 51 is located near the rabbit's ear tip, and the proximal fixing member 52 is located near the rabbit's ear root. In this embodiment, both the distal fixing member 51 and the proximal fixing member 52 are made of soft silicone elastic clips. The clamping surface of the elastic clips is covered with a low-friction, high-resistance silicone pattern. An adjustable sliding seat is connected to the outer side of the elastic clip. The sliding seat can slide along the length of the transparent base plate assembly 1 and be locked by a knob. This independently adjustable structure allows the position and clamping force of the distal fixing member 51 and the proximal fixing member 52 to be adjusted separately.

[0044] The dual-end arrangement of the fixation component 5 produced an unexpected synergistic effect. During injection, the ear veins in the rabbit ear dilate due to the local heating effect of the temperature-controlled imaging component 6, causing dynamic changes in the local thickness and tension distribution of the rabbit ear. A single clamping point or a unilateral fixation method is insufficient to simultaneously counteract the asymmetrical changes in the axial tension of the ear. The distal fixation component 51 and the proximal fixation component 52 are independently arranged along the length of the transparent base plate component 1 and can be adjusted separately, forming a dual-end tensioned redundant constraint on the rabbit ear. The elastic pre-tightening force generated by this over-constraint positioning eliminates the relative sliding gap between the ear and the transparent base plate 2, ensuring repeatable positioning accuracy of the relative position of the ear veins and the injection needle on the rabbit ear.

[0045] See Figure 2 and Figure 3 The temperature-controlled imaging assembly 6 includes a slot 61, a replaceable heating element 62, and a heat insulation layer 63. The slot 61 is fixedly disposed below the transparent base plate 2, and the slot 61 and the transparent base plate 2 are not in direct contact; a heat insulation layer 63 is provided between them. The heat insulation layer 63 is made of medical-grade silicone sheet, which is bonded to the lower surface of the transparent base plate 2 with silicone adhesive. The lower surface of the silicone sheet is freely exposed above the slot 61 and maintains surface contact with the upper surface of the replaceable heating element 62.

[0046] The size of slot 61 matches the external dimensions of the replaceable heating element 62. In this embodiment, the replaceable heating element 62 is a constant-temperature disposable self-heating heating pad. The heating pad has a length of 90mm, a width of 60mm, and a thickness of 3mm. The self-heating temperature of the heating pad is set to 43℃ and can be maintained for 8 hours. After peeling off the back sealing film, the heating pad is pushed into slot 61 along the opening. The gap between the heating pad and the inner wall of slot 61 is 0.3mm to 0.5mm, allowing sufficient assembly stroke. When a single experiment is completed or the heating pad has reached the recommended usage time, the operator can remove the heating pad from slot 61 and replace it with a new heating pad.

[0047] The inner wall of the slot 61 is provided with an anti-slip structure 64. In this embodiment, the anti-slip structure 64 is an array of micro-protrusions evenly distributed on the bottom surface of the inner wall of the slot 61. The micro-protrusions are hemispherical in shape, with a diameter of 0.5 mm and a center distance of 3 mm between adjacent micro-protrusions. The micro-protrusion array is evenly distributed along the length and width directions of the slot 61. In other embodiments, the anti-slip structure 64 can also be a shallow groove array, a stripe array, or a frosted surface. The anti-slip structure 64 forms a geometric fit and friction enhancement with the back of the replaceable heating element 62. When the operating temperature of the heating element rises, the self-adhesive layer on the back of the heating element softens slightly. The softened self-adhesive layer enters the gaps between the micro-protrusion array to form a filling fit. This fit becomes tighter as the heating process proceeds.

