26 Apr 2010
William Lewis
Job Title
William Lewis explains that these smaller patients need the same sympathetic and humane consideration when approaching euthanasia as larger animals
AS veterinary surgeons, we are often called upon to euthanise animals. The growth in popularity of rabbits, small mammals and exotic pets, such as reptiles and birds, means we are also more frequently faced with the prospect of euthanising these small patients.
I believe we have a moral and ethical responsibility to both the animal and client to perform euthanasia in a respectful and painless manner. We do this for dogs, cats and horses, therefore, there is no reason why small pets should not be afforded the same level of respect and care.
It may be a controversial statement, but I believe that following some of the information provided in textbooks may not be the most humane and palatable way of dealing with these patients. Much of the information is gleaned from work on laboratory animals, and I feel our clients expect and demand a more sympathetic approach to dealing with the euthanasia of small mammals and exotic pets.
The small size of many of these patients, and an unfamiliarity with their anatomy, certainly makes this a considerable challenge for most small animal practitioners. A number of clients have joined our practice as a result of unsatisfactory euthanasias performed by other veterinary surgeons. This frequently involved a jab into the peritoneum, liver or thoracic cavity, with considerable discomfort to the patient and often a prolonged time until death. Needless to say, this is completely unacceptable to the owners of these pets, who may value them as much as cats and dogs are valued by their owners. I accept that owners’ perception may be worse than the reality, but I think we can, and should, be seen to approach euthanasias in a more sympathetic (and possibly humane) fashion.
I have a large exotics caseload and, consequently, experience of euthanising these animals. Therefore, I would like to share some of the methods I use – including photographs to aid with the anatomy – and, hopefully, encourage practitioners to consider more humane and acceptable methods of euthanasia.
Wherever possible, I attempt intravenous euthanasia. At times, this may require the addition of anaesthetic with gas to achieve a quick and painless result. This will also be a valuable method in learning how to draw blood from these patients, if ever required, as the technique is the same, but in reverse. If intravenous access is not possible, then intracardiac euthanasia under isoflurane anaesthesia is performed.
• Rabbits
Rabbit owners often request to be present with their pets at the time of euthanasia, and this can be a particularly difficult and stressful time for vets. I recall a rabbit I tried to euthanise by using its ear vein, and everything going horribly wrong; the rabbit screamed in distress and there was a lot of bleeding, which created a very stressful situation for all concerned. As a result, the client wrote a letter of complaint to the practice principal.
I now place an intravenous catheter in the marginal ear vein and attach a butterfly giving set, so owners can hold their rabbit if they so desire (Figure 1). Euthanasia can then be performed calmly and painlessly. I use the purple 26-gauge catheters, inserted into the marginal ear vein. This is extremely easy to do as the vein is stable and easily visible. A small amount of surgical glue is used to attach the wing of the catheter to the pinna, and tape is wrapped around the ear to keep everything in place.
Our nurses are now trained to insert these catheters. I let the client hold the rabbit, and then I attach a butterfly catheter to the intravenous catheter. Once this is all in place, I can administer the Euthatal injectable solution without touching the rabbit.
Small mammals and ferrets are masked down with isoflurane and injected intracardiac. The same applies for wild hedgehogs and other small wild mammals, such as moles, mice and shrews.
• Birds
Birds are an interesting challenge. Small birds, such as canaries, budgies and other parrots are anaesthetised with isoflurane and injected into the right jugular vein. This is accessed by laying the bird on its left side and parting the feathers on the right side of the neck. The head is placed between the index and middle fingers, and the thumb is used to raise the vein in the ventral neck area – a naturally featherless area called the apteria (Figure 2). The jugular is surprisingly large and easily accessed in birds weighing as little as 15g.
This technique is quite quickly mastered – I started by practising on injured wild birds. It works well for parrots, softbills, chickens (Figure 3) and ducks. Pigeons seem to have a lot of fat and thick skin on the neck, and the technique is not quite as easy to perform on them.
