Obesity is a common problem in many reptiles and amphibians kept in captivity. Many species are overfed because of owners ignorance of natural feeding intervals and of food types commonly eaten in the wild. For example, feeding meat to tortoises and green iguanas, both of which will eat meat if offered it although wouldn't necessarily eat meat in the wild. The feeding of meat to such species can result in many issues including gout from the excess protein, soft tissue mineralisation from excesses of calcium and vitamin D3 and fatty liver syndrome (hepaticlipidopsis) from the intake of excessive fats, which is when the liver cells are filled with fat deposits impeding their function. Snakes also suffer from these conditions when fed overly fat rodents or simply fed too often. Physical signs of obesity in snakes is the appearance of prominent 'hips' at the base of the tail. The aim should be a reptile that does not look emaciated but lean.

Although not a disease, it is still a serious issue amongst captive reptiles. Activity should be encourage by means of handling or an enclosure design which encourages natural activity e.g. branches, vines or rocks to climb. Burrowing species should be given suitable substrate to exhibit natural behaviour and burn off energy. Enclosures should be large enough for the animal to move around with ease, movement should not be overly limited.

Obesity is a particular problem in species with a "sit and wait" strategy as there is no need to exercise to obtain food. In such circumstances enclosure design is very important to allow sufficient energy expenditure.


Anorexia is probably one of the most common issues faced by reptile owners. The reason for an anorexic period may be due to normal physiological changes (e.g. just before shedding, egg laying or hibernation, brumation, etc.). or related to improper management, such as poor nutrition, inappropriate temperature, humidity and/or substrate, stress caused by cage mates or owner, or due to both infectious and non-infectious diseases. Owners should assess the living conditions of their animal to determine if the cause may be due to poor management, if no fault in husbandry is found the cause may be down to physiological changes or disease, if in doubt take the animal to a vet. As a general rule, a reptile going through a normal physiological phase of anorexia should not lose more than 10 percent of their body weight. To monitor this accurately, it is good husbandry practice to weigh the individual animal on a routine basis (e.g. once a month for healthy animals or daily for animals of concern).

Reason for Refusal to Eat

Inappropriate Environment

Poor environmental conditions such as incorrect heating, lighting, humidity and substrate can all be contributors to the development of anorexia. Environmental temperature can effect nutritional uptake because reptiles and amphibians are ectothermic, that is to say they rely on their surroundings to maintain their body temperature. There is an preferred optimum temperature zone (POTZ) that will allow their enzymes and metabolic pathways to function at their optimum levels, so environmental temperature will influence the rate of digestion of the food offered. If reptiles are kept at temperatures lower than their POTZ than digestion may not occur before the prey item becomes rancid inside the animal. Similarly if kept at too high temperatures the reptile may not be stimulated to eat at all and dehydration and heat stress may set in. Incorrect humidity may cause the onset of skin or respiratory disorders which would also result in diminished appetite. Lighting is important for providing day/ night cycles so the animal may know whether it's daytime or night-time and what season it is by the day length. Many reptiles rely on light cycles to determine when to breed, hibernate and perform other seasonally determined physiological processes. Anorexia may result from stress from an inability to determine the correct season or time of day and therefore are unable to respond appropriately. Incorrect UV lighting would further induce a deficiency of vitamin D causing the animal to become anorectic through illness. Ingestion of substrate may also be a cause of anorexia if large quantities of substrate were consumed, either intentionally or accidentally, causing impaction and risk of internal rupturing.

Inappropriate Food Item/Feeding Method

The type of feed given and method in which it's presented may be a cause for refusal, for instance, wild caught snakes have been known to refuse white lab rats but would strike at brown rats. Some animals such as snakes may see one type of animal as a food source, for example some snakes which are raised on mice will refuse to eat rats, and snakes which are fed live prey may refuse frozen thawed. In such cases introducing different food items to a non feeding animal may be a solution. It is a good idea to enquire about the animals feeding history before purchasing. Food items must be appropriate to the species it's being fed to, food which is too big may not be accepted by the animal. Some lizards have been known to 'go off' a certain food item if given a varied diet and may simply have a preference over what it's being fed. For example, in the past my geckos have refused crickets but readily ate locusts and mealworms.

