Introduction to Reptile Medicine

Captive reptiles can be found in zoological institutions, the pet trade, commercial farming, universities, and laboratory animal facilities. Along with the prevalence of captive reptiles, there is a higher demand for improved welfare and veterinary care. As veterinarians, it is our duty not only to provide high-quality medicine but also to serve as a source of reliable information and education for reptile owners and keepers. Veterinary care of reptiles must include education on proper husbandry and nutrition, two critical factors that influence the health of reptile patients. To be successful in this endeavor, we must understand the reptile market and the demographics of reptile owners and keepers. According to a 2019-2020 report by the American Pet Products Association, reptiles comprise approximately 4.5% of the pets owned by households in the United States. The Federation of British Herpetologists claims that the number of pet reptiles in the United Kingdom may surpass that of dogs and cats, but it is difficult to find supporting data for these claims across European countries. Nonetheless, it is well known that the reptile trade is strong and thriving in Europe as well as in the United States. Of interest is the age distribution of reptile owners in the United States. Fifty-three percent of reptile owners are in the "gen Y" (1994-1980) generation followed by 26% "gen X" (1979-1965), 19% "baby boomers" (1964-1946) and 2% "builders" (1945-1920).

Not surprisingly, the majority of reptile owners rely on the internet to obtain information about reptile care. The second most common source of information is pet store employees, while only 21% rely on veterinarians. This should be a clear indication that veterinarians need to be more proactive in reaching out a to the reptile-owning generations in ways that they can relate to so they can build up clientele and improve the welfare of captive reptiles. This requires a paradigm shift in which veterinarians seek out promoting and advertising opportunities to make the public aware of their services. Many reptile-owning individuals are not even aware of all the veterinary services available for reptile species. If these individuals were more aware and developed a relationship with veterinarians, we would be more likely to have a positive impact on the captive care and welfare of reptiles. While there may be varying degrees of the bond that humans form with reptiles, most reptile owners are very appreciative of veterinarians willing and able to care for their pets. Veterinarians should offer the same standard of care to reptiles as they do to other species and charge accordingly for their time and services.

With over 10,000 species of reptiles, it is impossible to know the proper care for all species. Instead, the focus should be placed on becoming knowledgeable about the more common species that one will be working with in the course of practice. The commonality of species may vary with geographical location; nonetheless, some species such as bearded dragons, ball pythons, and sulcata tortoises are overrepresented in the pet trade.

The first approach to learning about reptiles is to think in terms of their biology. Reptiles are not domesticated species and still retain many of the behaviors observed in their natural environment. Being familiar with their natural history and biology will facilitate their captive care and treatment. In order to understand reptiles, one must be able to correctly identify the species and be familiar with their country of origin, climate, habitat, dietary scheme, photoperiod, and natural behaviors. Field guides and books have an abundance of information to help identify species and their environment.

Knowing the country and climate in which reptiles live will help to differentiate tropical from temperate and desert species. This information will directly influence their temperature requirements and photoperiod. Tropical and desert species will require higher environmental temperatures and will have longer photoperiods as compared with temperate species. Their habitat can also be divided into arboreal, aquatic, terrestrial, and fossorial (live underneath leaves and shallow layer of soil). Many species cross between habitats but will have a preference for one and feel most comfortable in it. For example, green iguanas are an arboreal species but spend time on the ground searching for food and during the breeding season. When they are done foraging and at the end of the day, they roost in trees where they feel more comfortable high off the ground away from predators.

An important consideration is the natural patterns of activity according to photoperiod. Diurnal species are active during the day and should be fed during the day to allow ample time to ingest food. Nocturnal species should be fed at dusk, dawn, or during the night, when they are more active and likely to be on the search for food. Knowing their dietary scheme is another important aspect of reptile biology. Reptiles can be omnivores, herbivores, insectivores, or carnivores. Providing high quality nutrition according to their dietary scheme is essential for good health and a primary challenge in captivity. Omnivores should be fed high-quality commercial diets in combination with fresh produce. Carnivores should be fed whole, pre-killed prey items of appropriate size. Herbivores should be fed a variety of fresh produce, grasses, and hays, in addition to a high-quality commercial diet. Insectivores should be fed a high-quality commercial diet in addition to a variety of invertebrates. In Europe, there is a wider variety of commercially available invertebrates compared to the United States. In order to offer a wide variety of invertebrates in the United States, owners are primarily restricted to purchasing through online retailers.

Finally, one must also be aware of the behavior and personalities of different reptile species. Green iguanas are very gregarious animals living in large groups under constant struggle for territory. Therefore, iguanas maintained alone will show similar behaviors expressed as a willingness to share space and time with the owner but also establishing clear territory demarcations. Adult male iguanas can become very aggressive and territorial during the breeding season. Snakes, on the other hand, tend to be solitary and show aggressiveness as a sign of defense and fear, not as an effort to establish territory. Turtles and tortoises can be solitary or gregarious and, for the most part, are very timid. Being familiar with these aspects about each group of reptiles will help you design a plan for restraint as well as make appropriate husbandry and dietary recommendations.

A thorough knowledge of the anatomy of reptiles is essential for interpretation of physical exam, diagnostic tests, and during surgical procedures. The skin of most reptiles is covered with scales; in some species there are osteoderms, or bony plates under the scales. The mucous membranes of reptiles are usually lighter in color than mammals and can be somewhat tacky, making assessment of hydration status more challenging. In addition, some species have pigmentation of the oral mucosa. For example, bearded dragons have a yellow coloration of the mucosa in their oral cavity. The position of the eyes may help in assessing hydration status, but some species (e.g., chameleons) are able to voluntarily retract their eyes, which negates eye position as an indication of dehydration. Some reptiles have eyelids, while others rely on spectacles (a skin layer covering the eye) to protect the cornea. Reptiles may have pleurodont or acrodont teeth. Pleurodont teeth have no socket, attach on the lateral aspect of the mandible, and are replaced throughout life. Acrodont teeth have firm attachments via sockets and are not replaced. Extra care must therefore be taken when examining the oral cavity of reptiles with acrodont teeth (e.g., chameleons and agamids). The tongues of reptiles range from a moveable structure (e.g., snakes, monitor lizards) to a fixed structure (e.g., crocodilians). Green iguanas have a red to purple coloration on the tip of their tongue, which is normal and must not be confused with trauma or necrosis. The musculoskeletal system is also very different, with some having no limbs (e.g., snakes) while some have additional adaptations such as prehensile tails (e.g., chameleons) and tail autotomy (e.g., green iguanas).

Reproduction of reptiles occurs primarily as vivipary (give birth to live young) or ovipary (lay eggs). Some species are parthenogenic (asexual reproduction, species are females only). It is important to know that intact reptiles may show reproductive behaviors even in the absence of a mate. This is especially important in oviparous species, which can develop and lay infertile eggs, to the surprise of the owner. It is important to ensure proper calcium intake in these species to prevent dystocia problems. Some species will also decrease their activity and will eat less or become anorectic during certain times of the year, all associated with reproductive activity.

Knowledge of internal anatomy is critical for surgery and radiographic interpretation. Reptiles do not have a diaphragm, so the viscera and the lungs are found within the same cavity, the coelomic cavity. Radiographically, the lungs may be observed to occupy over 50% of the coelomic cavity, especially during inspiration. The detail of the viscera is usually less rewarding, and the goal is to identify any well-demarcated masses that may appear out of place within the cavity. In females, follicles and/or eggs may be...