[0048] Regarding the thickness of the insulation layer 63, in this embodiment, the thickness of the silicone insulation layer 63 is 1.5 mm. The thermal conductivity of silicone material is between 0.15 W and 0.25 W per meter Kelvin. This moderate thermal conductivity ensures that the silicone layer neither completely blocks heat transfer like an air layer nor conducts heat almost instantaneously like a metal layer, but rather allows heat to be transferred to the transparent base plate 2 with a controllable time constant. When the thickness of the silicone insulation layer 63 is less than 1 mm, the insulation layer's ability to diffuse hot spots on the surface of the heating element 62 is insufficient, and localized hot spots are prone to appear on the top surface of the transparent base plate 2. When the thickness of the silicone insulation layer 63 is greater than 2 mm, the attenuation of heat transfer by the insulation layer is too large, and the replaceable heating element 62 needs to be set to a higher self-heating temperature to make the top surface of the transparent base plate 2 reach the target temperature range, while the temperature response time is significantly prolonged. The thickness of the silicone insulation layer 63 is set in the range of 1mm to 2mm, with a preferred value of 1.5mm. Under this preferred value, the heating response time of the top surface of the transparent base plate 2 is 3 minutes to 5 minutes, and the temperature spatial non-uniformity of the top surface does not exceed ±0.5℃. This can achieve effective spatial averaging of the hot spots on the surface of the heating element 62, and also ensure sufficient temperature transfer efficiency.

[0049] Regarding the selection of the top surface heating temperature window for the temperature-controlled developing component 6, in this embodiment, the top surface heating temperature range of the transparent base plate 2 is 38°C to 42°C. The normal body temperature range of rabbits is 38.5°C to 39.5°C. Due to heat dissipation from the ears, the skin temperature of rabbit ears is typically 2°C to 4°C lower than the body temperature. In a relaxed state, the surface temperature of a rabbit's ear is approximately 35°C to 37°C. The burn threshold for rabbit ear skin, based on the time-temperature tolerance relationship of skin thermal injury, is typically no less than 44°C and requires sustained application for several seconds before irreversible tissue damage occurs. Therefore, setting the lower limit of the top surface heating temperature of the transparent base plate 2 to 38°C allows the rabbit ear skin temperature to rise from the resting state of 35°C to 37°C to approximately the rabbit's body temperature, thereby activating the thermal response of the smooth muscle in the ear veins and causing vasodilation. Setting the upper limit of the top surface heating temperature of the transparent base plate 2 to 42°C provides a safety margin of more than 2°C between the rabbit ear skin surface temperature and the burn threshold. When the temperature of the top surface of the transparent base plate 2 is below 38℃, the dilation of the ear veins is not obvious, and the improvement in vascular visualization is limited. When the temperature of the top surface of the transparent base plate 2 is above 42℃, local skin redness or even mild burns may occur in the rabbit's ear. At the same time, the skin blood vessels may experience feedback contraction at high temperatures, which may lead to poor vascular visualization. The optimal temperature is 40℃. At this optimal temperature, the diameter of the ear veins dilates by approximately 30% to 50% compared to the resting state, and the clarity of vascular visualization is significantly improved, without any burns or obvious discomfort in the rabbit's ear.

[0050] The heat transfer of the temperature-controlled developing assembly 6 exhibits a clear temporal characteristic. The replaceable heating element 62 begins to heat up the instant it is inserted into the slot 61. In the initial stage of heating, the surface temperature of the heating pad gradually rises to the set temperature of 43°C, a process that lasts approximately 1 to 2 minutes. Heat is transferred from the upper surface of the heating pad to the lower surface of the insulation layer 63. Since the insulation layer 63 is made of silicone, its thermal diffusivity is approximately 0.1 mm² / s. The heat transfer time constant of the 1.5 mm thick silicone layer is approximately 30 to 60 seconds. This time constant allows the insulation layer 63 to significantly average the temperature unevenness on the surface of the heating pad. After passing through the insulation layer 63, the heat continues to be transferred upwards to the lower surface of the transparent base plate 2. Since the transparent base plate 2 is made of acrylic resin, its thermal conductivity is approximately 0.18 W / m Kelvin. The heat transfer time constant of the 4 mm thick transparent base plate 2 is similar to that of the silicone insulation layer 63. The effective time constant of the entire heat transfer chain is calculated to be approximately 2 to 3 minutes. After the replaceable heating element 62 is inserted into the slot 61, the top surface of the transparent base plate 2 reaches a steady-state temperature of 38°C to 42°C within approximately 3 to 5 minutes. This temperature establishment process with a controllable response time avoids the stress response caused by a sudden increase in local temperature in the rabbit's ear, while also providing the operator with ample preparation time.

