Medical Management of Tigers

Adapted from M. Bush, L. Phillips, and R. Montali, 1987. Clinical management of captive tigers. In: Tigers of the World: The Biology, Biopolitics, Management, and Conservation of an Endangered Species. Noyes Publ., Park Ridge, NJ. With a section by N. Reindl, Minnesota Zoo, and significant contributions and additions by D. Armstrong, Omaha's Henry Doorly Zoo.

Overview

Although tigers are displayed in most zoos, and they have a long history in captivity, surprisingly little medical data have been published. Most published reports concern medical problems that are preventable, given the present state of the science of zoological medicine, namely dietary related deficiencies and diseases or viral infections.

Previous documents on medical support of endangered species have been formulated under the usual heading of "Disease." This inadvertently places the veterinarian in a reactive rather than an interactive role as a member of the conservation team. Our approach is to consider an overall medical program for the tiger that will not only minimize disease but improve overall viability. The emerging role of medical programs is to shift strategies from the care of individuals to the care of species, subspecies, and populations.

The medical and surgical care of captive tigers has become easier with advancements in other areas, especially in anesthesia and anesthetic techniques. Major nutritional problems are almost nonexistent due to the increased understanding of dietary needs including proper ratios of vitamins and minerals. The majority of contagious infectious diseases can be prevented by appropriate vaccines. Parasites (external and internal) can be effectively controlled or eliminated with newer drugs.

The present challenge to zoo staff, particularly the veterinarian, is to establish and maintain a strong and aggressive preventive medical program. Once this is instituted and functioning, the major medical problems encountered will be the geriatric problems of an aging collection.

Medical management of captive tigers requires the integration of preventive medical programs, clinical medicine, nutrition, husbandry practices, and pathological surveillance. The preventive programs have matured to meet the needs of the species. We continue to promote medical programs that are aggressive rather than reactive. The following protocols outline the necessary components of such a program for the medical management of captive tigers.

The scope of preventive medical procedures is extensive, from the time the animal enters the collection (i.e., birth or transfer) to its disposition to another zoo, or to a complete post-mortem examination when it dies. Specific preventive factors relate to diet, exhibit design, behavioral needs, cleaning procedures, pest control and the more medically oriented procedures such as vaccinations, parasite control and quarantine.

In dealing with tigers, it has been stated repeatedly they are just big domestic cats that share many anatomical, physiological, behavioral, and medical commonalities. Fortunately, this allows veterinarians to extrapolate from experiences and expertise dealing with the domestic counterpart. It is best not to be overzealous in utilizing this comparison since tigers are unique animals; new problems and new techniques should be approached through careful planning and good clinical judgment. One should always be ready for the unexpected.

Shipping and Quarantine

The long-term management of the health of tigers begins before the animal arrives with appropriate planning of the management program and with arrangements to transfer and receive the animal that protect its health.

Shipping Procedures

Shipment procedures for tigers require good organization to minimize stress to the animal. Before shipment the health status of the tiger is evaluated. If possible, the animal should have access to its shipping crate for two weeks prior to shipment to become familiar with it. The tiger should definitely be fed in it. In the United States, the design of the crate must meet the U.S. Department of Agriculture (USDA) requirements and be strong enough to safely hold the tiger (see Crate Specifications below). For international shipments, International Air Transport Association (IATA) requirements must be met, and these provide reasonable guidelines for most tiger transfers. If an extended trip is anticipated (more than 12 hr), provisions should be made for someone to offer water and food to the animal while in transit. In reality, however, tigers are unlikely to feed in transport and can easily go for a few days without food. Water is more crucial, and arrangements must be made to provide an adequate water supply for tigers in transit over 12 hours.

When a tiger is moved, one of its keepers should accompany it to care for it in transit if the transport involves more than one transfer en route, if travel time from airport drop-off to airport pick-up is more than 12 hours, and if it is a very young cub. A keeper familiar with the tiger may help it adjust to its new environment. Husbandry, dietary and medical records should be transmitted to the receiving institution prior to shipment, and complete copies of these records should accompany the tiger during shipment. It is important that any tiger tranquilized for shipment be completely awake and standing before it travels. Tigers are lost even under the best intentions, as shown in this excerpt from the Los Angeles Times, Wednesday, March 25, 1992.

DEATH OF RARE MALAYSIAN TIGER ON FLIGHT TO U.S. IS REVEALED

SAN DIEGO--A rare Malaysian tiger, one of only about 200 in existence, died while being flown from Kuala Lumpur to Los Angeles after being placed by Malaysian authorities in a crate that was partly wrapped in plastic and barely larger than the animal itself, said authorities. The 100-pound female tiger was one of two 10-month-old sister cubs that were destined for the San Diego Zoo.