It is best to feed animals during their most active periods, nocturnal species such as leopard geckos or corn snakes naturally hunt during the night or twilight hours so may accept food more readily at these times. Some species are shy feeders and prefer to eat alone, hidden away from sight.

Live food should be removed if not eaten, crickets left in with lizards have been known to cause skin damage by insect bites. Pre-killed vertebrate prey is strongly recommended to prevent potential suffering of both prey and predator species.

Stress and Social Competition

Stress may be caused by limited space and lack of hides which lead to "maladaptive syndrome”. That is to say an animal which has adapted poorly to the environment it's been given. If not provided with sufficient hides, the animal may feel over-exposed so will become stressed and refuse food. Another cause of stress may be over-handling of shy species (e.g. Royal Python and Chameleon) or overcrowding causing stress through bullying and competition.

New animals are usually very stressed after a move and may need time to adapt to their new surroundings first before they are ready to eat. There should be some concern if the new pet has not eaten in the first week and a change in management may be required, perhaps the animal feels too exposed or is being disturbed too much. Wild caught animals often refuse to eat as they endure a great deal of stress during capture and captivity. Some species, such as the royal python are predisposed to short periods of anorexia but Captive Bred royals do not have the same feeding issues to the same extent as wild caught individuals.

Illness or Physiological Changes

Anorexia may be a sign that your animal is suffering from some form of disease or disorder. It may also be caused in response to normal physiological changes such as shedding, preparing to hibernate or in preparation of the breeding season. During the shedding process many animals will refuse to eat during this time. Females may also refuse if they are ovulating, even if they have not been bred they are still capable of producing eggs. A suitable place to lay must be provided, even for unbred females to prevent egg binding (when the eggs become stuck inside the animal). Post Hibernation Anorexia (PHA) as observed in chelonians can be an issue in those not prepared appropriately before hibernation or not properly cared for after waking from hibernation.

PHA is a condition seen in mediterranean species of tortoise which hibernate during winter months. Those affected by PHA often display signs of systemic or respiratory tract infections (such as runny nose syndrome) and low body weight in relation to length (Jacksons ratio). Dehydration is also apparent in such cases, treatment requires aggressive fluid therapy and nutritional support by a vet. Causes may be due to disease during or before hibernation, poor nutrition leading to poor fat reserves before hibernation, owners failure to observe recovery from hibernation for several days so no food has been offered at the critical time or exposure to cold whether immediately after recovery. To prevent PHA it is important to attend to the disease before hibernation and those too ill or underweight should not be hibernated at all. Tortoises should be checked regularly throughout hibernation, at least once or twice a week so if the tortoise does come out of hibernation early, food and water may be provided immediately. Bathing the tortoise immediately after waking in warm water and cleaning the nose, eyes and mouth can help stimulate appetite. Tortoises which have recovered from hibernation, even if they have awoken early should not be re-hibernated the same winter.

Re-feeding Syndrome

If anorexia in a reptile has persisted for some time it is essential that the animal is rehydrated before attempting to feed. Initial feeding after this should be started off at very low levels. This is because excess calories and proteins cause rapid uptake of glucose from the bloodstream into the cells, which takes potassium and phosphorus with it. This can lead to life threatening hypokalaemia and hypophataemia.

Encouraging Feeding in Snakes

As a general guide to feeding reptiles it is important to note that it is illegal to feed live vertebrate prey to another animal in the UK without veterinary permission. It is also not recommended for ethical and safety purposes. All rodent prey fed to snakes and lizards must therefore have been humanely killed first. Some exceptions however include animals which will not feed on pre-killed prey and require live feeds to survive. Any live feeds must be carried out by an experienced individual and only done as a last resort. Live prey may damage the reptile if the latter is not hungry and does not kill the prey quickly. Furthermore, live prey carry the risk of disease, any threat of disease is eliminated during the freezing process. To encourage anorectic snakes to eat, a number of tricks may be employed including:

* Warming prey briefly before offering

* Breaking prey open to release the scent of blood - (e.g. 'braining')

