Stress in Reptiles.

I recently began wondering about how you discern stress in reptiles. What is stress and how can it be avoided? How commonly are animals maintained in stressful environments in captivity and what sort of threats do such stresses create? Upon researching the subject I found a plethora of interesting information. This article aims to get the reader to think about stress and stressors in reptiles in relation to their own animals - Have you done all you can to provide a happy home for your pet? Have you even thought about it since you first purchased your reptile, or have you just relied on the information you received at the point of sale?  This article is not necessarily designed for the already experienced and successful keeper but for those of you who may have still to put any real thought into stress processes and alleviation or are totally new to the hobby.

Never before has the market seen so much competition with the diversity of species available and the amount of private breeders producing surplus stock peaking. Reptile stores literally seem to be popping up everywhere and what were just general pet stores last week now claiming to offer ‘professional’ reptile solutions.

Owning and running a reptile shop on a day to day basis, not only allows me to provide reptile solutions and advice for my clients, but I am also visited frequently by people with reptiles which we not purchased from myself for advice and to assess the well being of their reptiles when they feel there is something wrong. Over time I have seen the proportion of poorly advised and inadequately researched keepers more than double, which is puzzling since information available on herpetology and the various lines of reptile care has never been more readily available in the modern age of the internet. I am not a vet and have no formal medical training, but caring for reptiles for over 15 years has allowed me to become experienced in reptile welfare. Time after time I have seen cases where I believe an animals poor health is as a result of stress.

A normal healthy animals body maintains its delicate internal balance, or ‘homeostasis’ by adjusting to its external environment. However, if this environment becomes adverse or abnormal, the animals system becomes stressed, resulting in a cascade of effects, sometimes leading to detrimental health. A stressor is therefore an external force applied to animals that threaten the usual status quo.

Initially it is important to understand that a true picture of stress is difficult to ascertain in reptiles. Simply capturing or studying a reptile causes the animal to produce a stress response. Reptiles are seasonal by natural habits and dependant upon the time of year (i.e. hibernation) and immune response may differ within a single specimen. It is therefore impossible to create a situation in captive husbandry where a reptile becomes entirely stable and fluctuations in reptile function and responses may be entirely natural.

Having said that, reptiles are incredibly sensitive to change and such change elicits itself as stress. Stress can be categorised using a variety of ideologies. However, having extensively read around the subject, I have found that Selye’s three point system of stress, termed the ‘General Adaptation Syndrome’, most concisely describes the most salient causes and ailments of stress:

1.                   Alarm – An acute stress response seen within hours of introduction. Homeostasis resumed once the stress source is removed (an example of this being captured in a bag). Symptoms medically found to occur (though not present to the eye) are involvement of the thymus and lymph nodes, ulcers developing in the digestive system and stimulation of the adrenal gland.

2.                   Resistance – If a stress source remains present or becomes chronic in certain cases the animals body accepts this and homeostasis is eventually resumed. This is not before a non-defined period of cessation of growth and reproductive function has taken place. Bear in mind the animal can ‘resist’ a stressor but each resistance is specific to one stress source. With each new stress a new resistance must be achieved. The period in which an animal can mount a resistance to a stressor may be related to the body temperature or time of season that the stress has taken place.

3.                   Exhaustion – If the stress is severe and consistent the return of the symptoms from the alarm stage become present. If the keeper fails to remove or even notice the stress of the animals at this stage death will usually occur shortly after. Later in the article we will look at what stressors may be commonly present in a reptiles’ environment and how to deal with them from a husbandry related perspective.

Knowing that stress exists in reptiles and understanding the stressors that lead to such stress, however if pointless if we cannot tell when are reptiles are actually stressed and therefore cannot begin to remove such stressors. – How do we know our pets are being subjected to stress? There are several indicators that a reptile is enduring stress, as seen in their response to differing environmental conditions. These responses will now be discussed.

Responses of reptiles to environmental or abiotic stressors

• A key response of reptiles to stress is the increased activity of the adrenal gland (responsible for the secretion of corticosteroids – the proverbial yard stick upon which stress is measured in reptiles) and decreased activity of the sexual organs (reduced reproductive potential). Plasma corticosteroids concentrations are used to measure the relative stress that an animal may be under. Factors affecting these concentrations include age, sex, nutritional state, social state, stressor type and frequency of exposure. Corticosteroids & sexual hormones appear to regulate the immune system of reptiles and Stress has proven to affect most steroids involved with immunity.

• A healthy animal’s body is generally in a state of anabolism. This is a period of growth, storage of fat and reproductive reception/ability. An animal’s body living under stressed conditions is generally in a state of catabolism. This is a destructive metabolic process in which growth is stalled and a reduction in fat stores and muscle integrity is seen. Reproductive activity/receptivity is also ceased.

Reducing Stress

Knowing an animal is stressed and knowing how to overcome such stresses are two entirely different scenarios. I merely have used the above information to look at my own captive care techniques and hypothesized about what if anything needed to be changed to ensure the animals were under the least amount of stress in order to promote the sale and raising of healthy animals.

The first thing to consider when considering the captive husbandry of reptiles is what exactly is the keeper responsible for? The simple answer is everything. Due to the cold-blooded nature of our charges we are totally responsible for their environmental, social, reproductive and nutritional needs. Each of these needs then has multiple sections, which can, if not thought about properly, constitute a stressor and then put the health of your animal at risk. This is why research of a reptile prior to purchase is so important. The purchase of general non-venomous reptiles by the public is not licensed and therefore what obligations apart from to provide stock and equipment is a shop under? None - hence why problem reptiles and keepers find their way in to mine and every other respectable reptile shop.

