Melissa Kaplan's
Herp Care Collection
Last updated January 1, 2014

Signs of Illness and Stress in Reptiles

©1997. 2002 Melissa Kaplan


There are many factors that go into making and keeping a reptile healthy. Internally, they must be healthy, with all systems functioning properly. While they may not be completely parasite- or infection-free, a healthy animal's immune system functions strongly and easily keeps the colonies of parasites, bacteria, or fungi under control so that they do not reproduce to such an extent as to interfere with the normal functioning of the body. The skin of a healthy animal looks right for its species. For most reptiles, this means well rounded and filled out, with few or any the lateral folds associated with dehydration. The color is full and clear. A healthy animal behaves normally for the species, alert to its surroundings, thermoregulating during the course of the day, eating, drinking, and defecating on a regular basis based on normal circadian rhythms and digestive cycles. Shedding is regular, occurring every 4-6 weeks or so, sometimes more often for younger animals during the peak growing seasons during the year, more slowly during any annual slow period (for example, the period of most rapid growth for most reptiles occurs in the spring/summer, with slowdowns usually occurring in the winter. For many reptiles, these periods relate to periods of greater and lesser food abundance in the wild, as well as to pre- and post-breeding seasons when the animals would typically feed heavily.

What goes into making a healthy reptile? Just buying one isn't enough. (Just thinking you can buy one a problem: most reptiles sold in the pet trade and at too many expos and swaps are anything but healthy...). The many factors that must be dealt with include:

  • Enclosure of the proper size and orientation (vertical height for arboreals; width and depth to enable proper thermoregulation, wide-ranging species, and multiple inhabitants).

  • Sufficient humidity.
  • Water offered in a manner that can be utilized by the reptile.
  • Suitable and safe substrate (depth, type).
  • Furnishings (logs, rocks, hide boxes, according to species needs).
  • Proper heating and thermal gradients.
  • Proper lighting (day/night cycles, UVA/B when required).
  • Healthy food appropriate for the species, of the size that is appropriate for the individual.
  • Proper cleaning and disinfecting of enclosure, substrate, and furnishings.
  • Regular monitoring of enclosure and equipment to ensure proper maintenance.
  • Regular monitoring of the reptiles to detect early signs of stress or ill health.
  • Access as needed to an experienced reptile veterinarian for initial examination of new reptiles and exams and treatment as needed as problems arise.

Reading over this list it becomes apparent that unless one knows what the species' requirements are for the animals one has, one is going to have some problem meeting some or most of these requirements. If you don't know what a reptile needs to be maintained properly in captivity, it is going to be difficult to ensure you are providing a proper environment for it. If you don't know how a species should behave, you may miss the early signs of stress or illness, and thus not realize that something is wrong until the animal is very ill.

Even very small things that are wrong or just slightly off can, over time, lead to big health problems. Stress onset can be sudden and acute (an earthquake topples an enclosure; the owner moves or gives the animal away; the power goes out for three days; a new cage mate is introduced; the new family dog spends its time slavering in front of the enclosure; etc.) or it can be slow and insidious (reptile not drinking enough because the water bowl is too difficult to access; the crickets fed are just a little too large; there is no day/night cycle of temperatures in the enclosure; temperature gradients are not broad enough; temperatures are too hot or too cool; insufficient or improper hiding places provided; domineering cagemates; etc.). Sudden onsets bring about immediate and dramatic changes in color and behavior that even the only moderately observant owner can pick up on. Slow, constant stress, however, may result in slow, gradual changes in behavior and color. Behaviors such as thermoregulating, hiding, prolonged soaking, reduced appetite, irregular defecation, attitude, regression/increase in tameness, and more can all indicate signs of stress and illness.


What to look for
Assessing stress and illness in reptiles means looking at the animal itself as well as its immediate environment (enclosure and equipment) and the macroenvironment (the room in which the enclosure resides).

Check the overall appearance of the reptiles:

  • Are there any lateral folds, or are the folds normal for the species exaggerated in appearance or are there more of them?
  • Has there been a change in color?
  • Is the color of the skin dulling, darkening?

Check for changes in feeding habits:

  • Has food intake dropped off?
  • Food choices changed?
  • Are they selecting foods with higher moisture content?
  • Eating more?

Look for changes in the appearance, consistency and amount of feces and urates:

  • Is there less urates?
  • Is it thicker, more viscous?
  • Are fecal masses smaller, harder, drier?
  • Defecating less often?

