Abstract

With a large developing population of Komodo dragons at numerous zoological facilities, management techniques are requiring modification in order to handle animals that, at one point, could be easily restrained. A high proportion of deaths and reproductive medical problems in the adolescent female population in the last several years has also necessitated increased preventive medicine in the way of annual examinations, immobilizations, and venous access for clinical testing and treatments. As the Komodo Dragon Working Group begins transferring animals between institutions for breeding purposes, immobilizations for preshipment examinations are becoming increasingly necessary.

Successful management of adult Komodo dragons requires the ability to restrain and examine individuals at will, without subjecting them to substantial risk, stress, or injury. We describe husbandry and immobilization techniques which have proven safe and efficient. We also discuss the design features of the Memphis Zoo's Komodo dragon facility that allow staff to minimize stress or agitation of specimens and instead, exploit the intelligence of these uniquely trainable reptiles.

Exhibit Design and Husbandry Practices

Although physical contact with Komodo dragons is frequently warranted for veterinary care, it should be avoided while performing routine husbandry procedures. Not only does this eliminate repeated stressors, but it is also essential for the safety of animal staff because unprotected close proximity or hands-on contact with Komodo dragons always entails a degree of risk. These lizards are quick and powerful, and will defend themselves and their territory against perceived threats. With proper facility design, regular husbandry duties can be performed without handling the lizards or entering enclosures while lizards are present. The care of Komodo dragons in a zoo setting dictates that six procedures conducted frequently: feeding, indoor-outdoor transfer, introducing or separating individuals, visual examination, transport from the primary facility, and handling for procedures such as phlebotomy or treatment. The benefit of being able to perform these operations without handling or restraint of the lizards compels building planners to incorporate appropriate structures into new Komodo dragon facilities.

Feeding Komodo dragons, especially when several animals are housed together, is best done by hand to ensure that each lizard consumes the proper quantity. It is not safe for keepers to feed Komodo dragons while standing directly in their enclosures, particularly when more than one animal is present, as feeding responses are quickly directed towards any movement once the lizards are stimulated by the scent of prey. If keeper doorways into enclosures are fitted with protective features, such as divided, Dutch-style doors, a protective barrier between keeper and lizard can be maintained while still allowing animals to be fed individually from tongs.

Many institutions holding Komodo dragons are located in regions where winter temperatures require that lizards spend much of the time indoors. Such facilities usually provide access outdoors during the summer months to provide UV exposure. Shift doors that operate remotely allow lizards to be locked inside or out as temperatures dictate. The supreme intelligence possessed by these reptiles makes training them to shift in or out by voice or whistle command quite simple. At the Memphis Zoo we initiated shift training by luring lizards through the trap doors with a dead rodent held with tongs, and called the lizards’ names as they moved toward this object and through the passageway, giving the reward once the animal had completely shifted. Within a few weeks the lizards learned to move through the doorways when their names were called, without a food reward. The training appears permanent and continual food reinforcements have not proven necessary. Through this basic operant conditioning, we are able to move our Komodo dragons outdoors even during brief periods of warm winter weather knowing we can safely bring them back inside promptly when the temperature drops.

Many institutions maintain more than one specimen, usually with the intention of breeding the lizards at some point. Due to the substantial risk of lizards inflicting injury upon one another, dragon-to-dragon contact is best limited to brief periods when they can be kept under visual supervision. The need to move animals safely from individual housing into paired situations compels specific design elements be installed. At the Memphis Zoo’s Komodo dragon exhibit each of the three indoor enclosures is connected by two independent transfer chutes. At the point of connection with the enclosures at each end of the chutes, guillotine-style sliding doors are situated so that access to the chutes is under remote keeper control. An animal may be given access to the transfer chutes through an opening in the side of the enclosure and locked inside. The lizard can be subsequently released into the adjoining enclosure, or kept locked inside while the neighboring animal is shifted into another space by means of the second chute. Thus, having two secure avenues of transfer between each main enclosure allows staff to move any animal to any space without ever having to place two animals in direct contact. This ability is essential if two males are kept in the same building; even brief female to female contact may elicit aggressive behavior on occasion.

