Most reptile species that are kept as pets are subject to predation in the wild. As potential prey, they have adopted the survival strategy of trying to appear fit and healthy to avoid being eaten. This evolutionary strategy is sensible in nature since an animal that appears to be sick or weak or abnormal in appearance is easier to catch.
To make matters more complicated, reptiles have a limited number of ways to show that they are ill. So, the most important thing to remember when evaluating the health of your pet reptile is that he doesn't want you to know that he is unwell. Consequently, by the time you are sufficiently concerned to seek veterinary advice, your pet may have been ill for a relatively long time, and disease may have progressed further than is immediately clear.
Good preventive health care should be the goal of every reptile owner. This involves researching the natural environment of the species – its habitat, diet and particular requirements in captivity. Regular veterinary visits are strongly recommended and screening blood work, examination for parasites and husbandry reviews can be performed as appropriate. In spite of the best care, however, some pets can become ill and early recognition of a problem is often crucial to the outcome of the case.
What is Normal?
The most important thing for you to know as owner of a pet reptile is what is the normal appearance and behavior for its species. Only when you know what is normal will you be able to recognize what is abnormal.
To educate yourself about the normal appearance and habits of your reptile species: subscribe to hobby magazines, visit zoos and reptile shows, join a local reptile club, and refer to recent books that have good color illustrations. Nature programs on television often have excellent footage of animals in the wild. Observing your species of reptile, reading and speaking to experienced reptile keepers will greatly improve your ability to recognize a problem quickly. A good reptile veterinarian is also an invaluable source of current and practical advice.
Do not rely on a pet store for assurances as to what is normal. While many pet shops are ethical, they often have employees with no more knowledge than the average customer. Remember that you don't need to know anything about animals to be allowed to sell them.
Once you have a sound knowledge of your pet's environmental, nutritional and medical needs, you can begin to assess his health. Assess the following on a regular basis:
Activity level: increased or decreased? An unusually docile or aggressive lizard or snake may be ill or in pain.
Hiding: A stressed or sick reptile or one in pain may spend more time in hiding. Instinct tells him not to show himself to potential predators.
Posture and responsiveness: When you enter the room, does your lizard notice and stand? Does your tortoise wander to the cage side for a scratch? Does your snake or turtle seem aware of you? Since most of these animals are vulnerable to predation in the wild, they should be aware of movement and activity in the environment. Eyes should be bright and alert, and those species with eyelids should seldom have them closed. Reptiles that lie in one spot all day, that seem reluctant or unable to move, or that cannot hold their legs, tail, head or body in a manner normal for the species, may be ill. Some species, especially snakes, may normally be relatively sedentary, but again, you must know what is normal for your pet.
Gait: Is your lizard, turtle or tortoise using all its limbs normally? Watch nature programs on television and gain an appreciation for the normal movement patterns of reptiles in the wild.
Color: Some species display a wide variety of normal color variations, but generalized or patchy changes may indicate a problem. Be familiar with the normal.
Shape: Is your snake or lizard swollen in its body or limbs?
Appetite: Has your pet's appetite increased, decreased or become selective (i.e. picky eater)?
Drinking: Drinking habits vary with species, but increased thirst may point to a variety of possible problems, particularly with tortoises and some lizards.
Urine and stool production: Generally speaking, reptile waste has three components: a clear, liquid urine, a chalky white urate (both products of the kidney), and a blackish-brown fecal material. In most cases they are evacuated together. When reptiles are housed in relatively unchanging captive conditions, are fed at regular intervals and are kept in an optimal environment, their bowel movements can become highly predictable.
When clearing away feces and urine, take some note of the appearance. Is there more or less than normal? Is the stool of the usual consistency? Are the urine clear and the urate chalky white? Does either have a yellow, green, orange or brown tinge to it? Is there any blood? Does the animal appear to have difficulty in passing feces or urine, such as straining, passing only small quantities at one time, or passing waste with increased or decreased frequency.
Other Normal Characteristics
Skin: Generally, snakes should be smooth, without wrinkled scales or retained skin. Check your snake after each shed. There should be no evidence of retained eyecaps, raised or blistered scales, or red, sore appearing areas. The underside should appear healthy, not red and inflamed or moist. Burns to this area are common when hot rocks are used and they are not recommended.
Tortoises and turtles should have hard shells, without swellings, soft spots, or areas of white or pink discoloration. Lizards, snakes and the soft parts of tortoises and turtles should be free of swellings under the skin, sores and areas of discoloration. Mites appear as very small spots between scales on the head. Species with toenails should be checked for proper wearing; constricting bands of unshed skin can accumulate around the toe, leading to strangulation of the digit.
Eyes, ears (for those who have them), nostrils, mouth and vent: There should be no discharge or bubbles from the eyes or nose, although a salt-like discharge is normally sneezed from the nose of some reptiles, such as the green iguana. There should be no sores or scabs on the nose – this is a particularly common problem of captive lizards and snakes. There should be no foam or red/discolored patches in the mouth.
Your reptile should breathe quietly -- wheezing or a squeak or whistle may indicate respiratory disease and should be investigated. Distinguishing between abnormal respiratory sounds and those related to an aggressive display is not always easy, but your veterinarian will be able to help you.
Swellings in the area of the ear are often seen in turtles and tortoises. These can be caused by abscesses.
Nutritional problems often cause the animal's conformation or shape to be abnormal. For example, a herbivorous reptile, such as the green iguana, often develops a swollen jaw when it is malnourished. The jaw of a healthy iguana should be firm, not rubbery. In the case of tortoises and turtles, beaks can overgrow and become deformed. The vent should be clean on the outside – soiling may indicate diarrhea or another condition.
Body condition: Obesity is as dangerous to your pet as being underweight. Be familiar with the appearance of a well-fleshed member of your pet's species and have your veterinarian explain assessment of body condition for your particular species. Weigh your pet regularly and record the number.
For more information on how to tell if your reptile is sick, see When Your Reptile Behavior is Abnormal and The Iceberg Principle.