Check for any changes in behavior:

  • Is the reptile lethargic?
  • Spending more time in hiding or in the cooler end of the thermal gradient?
  • Spends more time in basking area?
  • Prolonged soaking in water bowl?
  • More active, especially at odd times?
  • Engaging in frequent or prolonged digging, scratching or head-banging behavior?
  • Increased or decreased tongue-flicking when handled or enclosure is opened?
  • Has the usually tame reptile become aggressive (not associated with breeding season)?*

Check for changes in shedding:

  • Has the shed schedule become erratic?
  • If the reptile should be shedding in one piece (all snakes, some lizards), is it?
  • Are sheds taking much longer than usual to complete?

Check for physical signs of illness an injury:

  • Is it gaping (sitting with open mouth) for long periods of time?
  • Increased or thickened saliva?
  • Paling of the tissues inside the mouth?
  • Prolonged eversion of hemipenes or cloacal tissue after defecation?
  • Limping?
  • Swelling of digit, tail, limb, back, jaw?
  • Loss of muscle tone/strength?
  • Tremors?
  • Shakiness?
  • Less climbing or failure to climb?
  • Difficulty raising body off ground (for legged species)?
  • Difficult or failure to right itself?
  • Any lumps, bumps or bruised areas?
  • Any scabs?
  • Blisters?

If any of these signs occur, the environmental requirements of the species must be checked against the conditions actually occurring in the enclosure and any inadequacies or failures corrected.

If the proper physical environment is well established, the social environment needs to be looked at in enclosures where more than one animal is housed together. It should be noted that aggression and dominance behavior is not always overtly physical - there need not be any actual fighting. Subtle behaviors on the part of the dominant animal may result in a subordinate animal staying away from basking areas and food, slowly dying of stress-enhanced hypothermia and starvation.

If the physical and social environments inside the enclosure are not a problem, then the macroenvironment must be evaluated. Has the placement of the enclosure been changed (to a different room or different part of the original room)? Are children or pets annoying or scaring the reptile (think food chain/predator-prey relationships here as well as the annoyance factor of children)? Have you moved your household? Had to evacuate due to a natural disaster? Had the in-laws over for the week, totally disrupting your usual animal maintenance (and playtime) schedule? Been gone on vacation? These are all things that may seem like they wouldn't intrude on the life of our captive reptiles but, for many of them (especially iguanas and other social lizards), most definitely do.

There are also the things that go on behind your back... One woman found out from neighbor, who observed what was going on through the window while the owner was at work, that her cat would sit staring into her iguana's enclosure, nose pressed up against the glass, for hours at a time when the owner was at work. Since the cat never engaged in this behavior when the owner was home, she never thought there was a problem with the cat. Another woman found out that her husband was turning off the heating equipment in her reptile's enclosure at night after she went to bed "to save money - it's a cold-blooded animal, so it doesn't need heat all the time" was his rationale when she finally figured out why her reptile was sick and stressed. So, just because you are not directly observing something going on doesn't mean that something isn't happening to result in fear and stress in your reptile. You may need to become a sort of detective in carefully and deeply assessing everything that goes on in and around your reptile's enclosure as well as exploring as much as you can of the animal's natural history before you will be able to figure out what isn't right.

Please note that if your conditions have not been set up appropriately before reading this material, the shedding, defecation, and growth patterns you have come to expect from your reptile may in fact be abnormal. Reptile owners who have no previous experience with healthy reptiles believe that since their reptile is alive, eating, and defecating, that they are healthy. One 4-H reptile program leader informed me, for example, that ball pythons never shed in one piece. Her snake was covered in patches of unshed skin representing 3-4 different sheds, its eyes deeply dented from retained eye caps. Her snake was not healthy, but she insisted that, since that was the way her snake had always been, and that since it was alive and moving around, that it was "normal" for the species! I frequently encounter iguana owners who tell me that their iguanas defecate only once or twice a week even though they are eating daily. This tells me right away that their temperatures are too low. Once they are raised to the proper levels, the owners are often dismayed to find that, not only does the iguana increase its food intake, but its digestion speeds up to the proper rate, resulting in often copious defecation one or more times a day, depending upon the season. Most of these owners also find that their iguana isn't really as tame as they thought it was.


Common Feeding Problems
Failure of a reptile to feed may be due to one or more of several possible reasons. To get the reptile to start eating, the underlying cause for the failure to feed must be identified and corrected: failure to feed is a symptom, a sign of an underlying condition. Simply forcing feeding an animal will not correct the problem situation; it will just give the animal energy to survive, not thrive. Reasons for not eating include:


  • Still acclimating to captivity/new surroundings.
  • Water or air temperatures too hot or too cold.
  • Inappropriately sized or outfitted environment.
  • Improper lighting/photoperiods.
  • Enclosure too small for successful "hunting."
  • Water too shallow for aquatic reptiles.
  • Inadequate access to proper basking temperatures.
  • Inadequate levels of or exposure to UVA.
  • Dim lighting or low CRI for diurnal species.
  • Inadequate or missing hiding places.