The need to perform veterinary procedures is usually determined following a visual inspection of a suspected problem. Since Komodo dragons require such large spaces, they can be difficult to scrutinize closely by veterinary staff. An area where the animals can be restricted and closely examined is necessary for proactive medical care. At the Memphis Zoo the transfer chutes previously described are affixed with small inspection doors along the top. These can be opened to gain direct access to the lizards within. The doors are made of framed Plexiglas so the position of the animal is known before the door is opened, an important safety consideration. The floor on which the chutes rest is heated with embedded elements, so lizards can be safely kept inside the devices as long as necessary without subjecting them to suboptimal temperatures.

If significant veterinary procedures are necessary, they will take place away from the primary facility where the lizards reside. Manually restraining and transporting an unanesthetized Komodo dragon through zoo grounds is dangerous for staff and the public as well as stressful on the lizard. Sedation in the primary facility prior to transport often requires preliminary restraint of a fully active specimen, which again poses risk and aggravation. The transfer chutes at the Memphis Zoo facility are portable units not attached to the building structure. A lizard can be shifted into a chute and locked inside. Thus secured, the entire unit can be carried out of the building and loaded into a vehicle for a quiet and secure trip to the zoo hospital.

Blood sampling for diagnosis, and administration of anesthetics or therapeutic drugs can be accomplished via access to the tail. Shift boxes can be designed to afford this access without gross restraint of a struggling animal. Once trained to enter a shift box, a sliding door with a hole cut in the bottom to the approximate diameter of the base of the lizard’s tail can be dropped after the lizard’s hindquarters have cleared the entrance. As soon as the door is secure, staff can grasp the tail as it protrudes outside the box. Blood can then be easily drawn or drugs administered. Komodo dragons can be prepared for this procedure by habituating them to having their tails held and manipulated. With repeated exposures, the lizards lose their fear of this sensation and cease to struggle, allowing a very simple and low stress means of treatment, phlebotomy, or anesthetic administration.

Perhaps the biggest current veterinary challenge associated with Komodo dragons held captive in temperate climates is that oviposition generally occurs during the time of year that the lizards must be kept indoors due to cool temperatures. Thus, an appropriate nesting area must be provided to permit gravid females to excavate the deep nesting burrows they require. Without this opportunity, females may suffer from dystocia, leading to serious and sometimes fatal consequences. An alarming number of female deaths in the captive population have involved gravid animals. Although the etiology of these deaths may involve several physiologic and husbandry factors, it is certain that without a proper nesting area for egg laying, grave health problems with adult females are likely to arise. The indoor enclosures at the Memphis Zoo have deep concrete-lined pits built into the floors. These pits are 2.2 m deep and are filled with sandy loam. The walls and floors of the pits are heated with independently controlled heating pipes so the bottom of the nest burrows will not be so cool as to interfere with ovipositioning. Our females use these pits readily when preparing to lay, and we consider them to be a critical component of our facility. Any institution housing adult female lizards, regardless of whether a male is present, should provide a proper laying area to avoid serious reproductive problems.

The overriding principle of Komodo dragon management at the Memphis Zoo is to avoid unnecessary contact with specimens during day-to-day care, and when veterinary needs call for direct contact, that it be accomplished quickly, effectively, and gently. Achieving this goal has required a marriage of meticulous veterinary science and thoughtful architectural planning.

Immobilization Techniques and Dosages

Due to the shift box design, access to the tail’s vasculature for drug administration is straightforward via the rear guillotine-style sliding door. In smaller Komodo dragons, utilization of a 1.5 inch 20- or 22-ga needle via a ventral midline approach to the ventral caudal vein is effective whereas with the larger dragons, a lateral approach just ventral to the musculature along the tail’s vertebral processes provides ready venous access.

Medetomidine and ketamine in combination have proven extremely effective for immobilizations. Onset of sternal recumbency takes place in less than 5 min and a plane of light anesthesia occurs at around 10 min (slightly longer in larger and/or more obese specimens). Muscle relaxation is more than sufficient to allow intubation or, for procedures lasting less than an hour, injectables alone have proven sufficient. The best aspect of this regimen is its reversibility. Atipamezole given primarily IV leads to a rapid reversal if the animal has been down a sufficient amount of time to allow the ketamine to be processed. Having a fully awake Komodo dragon within 10–20 min of reversal is an advantage in reptilian anesthesia that cannot be understated.

While intramuscular administration of medetomidine and ketamine is an alternative, we have found the anesthetic depth to be variable and the dosages required to reach light anesthesia via this route are higher (Table 1).

Table 1. Dosage and administration route of medetomidine, ketamine, and atipamezole