[0051] The long-term stability of the temperature-controlled imaging component 6 has also been verified. The self-heating temperature of the replaceable heating element 62 can be maintained within the range of 43℃±1℃ during an 8-hour working period, and the steady-state temperature of the top surface of the transparent base plate 2 is correspondingly maintained within the window of 38℃ to 42℃. This stability ensures the continuous observability of vascular imaging during the duration of a single experiment. When the usage time of the replaceable heating element 62 approaches the recommended upper limit or when a single experiment is completed, the operator can remove the heating element from the slot 61 by gently pulling the pre-installed lifting tab and replace it with a new heating element. The side wall of the slot 61 opening has a 20mm wide recess to facilitate the operator's fingers to enter the slot and grasp the heating element. The presence of the anti-slip structure 64 keeps the heating element in a stable spatial position during operation. During removal, the self-adhesive layer on the back of the heating patch has softened with the working temperature, making it relatively easy to remove from the slot. This structural design, which is stable during operation and convenient to remove, reflects the dynamic balance between the anti-slip structure 64 and the temperature response of the heating element.

[0052] See Figure 5 The blood return visualization feedback component 7 includes a transparent connector 71, which is a hollow transparent tubular structure. The two ends of the transparent connector 71 are respectively provided with a first interface 72 and a second interface 73. Both the first interface 72 and the second interface 73 adopt a standard Luer connector structure. The first interface 72 is a Luer female connector used to connect with the Luer male connector of the injection needle, and the second interface 73 is a Luer male connector used to connect with the Luer female connector of the syringe. The combined structure after connection is a series injection flow path of injection needle—first interface 72—transparent connector 71—second interface 73—syringe.

[0053] The transparent connector 71 is made of medical-grade polycarbonate or acrylic resin. The main body of the transparent connector 71 has an outer diameter of 10mm, an inner diameter of 2mm, and a length of 30mm. A fluid channel 74 is formed inside the transparent connector 71, connecting the first interface 72 and the second interface 73. The fluid channel 74 is partially expanded in the middle of the transparent connector 71 to form a blood return observation area 75. The blood return observation area 75 extends axially along the fluid channel 74, has a length of 10mm, and its lateral dimension is 2 to 3 times the inner diameter of the fluid channel 74. The blood return observation area 75 is symmetrically arranged between the first interface 72 and the second interface 73 along the axial direction.

[0054] The volume of the blood return observation area 75 is meticulously designed. In this embodiment, the volume of the blood return observation area 75 is approximately 0.05 mL to 0.10 mL. This volume is a trace volume compared to the conventional dosage of 0.5 mL to 1.0 mL for a single injection via the marginal ear vein in rabbits. This trace volume will not have a measurable impact on the dosage accuracy between the injection needle and the syringe. At the same time, this trace volume is greater than the instantaneous blood return volume at the moment the injection needle enters the blood vessel, thus forming a visible red blood return signal. The axially symmetrical layout of the blood return observation area 75 allows the operator to observe the appearance of the blood return signal from either the left or right side view of the transparent connector 71. The position of the blood return observation area 75 in the middle of the fluid channel 74 avoids the blood return signal being obstructed by the connection structure of the first interface 72 or the second interface 73.

