The Reptile Patient
Sharon Redrobe BVetMed BSc MRCVS
Quality of Light
Nutrition and Feeding
This can only be a basic guide to reptile medicine and surgery due to the time allowed. For more information you are referred to the reference list. Only the most important/common conditions in lizards,
snakes and chelonians (not crocodilians) will be covered.
Environmental stress (inadequate husbandry) predisposes an animal to infection, by immunosuppression. Thus a knowledge of basic environmental requirements of the reptile patient is vital in the prevention and cure of many diseases.
Cage dimensions vary with species; arboreal species require height, terrestrial species floor area, aquatic species water and basking platform. Most reptiles are great escape artists, locks and secure lids are recommended. There is often a conflict between natural and clean, safe environment; real plants, bark chippings (microwaved), sand are more difficult to keep clean and can cause impactions. Items that can be ingested e.g. small stones, gravel, corn cob bedding, should be avoided. Newspaper is perhaps the best substrate as it is digestible, cheap and disposable. Other options include washable carpet squares, Astroturf. Certain species e.g. sand boas (Eryx spp.) must be given a burrowing substrate.
Cage furniture should be kept to a minimum. A few items of safe cage furniture include large stones, stable `caves' or hides, secured branches that can take the weight of the reptile, non toxic, non injurious plants. A body of water is required for aquatic and semi-aquatic species. Adequate filtration and heating should be provided. Care should be taken not to heat the water to the PBT in semi-aquatic species such a Red-eared terrapins; these animals will then `bask' in the water rather than basking on a dry area and drying the shell. This makes them prone to skin and shell diseases. The use of a separate `feeding tank' for these species prevents the soiling of the main vivarium with stale food. Water should always be available to all reptiles in a form that is acceptable to them e.g. chameleons will only lick droplets, tortoises need to immerse their mouth and nose and so should be placed in shallow water 3 times a week.
Reptiles are ectotherms i.e. regulate body temperature by behavioural means. preferred body temperature (PBT) = optimum temp for bodily functions ( movement, digestion, feeding, reproduction) reptiles require a range of temperatures to be able to thermoregulate (preferred optimum temperature zone/ POTZ). Sick reptiles seek out the high end of their PBT (`behavioural fever') Primary heat Source - for background/ ambient heat (at the low end of the POTZ). Use heat tapes, mats, or radiant heat from incandescent bulbs, ceramic lamps. Always provide a heat source that is not also a light source in order to provide the correct period of darkness whilst maintaining the vivarium temperature. Secondary heat source - specific areas can be provided with a higher temperature. For lizards, a 50 - 75W bulb directed downwards is generally adequate. For arboreal species this should be directed onto a branch, and onto a rock/ floor area for terrestrial species. Semi-aqautic species require a dry area with a basking light of 50 -75W. A heat pad is used to maintain ambient temperature. Placed over 1/3 side of the vivarium. Ultratherm heat mats generate ultra-infra- red heat and so may be taped to the side of the vivarium where the reptile can bask in the beam. Polystyrene should be fixed to the back of the heatpad, and under the base of a glass vivarium. hot spot overhead bulb (and UV supply if required). Prevent direct contact hot rocks NOT RECOMMENDED warm artificial rocks used to heat reptile by direct contact. Monitoring is important to
check range of temperatures. The ambient temp should not exceed the PBT, the temp under hot spot should not exceed the maximum tolerated. Maximum and minimum thermometers and thermostats are essential.
Timers are required for the maintenance of a stable photoperiod. Suitable photoperiods are given below:
|Tropical species||13h/11h light/dark||11h/13h light/dark|
|Temperate species||15h light ||9h light||12h light |
It should be obvious from the above that it is not suitable to have the ambient heat source as a light source, or the reptile will be stressed.
Quality of the Light
UVA (320-400nm) this range stimulates agonistic and reproductive behaviour in lizards UVB (290-320nm) this range is important for the conversion of provitamin D3 to previtamin D3 in the reptile skin, and so is important for calcium metabolism. Most proper reptile broad spectrum lights aim to mimic the light characteristics of the midday sun (having UVA and B, colour temperature of 5000-6500 oK, a colour
rendering index of >88, and infrared spectrum), e.g. Vitalites, Trulites. It is not known however, if this `midday sun' is the most beneficial, or even `natural' when maintained at around 12 hours per day.
UVB of suitable wavelength and strength is essential for maintaining the health of certain species e.g. the green iguana (Iguana iguana). Note; 20 hours under a reptile striplight is only equal to 5 minutes of sun at the equator. Triggers physiological processes e.g. breeding, hibernation fluorescent tubes are preferable to light bulbs, which also produce heat but no UVB. `Truelight' and `Durotest International (Vitalite)' produce a natural light spectrum. Black lights can be used to provide greater strength UVB. These lights are needed for only 15 minutes daily (care: causes human cataracts). Must be replaced every 6 months to ensure effectiveness. Access to unfiltered sunlight has been reported to precipitate aggression in pet iguanas.
Does this mean that artificial light sedates our captive iguanas? All reptiles should be given access to unfiltered sunlight where possible, as long as this does not place them outwith their POTZ.
