Captive u bandry of lubrid

Paul Raiti, D.V.M.

Beverlie Hospital, 17 W Grand Street, Mt. Vernon, NY 10552, USA

INTRODUCTION

Approximately 750/0 of the 3,000 of that have been classified belong in the family , the colubrid snakes. Colubrids can best be described as "typical" snakes and are considered to be the most advanced snakes. They have no vestigial hind limbs like the boids and possess only one functional right lung. Most colubrids kin by constriction or by simply overpowering its prey. such as mice and small rats for the bulk of their diet in captivity. Some colubrids are venomous possessing the Duvemoy's gland which is a modified salivary gland located in the rear of the upper jaw. Examples are the boomslang (Dispholidus ssp.), mangrove snake (Boiga ssp.), and Madagascar giant hognose snake (Uoheterodon spp.). Examples of nonvenomous colubrids that are commonly seen by veterinarians are ratsnakes ( ssp.) kingsnakes/milksnakes (Lampropeltis ssp.), gopherlbulllpine snakes (Pituophis ssp.), garter snakes (Thamnophis ssp.) and water snakes (Nerodia ssp.).

General husbandry

As a general rule snakes should be house individually except when paired for breeding. A 20 gal tank will suffice for most adult colubrids; however, larger specimens such as bull snakes and indigo snakes (Drymarchon ssp.) should be house in 30-40 gal tanks. Arboreal species such as the red­ tailed green ratsnake (Gonyosoma oxycepha/a) require taU cages. Secure lids are a necessity as snakes are expert escape artists. A hide box is important for the snake to feel secure. A sturdy water bowl that is large enough for total immersion should be provided at all times. Snakes from xeric habitats such as the trans-pecos ratsnake (Bogertophis ularis) need only be offered water once wee . e water should be changed every 48 hr to prevent overgrowth of bacteria such as Mycobacterium spp. Ca.ges sho thoroughly disin every four month with either Clorox bleach (1/4 clgal of water) or chlorhexadine solution (Nolv8san, 2 Tbls/gal). Newspaper is an appropriate substrate because it is readily available, permits early detection of waste material and is nontoxic. Other commonly used substrates include pine shavings and outdoor carpeting. Most colubrids can be maintained at a temperature gradient of 75-80 OF during the day with a night time decrease of 5°. Examples of heat sources are heating pads, spot lights and electrical tape. The use of hot rocks is discouraged due to the possibility of inducing thermal bums. A photoperiod of 12 hr daylight should be provided to encourage normal behavior. It is not considered necessary to proved a source of UVB iation. Most colubrids are active predators with a relatively high metabolic rate. The average gastrointestinal transit time is approximately 3-4 day. Feeding frequency can be once weekly. The average adult length of colubrids is 3-6 ft. Individuals of this size may be fed either one to three mice or one small rat weekly. Except for those specimens that only consume live food it is recommended to feed thawed or freshly killed rodents. Ecdysis (normal shedding) occurs throughout the snake's life. During the shedding period it is normal for the snake to refuse food. It may spend more time soaking in the water bowl to facilitate this process. An object with an abrasive surface should be present in the cage so that the snake can properly initiate shedding. Normally, snakes slough their skin in one piece. If the epidermis peels away in patches it is usually due to low ambient

1996 PROCEEDINGS ASSOCIATION OF AMPHIB~N AND REPTILIAN VETERINARIANS 73 humidity. This can be corrected by daily misting or placing a shallow bowl filled with moistened sphagnum moss in the enclosure. Accurate record keeping is an overlooked aspect of husbandry. Three by five inch index cards can be taped to the sides of the tanks and should contain notations regarding dates of feeding, shedding, periodic weights and veterinary care.

Hibernation

Temperate colubrids normally become anorexic during the fall season. Most herpetoculturists cool their snakes during winter in order to cycle them for breeding the next spring. Even if breeding is not desired it is recommended to simulate this metabolic slowdown because ' physiology is designed to have periods of inactivity. During that time fat reserves are metabolized and the hypothalamo-pituitary-gonadal axis stimulated. To prepare for this event all food should be withheld 3 wk prior to cooling. This minimizes the risk of decomposition of ingesta in the digestive tract. Snakes are then cooled from the first of December through the first of March in a darkened room. They should be gradually warmed 2 wk prior to spring emergence. The average hibernation

mperature is approximatel 55 OF e During this time the snakes should be checked every 2 wk. Snakes shou be provided with water as they win continue to be moderately active passing urates, drinking and occasionally shedding.