[0055] The working principle of the blood return visualization feedback component 7 is as follows. After the rabbit's ear is locally heated by the temperature-controlled imaging component 6, the marginal ear vein dilates and is visualized on the top surface of the transparent base plate 2. The operator inserts an injection needle into the target blood vessel at the top surface of the transparent base plate 2. The instant the needle tip enters the blood vessel lumen, the intravascular pressure of the rabbit's marginal ear vein forms a microsecond-level instantaneous blood return through the needle tip. The returning blood enters the fluid channel 74 through the first interface 72 and forms a static, visible red signal at the local expansion area of ​​the blood return observation area 75. The operator can observe this red signal in real time through the outer wall of the transparent connector 71 to determine that the needle tip has successfully entered the blood vessel. Subsequently, the operator administers the drug through a syringe connected to the second interface 73. The interconnected design of the fluid channel 74 allows the drug solution to pass smoothly through the transparent connector 71 without significant resistance changes. At the same time, since the volume of the blood return observation area 75 is much smaller than the single dose, it will not have a measurable impact on the actual drug dose.

[0056] The geometric parameters of the blood return observation area 75 directly affect the visualization effect of blood return. The lateral dimension of the blood return observation area 75 is designed to be 2 to 3 times the inner diameter of the fluid channel 74. This ratio ensures that the returning blood forms static sedimentation within the blood return observation area 75 and is not completely drawn back during the negative pressure operation of the syringe. It also ensures that the blood coverage area within the blood return observation area 75 is sufficient to generate a visually recognizable red signal. When the lateral dimension is less than 2 times the inner diameter of the fluid channel 74, the expansion ratio of the blood return observation area 75 is insufficient, and the sedimentation of the returning blood within the blood return observation area 75 is not obvious, making it difficult to form a recognizable red signal. When the lateral dimension is greater than 3 times the inner diameter of the fluid channel 74, the volume within the blood return observation area 75 is too large. When the operator injects the medication, the local flow rate of the medication through the blood return observation area 75 decreases, which may result in slight changes in the perceived injection resistance or medication stagnation within the blood return observation area 75, thus affecting the timeliness of medication administration. In this embodiment, the lateral dimension of the blood return observation area 75 is selected to be 2.5 times the inner diameter of the fluid channel 74, i.e., the inner diameter is 5mm, and the length of the blood return observation area 75 is 10mm. This combination of geometric parameters allows the total volume of the blood return observation area 75 to be controlled within a trace range of 0.05mL to 0.10mL.

[0057] There is a temporal synergy between the blood return visualization feedback component 7 and the temperature control imaging component 6. The temperature control imaging component 6 provides pre-injection vascular position information, i.e., the projected position of the ear vein observed by the operator through the top surface of the transparent base plate 2 before the injection needle pierces the skin; the blood return visualization feedback component 7 provides needle tip position confirmation information at the moment of injection, i.e., the red blood return signal observed by the operator through the blood return observation area 75 at the moment the injection needle pierces the blood vessel. The signals of the two components are sequentially connected but spatially independent. The temperature control imaging component 6 provides a static imaging background above the rabbit's ear, while the blood return visualization feedback component 7 provides a dynamic confirmation signal at the connection section between the injection needle and the syringe. This temporal complementarity allows the operator to instantly confirm whether the needle tip has successfully entered the blood vessel lumen through the independent visual signal of the blood return visualization feedback component 7, even if the rabbit's ear moves slightly at the moment of injection or the local thickness of the ear changes due to vascular dilation, thus avoiding the situation where the needle tip dislodges from the blood vessel due to local movement of the rabbit's ear and is not detected by the operator in time.

[0058] Example 2

[0059] This embodiment is basically the same as Embodiment 1, except that the transparent base plate 2 is made of borosilicate glass, the insulation layer 63 is 1mm thick, and the self-heating temperature of the replaceable heating element 62 is set to 41.5℃. The transparent base plate 2 made of borosilicate glass has higher thermal and chemical stability than acrylic resin, making it suitable for experimental environments requiring repeated sterilization or contact with corrosive disinfectants. When the thickness of the insulation layer 63 is set to the lower limit of 1mm, the temperature response time of the top surface of the transparent base plate 2 is shortened to 2 to 3 minutes, suitable for rapid injection scenarios where shorter operation waiting times are desired. The self-heating temperature of the replaceable heating element 62 is correspondingly lowered to 41.5℃ to ensure that the heating temperature of the top surface of the transparent base plate 2 remains within the preferred window of 38℃ to 42℃.

