Dr. Jenni Bass
The loss of a pet is never easy and almost always presents questions to owners and veterinarians alike, as to why exactly the animal died or reached the point at which euthanasia was necessary. In the case of reptiles and other "exotic" pets, the prevalence of underlying, undiagnosed or poorly understood disease is high. Many of these species have not been in the pet trade for long, so their normal physiology, dietary and environmental needs may not be fully known. Our understanding of some species has grown to the extent that they no longer commonly die simply because we don't feed them properly, instead they are living long enough to develop the illnesses to which all animals become more susceptible with age. An example is the green iguana. Fifteen or twenty years ago, when they were commonly fed cat food, these plant eating lizards suffered from disease conditions related to high fat and protein levels, and a lack of calcium and plant fibre. They died young of metabolic bone disease and kidney failure. Now it is not unusual for iguanas to reach ten or twelve years of age, and the pattern of illness is shifting toward more longstanding, degenerative disease, which shows greater promise for treatment than the acute or sudden organ failure of iguanas in the past.
Necropsy is the term used to refer to an autopsy or post mortem examination performed on a non-human animal. Ideally, a necropsy should be performed on all pet reptiles which die or are euthanised. A great deal can be learned from the procedure and this knowledge will be beneficial, directly or indirectly, to owner, veterinarian and to other reptiles. The nature of medicine is such that in a few cases we cannot reach a final diagnosis, except with a necropsy. A gross post-mortem (what can be seen with the naked eye) is usually the first step, and this may be sufficient. In some cases, microscopic, toxicological or other sophisticated laboratory techniques may be required.
Reasons to Allow a Necropsy
The reasons to consider allowing a necropsy to be performed on a captive reptile vary with the situation. The owner of a single iguana has different concerns than does a hobbyist who breeds boa constrictors and occasionally looks after his friend's pythons. The keeper who cares for several species from many natural habitats and who may have very valuable animals moving through his premises stands to lose financially if he does not understand the general health of the collection. Your reptile veterinarian should be able to explain to you what a necropsy may teach you in your particular situation, as well as be able to outline the limitations.
Every necropsy will further the owner's and the veterinarian's understanding of the species. Reptile medicine is sufficiently new, and encompasses so many species that even the most experienced practitioner will periodically find something which he has never before seen. This may be a novel disease process, or a normal feature which he has never seen. The veterinarian may simply make a mental note of the finding, and it may help to distinguish normal from abnormal in a future case. He will frequently discuss findings with other exotic pet practitioners, and he may even publish the finding. It is important to realize that in most cases, significant discoveries will reach well beyond your veterinarian.
Having experienced the loss of a pet, many owners find some comfort or relief in the knowledge that nothing more could have been done. If there are other pets at home, there may be a concern regarding infectious disease. If the disease was a reflection of husbandry practices, a necropsy may provide solid evidence of the need to make changes and may give clues as to the health of any other pet reptiles.
Captive reptiles often suffer from two or more disease conditions. One disease process may overshadow another. It may be difficult or impossible to diagnose each condition in the live animal. This may be a reflection of the animal's size, temperament, degree or nature of illness, lack of available testing or financial constraints.
Reptiles can be affected by a number of zoonoses (diseases transmissible from non-human animals to man). Particularly if there are immune compromised individuals in the home, it may be extremely important to be certain that the reptile was or was not affected by a given disease (such as the bacteria Salmonella).
If a reptile is one of a large collection experiencing disease, it may be prudent to sacrifice an individual showing signs representative of the condition, in order to reach a diagnosis. This is especially the case when infectious disease is suspected. Some diseases, such as those affecting the central nervous system, can be difficult to diagnose definitively in a live animal. When there are no simple blood or tissue tests and a large collection is at stake, the sacrifice of one animal may be the most expedient means of reaching a diagnosis, on which the well-being of many animals may rest.
Some diseases, particularly viruses, are notoriously difficult to eradicate from a collection, due to the presence of carrier animals. These are animals that may harbour the disease, infect other animals, and yet show no signs of illness themselves. Some diseases may lie dormant within the animal for months or years. When faced with the possibility of unknown disease within a collection, selective necropsy is sometimes the best choice.
The nature of the disease must also be considered. Some viruses, bacteria and parasites are difficult to transmit between animals and are easily eliminated from the environment with sound hygiene practices and treatment of the animals. Other agents of disease are extremely tough, requiring very aggressive disinfection procedures, replacement of equipment, and in some cases, depopulation and replacement of the collection. When the lives of the animals are at stake, not to mention financial and labor investments, the development of a logical plan requires a definitive diagnosis.
When a collection of reptiles is involved, post mortem or necropsy data may appear particularly useful in hindsight. When mortality patterns and necropsy findings are analysed, they may reveal trends in deaths or illness. Over weeks, months or years it may be possible to make associations with changes in such factors as diet, lighting, season or a variety of other housing and husbandry parameters, which may show effects over relatively long periods.
In the event that a necropsy is not performed, it may be advisable to store the body of the reptile (frozen). This is a form of "insurance", in case of further deaths. The identity of the animal should be recorded, as should the date and manner of death, as well as any information about behavioural or physical changes and veterinary care. It is easy to forget and mix up individuals; good records are an invaluable resource when it comes to understanding the dynamics of a disease process or husbandry.