* Teasing the snake by moving the dead prey item around the cage with forceps to mimic live prey

* Trying a variety of colours of prey – some snakes will only take dark furred rodents

* Scenting by wiping scent of a different prey item (prey item may not smell strong enough - as is the case with pinkies)

* Transfer the skin of one prey item over another (e.g. skin of a chick over a mouse - 'jacketing')

* Ensure there are plenty of areas to hide – some snakes like to consume prey in a box or hide

* Leave prey in overnight – some species prefer to hunt at night in privacy

* Choose the next smallest size of rodent

NB Term ‘pinkies’ refers to nude neonatal rat or mice pups, ‘fuzzies’ refer to week old rat and mice pups with a thick covering of fur and ‘furries’ refers to juvenile rat and mice pups between 1-3 weeks of age which have soft but longer covering of fur.

Assisted and Gavage Feeding

If all other attempts to feed the animal fail then as a last resort assisted feeding may be considered. Assisted feeding of lizards may be achieved by blending its food into a 'soup' like mixture and feeding the animal via a syringe. The animal may lap the mixture directly from the syringe or the mixture may be slowly introduced directly into the mouth. Force feeding with snakes requires pushing whole prey into the mouth of the snake and carefully down the throat, then massaging part way down the oesophagus. Unfortunately assisted feeding quite often results in regurgitation from a snake that's persistently unwilling to eat.

Excessive stress from force feeding can be dangerous causing more harm than good, because of the stressfulness of the process I'd recommend gavage feeding to such a debilitated animal. Gavaging involves inserting a sufficiently lubricated feeding tube down the animals oesophagus and syringing liquid medications or nutritional formulas directly into the stomach, or partway down the oesophagus, this is less stressful than force feeding whole prey as it is both quicker and safer. It is recommended that you discuss this process with your vet, they will provide you with the equipment and a demonstration on the process as well as specific requirements for your reptile (e.g. Emeraid Carnivore (a nutritional formula for debilitated and sick carnivorous animals) is fed 1/2% of body weight on day 1, 1% on day 2 and 2% on day 3 and there after - so amount fed is relative to body weight). The main danger with gavage feeding is accidentally putting the tube down the wind pipe instead of the oesophagus. This however, is difficult to do with snakes as the wind pipe is located at the very front of the mouth and usually closes when the mouth is open. Double check your placement of the tube before you begin syringing to make sure. Young animals in particular require support as they lack the reserves of a mature animal so cannot go as long without eating.

If the animal is dehydrated (as evidenced by loose skin) then it may require hydrating first (provide moist hide, water with reptoboost, possibly even baths). Make sure the animal is in a calm quite area to reduce stress as much as possible; plenty of hiding spots and coverage, is infrequently disturbed and only handled when necessary. Also make sure the temperatures are warm enough and if you have a lamp, put the basking spot up to a max of 35C, this can sometimes encourage a feeding response.

With gavage feeding, the solution won't be so filling that the animal won't accept food if it's starting to recover, so you may occasionally offer for and the animal may choose to accept if it's sufficiently recovered.

Nutritional Supplements for Ill Reptiles

There are two main nutritional supplements for ill and recovering animals that are commonly recommended by vets: Reptoboost - a probiotic containing live cultures to encourage healthy gut flora, as well as vitamins and electrolytes to support dehydrated animals; and Critical Care Formula; A mix of proteins and amino acids to provide energy and prevent muscle catabolism (the breaking down of muscle tissue for energy). Neither of these supplements supply the animal with its necessary intake of calories so emerald or similar is required alongside these two other supplements for supporting chronically anorexic or ill reptiles.

Reptoboost is highly palatable and can be offered in the reptiles drinking water at a ratio of 1 scoop per 500ml of water, this is also true of critical care which can be given at a rate of 1 scoop per 200ml of water, or 1 scoop per 1kg of animal per day for greater needs. Animals may also be bathed in the solution as some fluid will be absorbed via the vent, benefiting the animal even if the animal does not directly drink. After bathing the animal should be rinsed with clean water to remove any residue and prevent any possible encouragement of infection. In serious cases the supplements can be administered via feeding tube.