[0060] Example 3

[0061] This embodiment is basically the same as Embodiment 1, except that the transparent base plate 2 is made of polycarbonate, the insulation layer 63 is 2mm thick, the self-heating temperature of the replaceable heating element 62 is set to 44.5℃, and the distal end fixing member 51 and the proximal end fixing member 52 use an adjustable strap structure with nylon webbing and Velcro instead of elastic clips. The transparent base plate 2 made of polycarbonate has excellent impact resistance and toughness, making it suitable for portable applications where drop and impact resistance of the device is required. When the thickness of the insulation layer 63 is set to the upper limit of 2mm, the temperature response time of the top surface of the transparent base plate 2 is extended to 5 to 7 minutes, but the spatial uniformity of the temperature on the top surface is better, making it suitable for experimental scenarios where multiple rabbits are injected sequentially at the same time. The adjustable strap fixing member with nylon webbing and Velcro is suitable for rabbits with particularly long or short ears.

[0062] To illustrate the necessity of the various structural features of this invention, the following three sets of comparative examples are provided in this specification.

[0063] Comparative Example 1: The heat insulation layer 63 of the temperature-controlled developing assembly 6 of the present invention is removed, allowing the upper surface of the replaceable heating element 62 to directly contact the lower surface of the transparent base plate 2. In this comparative example, the heat spots on the surface of the replaceable heating element 62 are directly transferred to the top surface of the transparent base plate 2 without spatial diffusion. The temperature spatial non-uniformity of the top surface of the transparent base plate 2 increases to more than ±2°C. Areas with temperatures exceeding 42°C may appear on the rabbit's ear, significantly increasing the risk of localized burns. Furthermore, the direct transfer of heat from the replaceable heating element 62 to the transparent base plate 2 may cause localized thermal deformation of the transparent base plate 2, affecting the reusability of the device. This comparative example demonstrates that the heat insulation layer 63 plays an irreplaceable role in heat spatial diffusion and safety layering in the temperature-controlled developing assembly 6 of the present invention.

[0064] Comparative Example 2: The blood return visualization feedback component 7 described in this invention was removed. With other components remaining unchanged, the operator judged whether the injection needle had successfully entered the blood vessel solely by touch. In this comparative example, even though the auricular vein had achieved good visualization through local heating of the temperature-controlled visualization component 6, the operator still needed to rely on changes in needle-skin resistance and resistance feedback during injection to determine the needle tip position. This was especially problematic for inexperienced operators, resulting in a significantly lower first-time puncture success rate compared to Example 1, and making it difficult to identify early signs of extravasation. This comparative example demonstrates that the blood return visualization feedback component 7 provides an independent signal channel from the temperature-controlled visualization component in this invention. The parallel operation of these two signal channels improves both the timeliness and accuracy of the operator's judgment.

[0065] Comparative Example 3: The transparent base plate 2 described in this invention was replaced with an opaque white polyoxymethylene board, while keeping other components unchanged. In this comparative example, the transparent base plate 2 lost its dual functions of light transmission and support. The operator could not directly observe the projection position of the ear vein on the base plate surface from below or to the side. Vascular visualization was forced to rely solely on natural light observed from above the rabbit's ear. This upward viewing angle was significantly affected by factors such as operator hand obstruction, changes in ambient light, and residual ear hair, resulting in lower clarity of vascular visualization compared to Example 1. This comparative example demonstrates that the light transmittance of the transparent base plate 2 is as important as its support function in this invention, and the two are inseparable.

[0066] The rabbit ear vein injection auxiliary device described in this invention forms a complete closed-loop operation from support, heating, imaging, fixation, and feedback through the synergistic effect of four components: a transparent base plate assembly 1, a fixation assembly 5, a temperature-controlled imaging assembly 6, and a blood return visualization feedback assembly 7. The synergistic effect among the above four components is not a simple functional superposition, but a nonlinear synergy of multi-channel parallelism and mutual promotion.