Feeding Practices:

  • Fed at wrong time of day or night.
  • Not hungry due to being fed too often or too much at one meal.
  • Prey not thoroughly defrosted and warmed.
  • Prey not recognized as such.


  • Dehydrated due to inadequate or inappropriately offered water source, illness, or extensive use of nephrotoxic antibiotics.
  • Emaciated from chronic starvation.
  • Sick or injured.
  • Constipation (due to dehydration, lack of exercise, or impaction).
  • Impaction of foreign object.
  • Heavily parasitized.


  • Stressful surroundings (high traffic area, loud or shrill noises, presence of animals perceived to be predators, etc.)
  • Aggressive or dominant conspecifics scaring reptile away from food or basking areas.
  • Unable to compete successfully with cagemates for food.


  • Neonate not yet ready to eat.
  • Getting ready to shed.
  • Gravid or getting ready to breed.

If possible, it is always best to get the reptile to start self-feeding rather than resort to long-term forcing feeding or tube feeding. Once you have assured that the reptile is healthy and in a properly established environment, certain tricks may be employed if the reptile is still not self-feeding:


  • Feed live, then stunned prey, leading into feeding fresh killed, then prekilled prey.
  • Warm up bird or rodent prey (sealed in a plastic bag and submerged in hot water for 10 minutes, or heated under lamp or in oven to 180º F) for heat-sensing species and to increase the smell of the prey.
  • Take into account the species natural hunting and feeding strategies (actively seek and stalk vs. sit and wait) and offer food accordingly by manually manipulating it.
  • Scent rodent prey with appropriate mammal, reptile or amphibian species.
  • For snakes scared of live prey, lay killed prey in their enclosure, on their hide box, or even on their coils.
  • Gently "harass" the reptile by lightly tapping it on the nose or side of the mouth with the prey as you hold it with forceps or tongs.
  • "Shotgun" smaller prey items: once the reptile has started eating a small prey or scented prey item, hold another small or unscented prey item up to the back end of the prey being consumed. In this way, the reptile will have not choice but to start eating the second prey as the first prey is pulled back into its throat. Shotgun as many as are needed to constitute an appropriately sized meal (5-6 one- to two-day old pinks, for example, equal one fuzzy).


  • Prepare food in smaller pieces.
  • Mix in foods known to be favorites.
  • If a slurry was used (such as Ensure for herbivores, Hill's a/d for omnivores), add some of the slurry to the vegetable salad.


Changes in Temperatures and Humidity
The humidity and temperatures in an enclosure will vary through the year as the ambient room air temperatures and humidity rise and fall.

You may need to boost the humidity artificially more during the winter and winter months than during the Fall, for example. Hygrometers can be used to measure humidity and may be used as a guide to alert you when you need to boost the humidity or back off. Unfortunately, more is known about the temperature requirements of species kept in captivity than is known about their humidity needs. In the absence of specific humidity data, you will have to learn how to judge the adequacy of humidity based on the above points.

During the the winter, the fall in outside temperatures results in a lowering of the temperatures inside our homes. This drop in ambient room air temperature often results in a lowering of the temperatures inside the reptile enclosures. Always monitor the temperatures with several thermometers placed inside the enclosure. You may find that during the colder months you many not only have to boost humidity inside the room or enclosure, but you may have to add stronger or additional heating equipment just to be able to maintain the proper temperatures. One final factor that must be mentioned is the human tendency to demand that animals share the human's time schedule. Many people work during the day, coming home tired at night, often with an hour or more of chores to be done before they can settle down to relax. At that time, they may want to feed their reptile, or take it out for some together time. The problem is that if their reptile is a diurnal (active during the day) species, it needs to sleep at night. Constant disruption of the sleep cycle, as well as being forced to eat at night rather than during the day, results in long term low levels of stress. The same is true for people who work or otherwise stay up all night and sleep throughout most of the day. While this life style may be okay for nocturnal reptiles (other than the fact that nocturnal species do still require darkness at night to function normally), it is stressful for the diurnal and even for many crepuscular species. When we keep animals, we must accommodate their needs; they should not be forced to accommodate our schedules.