Considerations when purchasing a Reptile

All of the suggestions are open to conjecture. People have been keeping and breeding reptiles for far longer than I have. I simply believe that by taking the time to look at factors that have been proven to cause animals stress must be a worthwhile project.

• Correct enclosure size for inhabitant: Consider whether the tank that has been provided is too large or too small. Young snakes such as hatchling Corn Snakes (Pantherophis Guttatus) should not be housed in adult size tanks from birth. From experience I have learned that through what can only be termed as fear young captive snakes moved from the small secure baby racks of shops to vast open vivaria rarely adjust well. Refusal to feed, additional or uncharacteristic aggression and general inactivity are common factors. Security may well be the issue. Not the security of the cage as a lock but the mental security of the captive. Provision of multiple hides placed along the thermal gradient to maximise the possibility of ‘safe’ thermoregulation may help the settling in process. This does seem to be a problem common in baby snakes and not so severe in young lizards, although that said I have noticed similar behaviour in Leopard Geckos (Eublepharis Macularius). Researching a species before purchase provides information as to commonly accepted sizes of enclosures. A trip to a local reptile shop/s to see what information is available at a face-to-face level is also useful. If such information from your local shop is not forthcoming there are a multitude of reptile related forums online where members will willingly help as best they can. Opinions can differ so use common sense to read between the lines.

• Psychological security for inhabitant: Briefly mentioned above, the provision of adequate hides for the species in your care along the thermal gradient will encourage correct thermoregulation without exposing possibly high-strung species to stress. Considerations about the type of hides are important. Animals usually located in burrows in the wild should be provided with subterranean hides buried under the cage substrate. By encouraging natural activity possible stressors could be avoided. A species, which made regular use of such hides in my care, were Curly Tail Lizards (genus: Leiocephalus). Leiocephalus are found on rocky escarpments, open forest and on beaches (Kaplan), the provisions of some securely glued rocks providing multiple hides could have worked as well or better. The thing to grasp is there is not just one solution; you have options but options only present themselves once you have researched on the species to give you your parameters for care. Sand swimming species placed on loose substrate make the substrate their hide making the whole subject far less rigid. Even though hides were provided for Sand Fish Skinks (Scincus scincus) they were rarely used if ever, choosing instead to retreat into the substrate in the blink of an eye whenever a watchful human eye approached. Berber Skinks (Novoeumeces Schneideri) employed similar tactics to the sand fish. Royal Pythons (Python regius), certainly of captive farmed (CF) or wild caught (WC) origin can be notoriously difficult to settle in for inexperienced keepers. Provision of multiple bark type hides which may be a tight fit for the snake seems to help.

• External Stress Considerations for the inhabitant: It may also be worth considering factors, which affect the stress levels of a captive reptile from outside the enclosure. Serious consideration of the position of the enclosure is important. This may seem strange but highly-strung species for example are not going to benefit from a high traffic area in the house (a landing or kitchen for example). Similarly, is the tank accessible by children who may tap or disturb the inhabitants thus resulting in stress responses? Thermo-regulatory factors can play an important part in the welfare of your Captive reptiles. Avoiding direct sunlight or positioning in the immediate vicinity of a radiator will keep temperatures under control (as long as a thermostat is used). Exposure to either of the above factors may render even a thermostat impotent. The opposite too this would be exposing an animal to temperatures, which are too cool. Where low air temperatures may be an issue (such as un-insulated garages, sheds, utility rooms etc) the gradient may fall from the basking area far too sharply (certainly for tropical animals). Do you have inquisitive pets such as cats or dogs, which may show an interest in a reptile’s activities? Could this induce a stress response linked to a fear of predation?

• Thermal gradient for inhabitant: Dependant upon the type of animal you wish to keep each species has its own thermal and seasonal requirements. These must be fully researched to ensure a healthy captive. Generally speaking there are three types of commonly seen biome types in captive reptiles.

Temperate: Mid range summer temperatures and a hibernation period (Corn Snake – Pantherophis Guttatus, European Green Lizard – Lacerta Viridis)

Tropical: Mid to high range temperatures through out the year (Boa Constrictor – Boa Constrictor Imperator, Green Iguana – Iguana Iguana)

Desert: Extreme daytime temperatures with marked cooling at night (Bearded Dragon – Pogona Vitticeps)

Animals maintained under correct temperatures at the basking site (this can only be achieved through thermostatic control) and enjoying the full recommended range of temperature for the species will display normal corticosteroid levels and immune system reactions will be quick to respond*. Temperature induced stress could possibly affect corticosteroids and sex hormones. A suppressed reaction from the immune system has been found to occur in certain lizard species, and this was linked to being kept at permanently lower temperatures. The immune systems delayed or weak response may allow the onset of illness, which could jeopardise your animal’s health if not altered. A commonly seen problem with constant cool temperatures is a respiratory infection. Simply raising the temperature is rarely enough and veterinary assistance in the form of antibiotics will be necessary. Being kept too hot can also have its down falls, dehydration and unnatural or forced aestivation may occur. Animals in this situation usually reside almost permanently at the cool end or in the water bowl if indeed one is provided. Your animal should readily move around all areas of the vivarium, if at any point you noticed prolonged periods (days) spent in one end in preference to the other one must assume there is a problem with the temperatures provided and indeed the gradient. It would be narrow minded however to think that reptiles are not naturally exposed to temperature changes and often to achieve breeding success these temperature variation must be recreated. Due to an imposed cooling period where immune systems suppression could be present it is imperative that you ensure you animal is in good health. If you have any doubts about the animals’ health prior to hibernation/brumation abort all plans to breed that year and maintain at standard temperature values.

*- Dependant upon the time of year.