[0067] From the perspective of the synergy between support and imaging, the transparent base plate 2 of the transparent base plate assembly 1 simultaneously serves as both a support surface and an observation plane. This integrated structural layout eliminates the need for the operator to switch visually between observing the location of blood vessels and adjusting the position of the rabbit's ear, allowing the observation and operation actions to overlap spatially. From the perspective of the synergy between support and heating, the stepped groove 4 of the frame 3 not only provides structural fixation for the transparent base plate 2 but also, together with the heat insulation layer 63 and the slot 61, forms the spatial envelope of the temperature-controlled imaging assembly 6, ensuring that the heating energy of the temperature-controlled imaging assembly 6 is fully confined within this spatial envelope. From the perspective of the synergy between heating and fixation, the vasodilation that occurs in the rabbit's ear during the heating process of the temperature-controlled imaging assembly 6 causes dynamic changes in ear thickness. The dual-ended fixation assembly 5, by independently adjusting the tension of the distal fixation member 51 and the proximal fixation member 52, can adaptively counteract the uneven local tension caused by changes in ear thickness.

[0068] From the perspective of the synergy between imaging and feedback, the temperature-controlled imaging component 6 provides a visual signal of the blood vessel position before injection, while the blood return visualization feedback component 7 provides a visual signal of the needle tip position at the moment of injection. The two signals are sequential in time and do not interfere with each other spatially. After the temperature-controlled imaging component 6 has been heated, the operator observes the blood vessel projection on the top surface of the transparent base plate 2 and aligns and inserts the injection needle. At the moment of insertion, the operator observes the blood return observation area 75 of the blood return visualization feedback component 7 to determine whether the needle tip has successfully entered the blood vessel. The above two stages of visual feedback cover the complete operation sequence from blood vessel positioning to puncture confirmation, forming two independent judgment-confirmation opportunities in a single injection process.

[0069] From the perspective of the overall problem-solution correspondence, this invention provides targeted structural solutions for the three specific technical problems described in the background art. For the first technical problem—unclear visualization of rabbit ear veins and existing solutions relying on complex optical equipment or uncontrollable chemical heating—this invention provides a passive temperature control combination scheme of a transparent base plate 2 and a temperature-controlled visualization component 6, achieving vascular dilation and visualization through passive thermal radiation; the structure is simple and the temperature is controllable. For the second technical problem—the existing device has a split between the heating element and the supporting base, posing a risk of burns—this invention provides a layered stacked structure of replaceable heating element 62, heat insulation layer 63, and slot 61, integrating support, heating, heat insulation, and safety edges into a single device. For the third technical problem—the lack of an immediate feedback channel for whether the needle has successfully entered the blood vessel—this invention provides an independent early warning structure of a transparent connector 71 and a blood return observation area 75, forming a structured channel for visualizing blood return signals between the injection needle and the syringe. A one-to-one problem-solving mapping relationship is formed between the above three specific technical problems and the technical solutions of this invention.

[0070] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention. The rabbit ear vein injection auxiliary device described in this invention is not only applicable to rabbit ear vein injection scenarios, but can also be used with structural and dimensional adaptations for superficial vein injection scenarios in other experimental animals such as rats and guinea pigs. Such derivative applications still fall within the scope of protection of the present invention.

