Rabbits are especially susceptible to the effects of stress and are easily injured by careless handling. They are usually non-aggressive animals, but when frightened they may make violent attempts to escape. Occasionally an aggressive individual that attacks the handler and attempts to bite or scratch will be encountered. Such animals are generally easily controlled by applying the restraint techniques described below rapidly and firmly. Rabbits have powerful hind legs equipped with sharp claws which can produce painful scratches.
To restrain a rabbit, grasp it firmly by the skin overlying the neck. Under no circumstances should the animal be restrained by grasping its ears. Some handlers include the ears in their grasp when holding the scruff. This is acceptable provided that no tension is placed on the ears, but an owner or untrained person observing the procedure can easily misinterpret the means of restraint and assume that the rabbit is being lifted by its ears. For this reason, it is recommended that the ears should not be grasped when restraining rabbits.
Following initial restraint by grasping the scruff, the handler’s other hand should be placed around the hindquarters. If the animal struggles, the handler’s forearm can be positioned along the line of the back to prevent the animal from moving.
The rabbit can then be lifted clear of its box and positioned with its head tucked under the handler’s arm and with its hindquarters and back supported. These precautions are necessary to minimise the risk of the animal kicking out when lifted. If this occurs, the rabbit is likely to fracture or dislocate its lumbar spine, and may also injure the handler. It is also important to support the animal’s back as securely as possible when placing it onto an examination table.
A common error made by inexperienced handlers is to release the animal before it is fully in contact with the ground. This can cause the animal to kick out and struggle, and once again can result in the animal injuring itself. When returning a rabbit to its cage or transport box, the handler should ensure that both his arms are withdrawn simultaneously, to avoid being scratched by the animal. When placing a rabbit in a cage, position the animal so that it faces one of the side walls. If the rabbit is released whilst facing the back of the cage and it kicks with its hind legs, then it could injure the handler, or send a shower of sawdust and faeces into his face.
Restraint for injections or blood sampling can also be achieved by wrapping the rabbit in a surgical gown or lab coat.
Oral administration
The technique adapted for oral dosing of rabbits will be dependent upon whether administration of accurate volumes of fluid is required. It is possible to administer fluids quite simply by restraining the rabbit on a firm surface and placing the nozzle of a syringe in the corner of the mouth. The material should be injected slowly, in 0.25-0.5 ml boluses, allowing time for swallowing between each mouthful. Some material may be spilt during this procedure, but provided it is relatively bland most will be taken quite readily. Accurate volumes can be administered using a stomach tube, but a gag must be used in this species unless the animal is anaesthetised.
Subcutaneous injection
Subcutaneous injections are easily carried out in rabbits and often require only minimal restrain in animals of good temperament. The rabbit should be placed in a suitable transport box or restraining device to limit its movements and the skin over the neck grasped with one hand. Material can then be injected into the tented skin with little difficulty. If large volumes (>5 ml) are to be injected, it is advisable to have an assistant to restrain the animal on a firm surface. Following injection under the skin of the neck or back, the needle can be withdrawn slightly and redirected to spread the fluid over a wider area.
Intraperitoneal injection
If assistance is available, the rabbit should be restrained as shown in Fig. 8. The xiphisternum and pubis should be palpated at the anterior and posterior extremes of the abdomen, the needle being introduced at right angles to the abdominal wall, just lateral to the midline, at a point equidistant between the xiphisternum and pubis. This positioning should avoid accidental puncture of the bladder or stomach. A short (2.5 cm) needle should be used. Puncture of the viscera is a rare complication. If no assistance is available, the rabbit should be placed on a firm surface and restrained by grasping the skin over the neck. The injection should be made at a point just anterior to the hind limb in the lower third of the abdomen. This is a less satisfactory technique since sudden movement by the rabbit could lead to incorrect positioning of the needle, possibly damaging the abdominal viscera.
Intramuscular injection
The most usual sites for intramuscular injection are, as with other species, the posterior and anterior thigh. The larger size of the blood vessels within the muscle masses in this species compared to small rodents makes inadvertent intravenous injection a possibility. To avoid this potential complication, following introduction of the needle into the muscle mass, the plunger of the syringe should be drawn back to confirm that no blood can be obtained.
To inject into the hind limb muscles, an assistant should restrain the rabbit on a firm surface and the operator should grip the muscles of the anterior or posterior thigh between the thumb and forefinger. The needle should then be introduced at right angles to the skin surface into the centre of the muscle mass. Injection can also be made into the dorsal lumbar muscles.
Intravenous injection
Intravenous injections are easily carried out in rabbits, the marginal ear veins being the vessels of choice. An assistant should restrain the rabbit, or if an assistant is unavailable, the animal can be restrained by wrapping it in a towel or laboratory coat, with the head protruding. Provided that the animal is securely wrapped, it will readily accept this method of restraint and will not struggle. Both of the operator’s hands are then free to carry out an intravenous injection.
Wrapping the animal in this way provides good restraint and supports the rabbit’s back, and is generally preferable to using a rabbit restraining box. If one of these restraining devices is used, it must be of an appropriate size for the rabbit. If the device is fitted with a neck yoke, it is preferable to avoid using this attachment because of the risk of injury to the rabbit if it struggles whilst in the restraining device.
The hair overlying the vein should be shaved with a scalpel or razor, so that the vessel becomes clearly visible. If assistance is available, then the vein should be compressed at the base of the ear, so that it dilates along the remainder of its length.
The ear should be held firmly in one hand and the needle held almost parallel to the vein and directly above it. It can then be gently introduced into the vein and advanced about 1-2 cm along the lumen. It may be found easier to use a “butterfly” infusion set for intravenous injection, rather than a needle fixed directly to the syringe.
Many rabbits will twitch or jump as the needle is pushed into the ear, and the flexible coupling between syringe and needle provided by a “butterfly” infusion set enables the needle to be maintained in its position in the ear without pulling on the syringe.
If repeated injections are to be made, an indwelling catheter (eg Abbocath, Quickcath) should be taped in place. Pain on venepuncture, and the consequent movements of the rabbit, can be prevented by use of local anaesthetic cream (EMLA, Astra, Flecknell et al, 19901). The cream is applied over the vein on the shaved ear, and covered, with an occlusive dressing. (After 30-45 minutes, the dressing is removed, and the ear wiped clean, and venepuncture carried out.
Alternative sites of injection include the cephalic vein and the medial saphenous vein, however these are relatively mobile vessels, and more difficult to use successfully.