Reproduction

After snakes have been removed from hibernation the males can be placed on their regular ing program; however, the males shOll fed heavily in anticipation of vit lagenesis (yolk formation) which is d dent on their fat reserves. Females can be fed every 3 d instead once weekly. A few weeks after hibernation the snakes shed their skins. For the female this is referred to as the preovulatory shed and it signals the time that the female should be introduced the malEt Obviously, pairing properly sexed individuals is essential to having a successful breeding program. The most accurate method used to properly sex snakes is probing whereby appropriately sized stainless steel instruments are ntly inserted into the tail via the cloaca. Males probe to a depth of 12 subcaudal scales and probe to a depth of 2..4 s. the female, developing f lides can be seen as a mid swelling and are palpable as multiple soft tissue densities. Before ovulation, copulation occurs and may continue intermittently for a 2 wk period. If successful fertilization takes place, the caudal part of the female's body win appear swonen~ The next shed is referred to as the pre-egg-Iaying slough cause 1-14 day later oviposition occurse A suitable damp substrate as moistened sphagnum moss or pine shavings should be provided for the fem . The water bowl should be removed from the cage so that the eggs win not be deposited in the water~ A clutch us Iy consists of 4 eggs being passed during a 24 hr period. After oviposition the 8g to e other. These can be gently placed in an incubator (Hovs-bator) being careful to rotate them. Vermiculite mixed with water in a 1:1 ratio by weight works wen as a substrate. The average incubation temperature is maintained at 80...84 OF with a slight drop of 2° at night The eggs should be checked once weekly. Viability can be checked by candli whereby a bright light source is held up to the egg and one looks for vascularization of the contents. Ifthe eggs begin to collapse prematurely this means that they are becoming dehydrated; consequently, more water should be added to the substrate. If the eggs swell excessively it is likely that the substrate is too wet and should be changed.

1996 PROCEEDINGS ASSOCIATION Of REPTILIAN AND AMPHIBIAN VETERINARIANS 74 Neonatal care

Emergence of the neonates occurs approximately 60-70 day after oviposition. Each snake contains a caruncle (egg tooth) which it used to make multiple slits through the shell. All the eggs should have pipped within a 48 hr period. For those eggs that have not pipped an incision can be made with a small pair of scissors just large enough for the snake's head to come out. The neonates usually remain in the shells for a few days during which time they absorb the rest of the yolk sac. After the snakes have completely hatched they should be placed in individual containers. There is no need to offer food until after the first shed which occurs 1-2 wk later. Most neonates will readily consume pinkies (newborn mice). For those recalcitrant feeders juvenile anoia or gecko! can be utilized. Juvenile snakes are usually not hibernated until they are at least 1 yr old. Most colubrids reach sexual maturity by 3 yr of age whereupon the breeding cycle is initiated. The average life span of colubrids in captivity is 13...33 yr of age.

REFERENCES

Coborn, J. 1991. The Atlas of Snakes of the World. TFH Publications, Neptune City, N.J. Mattison, C. 1991. A....Z of Snake Keeping. Merchurst Press, United Kingdom ___,_. 1994. A Practical Guide to Exotic Pets. Running Press, Phils Iphia, Pa. Mehrtens, J. 1987. Livi akes of the erld in fa Sterling Publishing, New York, N.Y. Raiti, P. 1995. Veterinary Care of the Common Kingsnake, Lampropeltis getula. Bulletin of the A ,5(1): 10. Rossi, JV. 1992. Snakes of the United States and Canada: Keeping Them Healthy in Captivity. Krieger Publishing Co., Malabar, FL Snider, AT. and JKBowler. 1992. Longevity of Reptiles and Amphibians in North American Collections. SSAR, Herpetological Circular No. 21.

1996 PROCEEDINGS ASSOCIATION OF AMPHIB~N AND REPTilIAN VETERINARIANS 75