Claims

1. A rabbit ear vein injection auxiliary device, characterized in that, The system includes a transparent base plate assembly (1), a fixing assembly (5), a temperature-controlled imaging assembly (6), and a blood return visualization feedback assembly (7). The transparent base plate assembly (1) includes a transparent base plate (2) and a frame (3). The transparent base plate (2) is made of a light-transmitting material. The frame (3) is arranged along the outer edge of the transparent base plate (2). The inner side of the frame (3) is provided with an annular groove (4). The outer edge of the transparent base plate (2) is embedded in the groove (4). The top surface of the transparent base plate (2) is lower than the upper edge of the frame (3). (3) The inner upper edge is provided with a rounded corner transition part; the fixing component (5) includes a distal end fixing part (51) and a proximal end fixing part (52), the distal end fixing part (51) and the proximal end fixing part (52) are respectively disposed on both sides of the transparent base plate component (1), the distal end fixing part (51) and the proximal end fixing part (52) are used to fix the distal end and proximal end of the rabbit's ear respectively; the temperature control developing component (6) includes a slot (61), a replaceable heating element (62) and a heat insulation layer (63), the slot (61) Located below the transparent base plate (2), the replaceable heating element (62) is detachably inserted into the slot (61), the heat insulation layer (63) is located between the transparent base plate (2) and the replaceable heating element (62), the replaceable heating element (62) locally heats the transparent base plate (2) through the heat insulation layer (63) to make the peripheral auricular vein of the rabbit ear dilate and become visible; the blood return visualization feedback component (7) includes a transparent connector (71), the transparent connector (71) is located between the injection needle and the syringe. Between them, one end of the transparent connector (71) is provided with a first interface (72), and the other end of the transparent connector (71) is provided with a second interface (73). The first interface (72) is connected to the injection needle, and the second interface (73) is connected to the syringe. A fluid channel (74) is formed inside the transparent connector (71). The fluid channel (74) connects the first interface (72) and the second interface (73). The fluid channel (74) partially expands in the middle of the transparent connector (71) to form a blood return observation area (75).

2. The rabbit ear vein injection auxiliary device according to claim 1, characterized in that, The groove (4) is a stepped support groove with the opening facing upward. The groove (4) includes a horizontal support surface that supports the outer edge of the transparent base plate (2) and a vertical inner wall that abuts against the side of the outer edge of the transparent base plate (2). The portion of the vertical inner wall that is higher than the top surface of the transparent base plate (2) together with the top surface of the transparent base plate (2) forms a locking position. The locking position is used to accommodate and limit the edge of the rabbit's ear.

3. The rabbit ear vein injection auxiliary device according to claim 2, characterized in that, The heat insulation layer (63) is a silicone heat insulation layer with a thickness of 1 mm to 2 mm.

4. The rabbit ear vein injection auxiliary device according to claim 3, characterized in that, The inner wall of the slot (61) is provided with an anti-slip structure (64). The anti-slip structure (64) is an array of micro-protrusions or an array of grooves that contacts the back of the replaceable heating element (62). The array of micro-protrusions consists of multiple protrusions arranged along the inner wall of the slot (61), and the array of grooves consists of multiple recesses arranged along the inner wall of the slot (61). The anti-slip structure (64) and the back of the replaceable heating element (62) form a geometric fit.

5. The rabbit ear vein injection auxiliary device according to claim 4, characterized in that, The replaceable heating element (62) heats the transparent base plate (2) through the silicone heat insulation layer, so that the top surface of the transparent base plate (2) forms a local heating temperature of 38°C to 42°C.

6. The rabbit ear vein injection auxiliary device according to claim 5, characterized in that, The distal end fixing member (51) and the proximal end fixing member (52) are spaced apart from each other along the length direction of the transparent base plate assembly (1), and the distal end fixing member (51) and the proximal end fixing member (52) are independently adjustable.

7. The rabbit ear vein injection auxiliary device according to claim 6, characterized in that, The volume of the blood return observation area (75) is set to make the instantaneous blood return visible after the injection needle enters the blood vessel, and the volume of the blood return observation area (75) does not change the injection dosage accuracy between the injection needle and the syringe.

8. The rabbit ear vein injection auxiliary device according to claim 7, characterized in that, The blood return observation area (75) extends along the axial direction of the fluid channel (74), and the blood return observation area (75) is symmetrically arranged between the first interface (72) and the second interface (73) along the axial direction.

9. The rabbit ear vein injection auxiliary device according to claim 1, characterized in that, The replaceable heating element (62) is a constant temperature heating pad, and the working surface temperature of the constant temperature heating pad is constant within a set range.

10. The rabbit ear vein injection auxiliary device according to claim 1, characterized in that, The transparent base plate (2) is made of one of acrylic resin, polycarbonate or borosilicate glass.

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