Learning this technique will also allow you to draw blood samples from small birds – impressing your clients and staff alike. The medial metatarsal vein (Figure 4) also runs across the medial aspect of the distal limb, and can be particularly easily accessed in ducks. The ulnar vein that runs on the underside of the wing (Figure 5) can be used if neither of the above can be accessed for any reason.
• Reptiles
Reptiles can present a few more problems. Larger lizards, such as bearded dragons and iguanas, can be injected into the ventral tail vein (Figure 6). The patient is placed in dorsal recumbency and a needle is inserted exactly on the midline – aiming to hit the tail vertebrae. The vein runs along the ventral surface of the vertebrae and is easily accessed (Figure 7).
Smaller lizards can be masked down with isoflurane and injected in the heart or liver.
Tortoises can provide a challenge, but have three vascular areas that may be accessed: the dorsal tail vein, jugular vein or, more readily, the subcarapacial sinus (Figure 8). The latter is accessed by taking a 1-1.5in needle and bending it at about 45°. The head of the tortoise is pushed right into the shell and the needle is inserted at the junction of the skin and carapace above the head. Direct the needle upwards towards the spine and you will access a large venous sinus.
Confirming that tortoises are deceased can be a challenge. We now use a Doppler probe, inserted alongside the neck, and pushed as far inwards as possible, aiming towards the heart.
Snakes can also provide a challenge, but there are two techniques I routinely use. The heart lies at about 20-35 per cent of the distance between the head and cloaca. If the snake is turned in dorsal recumbency, the heart can be seen beating somewhere in this area. If you cannot locate it, use a Doppler to localise it. Placing the thumb of your left hand caudally to the heart, and the index finger cranially to the heart, will stabilise it, and the injection may be given directly intracardiac.
Larger snakes, such as Burmese pythons, can be a little more challenging. I anaesthetise them with isoflurane as follows. The mouth is opened with a tongue depressor and some Intubeaze is sprayed on the glottis. Once this has relaxed, the mouth is opened again ( tongue depressors are useful for this) and an endotracheal tube of appropriate diameter is inserted through the glottis (Figure 9) and the mouth is then closed and held tightly shut. Manual ventilation with isoflurane at five per cent will induce anaesthesia, and the intracardiac injection can be administered. If intubation is too difficult, or you have problems handling these large snakes, consider sedating them with drugs – for example, medetomidine, ketamine or Zoletil. Hypothermia (placing a reptile in a fridge or freezer) is not an appropriate method of euthanasia in this day and age.
• Fish
Fish are another species that may cause anxiety for the practitioner. These consults may be handled in one of two ways. If the client wishes to euthanise a small fish at home, you could suggest a number of options. Eugenol (clove oil) may be added to the water at a dose of at least 10 drops per litre of water. Mixing it with a bit of warm water helps to disperse the agent more evenly.
Another option is Alka-Seltzer tablets (sodium bicarbonate). Use two tablets per half litre of water and leave the fish in the water for more than 10 minutes after the point at which respiration has stopped.
Koi calm drops can be bought from commercial fish dealers. Ten drops in two pints of water is the dose used for euthanasia.
For larger fish, and for those presented to our surgery, I use tricaine methanesulfonate (MS-222) (Figures 10 and 11). This is a powder that can be added to water, and used in anaesthesia. One quarter of a teaspoon is used per two pints of water. The fish should be left in this solution for at least 10 minutes beyond the point at which respiration has ceased.
Once the fish is anaesthetised, I remove it from the water and inject pentobarbitone intracardiac (Figure 12), or in the caudal vein of the peduncle (tail). This is approached laterally and runs along an almost visible line in the middle of the tail overlying the vertebrae. In some larger fish, it may be possible to inject intravenously in the veins on the medial side of the operculum (gill cover).
There is no excuse for your patients to feel any pain or discomfort when being euthanised. The experience should also not be a stressful one for the owner.
Owners are a lot more demanding these days, and have a right to ensure euthanasia is carried out painlessly, humanely and respectfully. I would challenge everyone to start practising these methods – it will certainly make your life a lot easier, improve client relationships and potentially avoid distressing and stressful situations.
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