50-70% tolerated by most species. It should be relatively low for desert species e.g. ground leopard gecko (Eublepharis macularis) at 20-30%. A humidity chamber should be provided for ecdysis (an ice-cream carton filled with damp tissue paper). A relatively high humidity is required for rainforest species e.g. emerald tree boa (Corallus caninus) and the green iguana , requiring 70-80%, and so daily spraying with tepid water is required. It has been suggested that the high incidence of bladder stones in captive iguanas may be because they are subclinically dehydrated as they are not often kept in a humid enough environment. The relative humidity of the enclosure can be increased by spraying the animal, plant or cage furniture, by including damp moss, peat or vermiculite in the vivarium. Humidity must NOT be increased by decreasing ventilation or ill health will result.
Nutrition and Feeding
Correct identification and age of the reptile concerned is essential in providing the proper diet. Some snakes naturally eat lizards when young, then mammals when the are older (e.g. sand boas), and so greater care and patience will be required when `training' them to eat the offered food in captivity. Snakes should be fed in isolation or cannibalism can result. A calcium : phosphorous ratio of 1.5 : 1 is essential, plus adequate vitamin D3 provision. Regular use of vitamin and mineral supplements; Nutrobal (Vetark to coat the food) is recommended in all those that do not eat whole vertebrate prey. It is ILLEGAL and INHUMANE to feed live vertebrate prey, even to an anorexic animal. Young captive-born snakes may require assisted feeding initially. Food may be bloodied, warmed and wiggled to encourage feeding. Live feeding is both stressful to the prey species and potentially dangerous to the predator species. Severe rat/ mouse bites can be inflicted on reptiles which are inept or just not hungry. Insectivores may be offered live invertebrates which should always be coated with a suitable reptile supplement (Nutrobal; Vetark). Ensure insects have been fed fruit, cereal and supplement for 24h first or will be nutritionally empty. This is called nutrient loading. Reptiles, especially youngsters, should not be overhandled when they have recently eaten as they may regurgitate. In general, do not handle for 48 hours after a feed. Aquatic species (which feed in water) e.g. red-eared terrapin (Trachymys scripta elegans) should be fed in a separate feeding tank to prevent water fouling. Commercial food should be supplemented with whole fish etc. Terrestrial chelonians are usually herbivorous, but may also eat dog food. Some snakes e.g. constrictors, prefer to eat in a small, dark box; pythons may require `teasing' with food. . For most species, the provision of a wide shallow dish for drinking water is sufficient. Tortoises should be placed in shallow water to drink at least weekly.
Selected Food Preferences for Common Pet Species
Such as: iguanas, spiny tailed lizards. Feed leafy green vegetables, some fruit, very little animal protein, and always a good reptile vitamin and mineral supplement (Nutrobal; Vetark). Feed daily.
Black and brown crickets are readily available. They require nutrient loading and dusting with vitamin and mineral powder. A variety of insects should be offered e.g. mealworms, waxworms, earthworms, grasshoppers, caterpillars, cockroaches etc. (NEVER maggots). Generally feed 2-3 times/week according to condition.
Prekilled rodents of appropriate size are best. Chick and fish can also be offered as appropriate to the species. Generally feed 2-3 times/week according to condition.
Box turtles. These are opportunistic carnivores. Food items include snails, beetles, slugs, worms, spiders, small mammals, birds. Also mushrooms, tomatoes, raspberries, dandelion leaves etc. Feed daily.
Tortoises. These should be fed 85% vegetables (mostly dark, leafy greens, grasses and weeds) with 10% fruits and less than 5% cereals, eggs (plus the shells). Feed daily.
Aquatic turtles/ terrapins. Feed a variety including mice of appropriate size, earthworms, slugs, fish. Feed some fish pellets, insects, dark leafy greens. Avoid feeding just raw meat as the Ca:P ratio is reversed and feeding too much of this item can lead to metabolic bone disease. Feed adults 1-3 times/weeks, more often for young.
Most of the commonly kept `pet' species can be fed rodents of appropriate size e.g. corn snakes, boa constrictor, royal python, pine snake. Garter snakes eat fish and amphibian from the water. If fresh fish are fed, supplementation with B vitamins is required to prevent severe deficiency problems resulting in `fitting' (cerebrocortical necrosis and loss of righting reflex).
Many reptiles appreciate a `hide' or darkened area to feed, especially Royal pythons.
Transport animals in an insulated, warm, dark, secure box or bag. Specific reptiles should be handled as follows:-
Hold shell slightly cranial to hindlimbs but caudal to forelimbs (like a hamburger!). this may lead to scratches from the struggling limbs. The animals may be restrained around the back of the shell between the hindlimbs (particularly in the more aggressive species which scratch and bite), although the hand may be covered in faeces!!. Take added care with the boxed terrapin (Terrapene spp) which can close its shell via a hinged plastron and trap fingers. Many aquatic species have a fierce bite and are aggressive.