So, what does all of this have to do with my reptile's health?
Stresses, little and big, as well as the direct effects of environmental problems (cage size, orientation, heating, lighting, feeding, humidity, etc.) can lead to illness. Thermal burns, dysregulated endocrine system, sleep deprivation, constant fear and/or insecurity, malnutrition, etc., lead to numerous illnesses and disorders. Stress itself can suppress immune function, making the body unable to naturally fight off infection or keep internal parasites under control. The more stress, or the longer that it is allowed to continue, the weaker the animal becomes and the less tolerant it is to continued stresses and other problems in its environment.

Reptiles take a long time to die. Because of their ectothermy, their cold-bloodedness, they are able to conserve energy to maintain basic body functions for a long time, long after a mammal or bird would have succumbed or have deteriorated to the point where the owner would notice. Reptiles do not die "suddenly." When someone says that, what has happened is that their reptile was sick for a long period of time but, according to the nature of wild animals (which, after all, most reptiles still are, even if they were captive bred), they hid their distress: in the wild, it is the sick and the weak who are preyed upon. Those animals most adept at suppressing signs of ill-health or injury are those that will have a chance to recover before being eaten. In the wild as in captivity, reduced activity and increased hiding are behaviors associated with attempts at conserving energy (the less one moves, the fewer calories burned, a common reaction to slow starvation and to giving the body more calories to put into healing, for example) and trying to hide to avoid predation when the animal is too weak (or too cold) to effectively defend itself.


Behavioral Changes
Changes in behavior can be a sign of an underlying physical problem. We tend to think of health problems as causing lethargy and loss of appetite, but animals may also become snappy, cranky, and may react abnormally to accustomed interaction and stimuli. Some iguanas may get aggressive. When the aggression occurs in green iguanas, known for their breeding season and territorial aggression, such behavioral changes are often dismissed as "just" being related to "typical" male aggression. As an increasing number of iguana keepers are finding, abnormal aggression may also caused by huge bladder stones, tumors, abscessed organs, and other as yet undefined, pain, disorders and pathologies. When investigating the possible causes of abnormally aggressive behavior, do not discount a primary physiological cause until you and your vet have thoroughly checked it out.

Suggested Readings:

Barnard, Susan M. 1996. Reptile Keeper's Handbook. Krieger Publishing Company, Malabar FL, 252 p.

Benyon, Peter H., Lawton, Martin P.C., Cooper, John E. 1992. Manual of Reptiles. Iowa State University, Ames IA, 228 p.

Duncan, I. J. H. (1992). Behavioral assessment of welfare. In J. A. Mench, S. J. Mayer, & L. Krulisch (Eds.), The Well-being of Agricultural Animals in Biomedical and Agricultural Research. (pp. 62-68). Bethesda MD: Scientists Center for Animal Welfare.

Duncan, I. J. H. (1993). The science of animal well-being. Animal Welfare Information Center Newsletter, 4(1), 1-4-7.

Kreger, M. D. (1993). The psychological well-being of reptiles. Humane Innovations and Alternatives, 519-523.

Lance, V. A. (1992). Evaluating pain and stress in reptiles. In D. O. Schaeffer, K. M. Klienow, & L. Krulisch (Eds.), The Care and Use of Amphibians, Reptiles and Fish in Research. (Pp. 101-106). Bethesda MD: Scientists Center for Animal Welfare.

Laule, G. (1993). The use of behavioral management techniques to reduce or eliminate abnormal behavior. Animal Welfare Information Center Newsletter, 4, 1-2, 8-11.

Mader, Douglas M. (1996) Reptile Medicine and Surgery. W.B. Saunders Company, Philadelphia, PA. 512 p.

Moberg, G. P. (1985). Biological response to stress: Key to assessment of animal well-being? In G. Moberg (Ed.), Stress in Animals. (Pp. 27-51). Bethesda, Maryland: American Physiological Society.

Society for the Study of Reptiles and Amphibians. 1994. Captive management and conservation of amphibians and reptiles. James B. Murphy, Kraig Adler, Joseph T. Collins, editors. SSAR, Hays, KS, 408 p.

Warwick, C. (1990). Reptilian ethology in captivity: Observations of some problems and an evaluation of their aetiology. Appl Anim Behav Sci, 26, 1-13.

Warwick, C. (1990). Important ethological and other considerations of the study and maintenance of reptiles in captivity. Applied Animal Behaviour Science, 27(4), 363-366.

Warwick, C. (1991). Observations on disease-associated preferred body temperatures in reptiles. Applied animal behavior science, 28(4), 375-380.

Warwick, C., Frye, F.L., and Murphy, J.B. (1995). Health and welfare of captive reptiles. Chapman & Hall, London. 299 p.

Zug, G. R. (1993). Herpetology: An introductory biology of amphibians and reptiles. Academic Press, New York. 527 p.


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