20 May Reptile Husbandry
By Robert Johnson BVSc MACVSc Cert BA
The most common cause of disease in captive reptiles is incorrect or poor husbandry. A sound knowledge of reptile husbandry is required to prevent diseases. Environmental and dietary needs must be considered carefully. Specific requirements of some species of reptiles are mentioned below.
The eight H’s of husbandry
· Healthy appetite
Heat (and light)
Reptiles are ectothermic vertebrates that regulate body temperature by behavioural and physiological processes. Reptiles should be housed at temperatures similar to field conditions, providing temperature variation within the enclosure that allows the animal to choose its thermal environmental (thermo regulate).
A thermo gradient or “mosaic” is achieved by having sufficient room to place heat sources strategically within the enclosure. Two main types of heating are used by herpetologists, radiant (lamps, ceramic globes) and convective (heat mats, tape).
“Hot rocks” are not recommended as heat sources. Snakes will tend to bask on them for extended periods occasionally sustaining burns. This occurs more often in snakes that have recently undergone ecdysis (sloughing); it has been shown that large reptiles rely primarily on radiant heat sources for thermoregulation whereas smaller species tend to depend on connective sources. Terrestrial or ground dwelling snakes such as pythons (Anaresia children) prefer sub floor heating. Ambient room temperature should be stable and not place undue stress on the thermo gradient in the vivarium. Mistakes are commonly made when enclosures are kept in rooms subject to temperature extremes.
Preferred body temperature (PBT)
The preferred body temperature is the temperature at which metabolism is optimal. The preferred optimal temperature zone (POTZ) is the range that allows the reptile to achieve its PBT. Preferred body temperature varies with species (see table below)
Some reptile owners do not recognise the difference between a thermostat and thermometer. It is important that they realise that the readings on most thermostats are only a guide. Thermostats must be calibrated for individual enclosures using a thermometer.
Ultraviolet light is essential for the synthesis of vitamin D and calcium metabolism. Among commonly kept Australian species, eastern water dragon and bearded dragons need ultraviolet supplementation when kept indoors (UVB 280-315 nm). Ultraviolet light sources need to be replaced according to manufacturer’s instructions. There is some discussion as to whether the diamond python (Morelia spilota spilota) requires UVB supplementation in captivity.
All captive reptiles need somewhere to hide. Items such as toilet rolls or small cardboard boxes are ideal for hatchling snakes and the smaller terrestrial varieties. When soiled simply replace them. Porcelain hides and inverted flower pots are also popular. These structures must be waterproof and easy to disinfect. Certain species are more secretive compared to others e.g. Antaresia spp (children’s pythons). Large vivaria (enclosures) should be furnished with several hides in a variety of positions in order to facilitate thermo regulation. Hides can be used as an aid to handling. This is especially relevant to more aggressive or venomous species. The entrance to a favourite shelter may be blocked securely and then used to transport the reptile.
Humidity requirements vary with species (40-80%). For example, the environment of a green python needs to be much more humid than that of the inland bearded dragon. All snakes need a large water bowl for bathing and drinking. The humidity of a vivarium can be controlled by altering the size of the water bowl. Always place it at the cooler end of the exhibit, except in cases where a rapid increase in humidity is required. In these cases a heat lamp or mat may be placed under the water container to aid evaporation. All varia, dry and humid, should be adequately ventilated.
The health of the captive reptile is inextricably linked to the husbandry practices employed (see separate handout on common diseases). So good husbandry practices usually means healthy reptiles.
Good hygiene is dependent upon the use of an appropriate substrate and good disinfection and cleaning practices.
Substrates vary according to the special needs of a species. Newspapers or butchers paper is suitable for arboreal species such as diamond and carpet pythons. Terrestrial species such as children’s pythons and blue tongue lizards do best on pelleted newspaper “Kitty Litter” products. Hatchling and small pythons should not be fed in containers with pelleted newspaper substrate. Pellets may be inadvertently swallowed, causing intestinal obstruction. The feeding area should be a separate container lined with paper. Bearded dragons thrive on fine sand. Gravid females need a suitable substrate for digging and oviposition. Artificial turf, bark chips and dirt are unsuitable and provide good media for bacterial and fungal growth.
The commonest cause of disease in captive turtles is poor water quality. Water should be tested daily using a standard aquarium kit, measuring PH, ammonia levels, nitrites and nitrates. Minor skin aliments will heal if the turtle is removed from the water for a short period. It is preferable to feed turtles in a separate tank. This will avoid contamination of the water with food particles.
Dietary needs vary greatly in Australian herpetofauna, depending on species, size and state maturity. Blue tongue lizards start off life as insectivores and molluscivores and gradually become omnivores in their feeding habits. Bearded dragons similarly begin as insectivores and as they mature develop a taste for vegetables and some fruits. All Australian snakes are carnivorous. Python Hatchlings will eat small pinkie mice. As they grow food items should be larger (pinkie-fuzzy-weaner mice, adult mice, rats) and feeding intervals further apart. Hatchlings are generally fed every 4-5 days, while an adult python may be fed every 1-2 weeks. Small lizards need to eat daily or at least every second day. Adult lizards are usually fed every 2-3 days.
Turtles will normally only eat in water. Some may be trained to accept food out of water. Usually reptiles are fed no more than 20% of their body weight at a time. All mammalian prey items must be pre-frozen (preferably 4 weeks at least) for animal welfare reasons and to limit parasitism. Never feed snakes together in the same vivarium.
Habitat- Huge or small?
Novice reptile keepers frequently make the mistake of transferring a hatchling or small snake to a large vivarium. Snakes should be always housed so that they can stretch to their full body length but very large enclosures may make it difficult for small reptile to thermo regulate. Small plastic pet containers are sufficient for hatchling pythons. Sub-floor heating is usually provided by heat mats or tape. According to some authors the size of the cage may not be as important as how it is furnished.
Reptiles, especially snakes and small lizards should not be over handled. Snakes should not be handled for at least 3 days after eating due to the risk of regurgitation. Hands should be washed before touching reptiles to limit the spread of disease and to be rid of any mammalian scent. A snake will strike instinctively if it can smell mammals. Frequently reptiles are brought to the clinic draped around the arm of their owner and not in a container. This can be stressful for the snake and non reptile owning clients in the waiting room. Such practice is to be actively discouraged. A pillow case makes a very good carry bag for most sized snakes.
SPECIES Preferred Body Temperature (PBT) in *C
Long-necked turtle 26
Children’s python 30-33
Carpet Python 29-33
Water Python 34
Diamond Python 29
Amethystine Python 33
Common tree snake 32
Saltwater Crocodile 33
Common Blue Tongued Lizard 28-32
Shingleback Lizard 33
Cunningham Skink 33
Bearded Dragon 35-39
Lace Monitor 35
Gould’s Monitor 37