Hold around the neck and pelvic girdle with one hand, and with the other around the pelvis and hindlimbs. A soft cloth may be used to catch the delicate skinned geckos. Never handle a lizard by the tail as some species shed them (autotomy) and the regrown tail is never the same shape and size as the original. Fractious larger lizards should be held with the hindlimbs restrained flat against the tail with one hand and the forelimbs against the thorax with the other hand to restrain the animal and to prevent the handler being scratched. Be aware that iguanas whip their tail in defence or aggression and can be very accurate and painful. Always wash a bite with copious amounts of water and check the wound for small teeth which the animal may have shed into the skin, which may later cause a foreign body reaction.
Can be very aggressive. Boas tend to be more aggressive early evening, so avoid these appointment times. Use a snake hook or similar device to locate and immobilise the head before putting the hand in the tank (even if the owner assures you the snake is tame). Hold the head with thumb and second finger behind the occiput and the forefinger on top of the head. Do not hold on `neck' behind head only as snakes have only a single occiput so one can easily dislocate the neck with rough handling of the smaller species. Care must be taken as bruising can lead to debility, even death as the myoglobin released can cause renal failure. The ribs of smaller snakes are delicate and easily broken. If bitten, remember the teeth angle to the back of the mouth so resist pulling back. Push hand slightly deeper into mouth and immerse head of snake into water until it releases. Drops of isopropyl alcohol into mouth encourage release. Larger snakes should always be handled in pairs (`buddy system') for safety reasons. NEVER allow a snake around your neck. The snake could potentially wrap around the neck remarkably quickly, causing fainting even if not strangulation. If a snake wraps around the arm, unwrap it from the tail end first whilst restraining the head. It is wise never to let go of the head of a snake when examining it. Even docile small corn snakes can bite then vet who is giving it unwanted attention. The common pet species are non poisonous, but some people (rarely) have a bee-sting like local reaction to snake saliva. Always wash a snake bite with copious amounts of water and check the wound for small teeth which the animal may have shed into the skin, which may later cause a foreign body reaction. Note: overhandling of reptiles, especially youngsters, can lead to food refusal. Reptiles are not social like most mammals and so tolerate moderate handling only. They should not be bought as pets to `cuddle'.
Sexual Dimorphism (species specific).
In the male the tail houses the hemipenes which may be seen bulging in mature lizards and snakes (more obvious in lizards). In chelonia, the penis makes the tail larger and longer, also the vent is further away from the plastron (the under part of the shell). Cloacal spurs are present in some male snakes. these are remnants of the pelvic limb.
They are present in all male boa constrictors but also some females (although they are generally smaller in females). Their presence is a very reliable indicator of the male sex in sand boas (Eryx spp.) and the rosy boa (Lichanura trivirata) but too variable in the Royal python (Python regius). The male Jackson's chameleon (Chameleo jacksoni) has three large rostral horns on his head. Most male reptiles are larger than the female of the species e.g. red-eared terrapins. Although this is not an accurate method of prediction. It should be noted that the secondary sexual characteristics will not be present in immature animals. Ultrasonography can be used to detect ovarian follicles and hemipenes/ penis in many species. Endoscopy can be used to visualise the gonads. The use of temperature dependant sex determination during incubation can be used to predict the sex of the hatchlings.
Length of tail (sub-caudal scale counts) in snakes
|Boa (Boa constrictor constrictor)||60|| 50 |
|Corn snake(Elaphe guttata)||67-86||41-62|
|Grass snake (Natrix natrix)|| 68-72||52-56|
|Royal python (Python regius)||40||27-36|
(count the number of scales in a line from the cloaca to the tip of the tail)
Pass an aseptic, lubricated metal snake sexing probe of appropriate size into the cloaca gently towards the tail. It passes into the inverted hemipenes in the male and so passes deeper than the female. Penetrating 6-8 sub-caudal scale lengths in the male, only 2-4 in the female. Use of appropriate sized plastic i/v catheter (with the inner metal needle removed) provides a cheap, sterile, disposable option. Check both hemipene orifices as smegma may sometimes block the invaginated hemipene, reducing the depth that the probe penetrates. Never force the probe in, or use a sharp object as hemipene lacerations, damage and abcessation are common sequelae of rough technique.
The hemipene can be `popped' out of the cloaca of even hatchling colubrids. The finger is rolled gently but firmly up the tail towards the cloca to evert the hemipene. Hydrostatic eversion may be used. A small amount of sterile saline is injection at the (presumed) position of the tip the inverted hemipene. the pressure forces the hempiene to evert out of the cloaca. This technique should first be practised on cadavers because of the potential risk of damage.
Femoral pores on medial aspect hind limbs more obvious in male than female. Some males have head ornamentation . hemipenes can be seen as bulges at base of ventral tail in sexually mature males Note: the green iguana only reaches maturity at 3- 4 years (3-6 foot length) when sexual characteristics will be obvious. Radiography of certain monitor species will reveal the os penis.
- male has longer tail than female, or more caudal vent
- male terrapin has longer forelimb nails than female
- male tortoise has concave plastron
Sharon Redrobe BVetMed BSc MRCVS
NVS / Exotic Species Vet
Small Animal Clinic
Phone: +44 (0)131 650 6074
Fax : +44 (0)131 650 6577
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Received May 1996
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