The animal was ailing--if not already dead--when a Malaysian Airlines 747 stopped for two hours in Honolulu and ground cargo handlers said they smelled something foul. But before a veterinarian for the U.S. Department of Agriculture could arrive at the airport to check on the animal's condition, the airliner already had taken off for Los Angeles.

When the plane landed at Los Angeles on Feb. 19, concluding the 24-hour trip, the cub was dead, either from dehydration or because it apparently had overheated in its small wooden cage, said Dr. Ron DeHaven, animal care supervisor for the USDA in Sacramento.

"The cage was barely larger than the animal itself," DeHaven said. "It literally could not stand up in the crate. There was no ventilation. It was a solid wooden crate except for one end, the tail end, where there was heavy gauge wire. "But the crate was wrapped in plastic halfway up, so that half was cut off to ventilation," he said. The animal was 43 inches long from the crown of its head to the base of its tail, and the cage was just 46 inches long, a USDA inspection showed. The cage was 23 inches in height and 22 inches wide.

A shipping crate should be well ventilated, drain well, and absorbent bedding be provided to prevent the tiger from lying in urine. The crate must be strong enough and large enough for the tiger, but the size should allow easy movement and access through doorways. Particular attention should be paid to the size of doors on all airplanes on which the tiger may be transported.

Crate Specifications

(N. Reindl) All shipping containers for tigers other than cubs of under 15 kg should be constructed of steel or 1/8" thick aluminum. If wood is used, all interior surfaces must be metal-lined and free from sharp projections and edges. Basic design allows free flow of air through both ends of the container, but the design must be such that the tiger can not reach out to injure attendants. Use of a double door design on each end allows for a barred end gate, which provides containment for the animals. A second thin panel of expanded metal provides safety for the handlers working around the crate, yet can be lifted as needed to service the animal if delays occur or treatment is necessary. The doors on each end of the crate should be guillotine style to facilitate animal

Crate Size Inside Dimensions (in cm)Outside Dimensions
LengthWidthHeightLengthWidthHeight
Large: adult male 183 56 76 198 74 97
Medium: adult female 152 51 66 168 69 86
Small: sub-adults 122 46 61 137 64 81
X-small: cubs 91 41 56 107 58 76

Fig. 1. Schematic view of a typical shipping crate (U.S. Dep. Agric., 1980).

A large crate loaded with an adult tiger can weigh over 400 kg. It is essential that adequate handles are provided along the full length of each side of the container and that the bottom is raised with skids to allow the use of mechanized lifting equipment (fork lift). The International Animal Transport Association (IATA) standards follow.

USDA REQUIREMENTS

(from Live Animal Regulations, International Air Transport Association, 1991)

Principles of Design

The following principles of design shall be met in addition to the General Container Requirements outlined by the U.S. Department of Agriculture (see below).

The front end shall be formed of steel welded mesh or strong iron bars. The bars must be spaced in a manner which will prevent the animal from pushing its forelegs through the spaces between the bars. A sliding door shall be constructed at the rear, of the same material as the container, adequately secured to prevent accidental opening.

The floor shall be constructed in grille form over a liquid-proof tray in a manner to permit the animal's excreta to fall into the tray. When a grill floor is not feasible, the floor of the container must be liquid-proof and be covered with sufficient material to absorb the animal's excreta.

To ensure adequate ventilation, air inlets must be provided at heights which will provide through ventilation at all levels, particularly when the animal is in a prone position. Ventilation holes, of approximately 2.5 cm (1 in) diameter, shall be positioned on the sides and top as indicated in the diagram. These holes may be screened on the exterior with fine nylon or similar mesh if such covering will not unduly restrict the amount of air entering the container. While loosely woven burlap may also be used when it is necessary to quiet the animal, great care must be taken to ensure that air circulation is not restricted. Burlap covering must be readily removable to allow increased air flow, as necessary.

To prevent disturbance to the animal and to provide protection for the handling personnel, wooden slotted shutters with adequate ventilation slots or holes should be placed over the front opening, approximately 7.5 cm (3 in) away from steel weld mesh or iron bars. Loosely woven burlap or fine nylon or similar mesh, stretched over the front opening, with a batten on the bottom, can be used in lieu of the wooden shutters.

The dimensions of the container shall allow the animal to turn completely around freely, or shall prevent it from turning at all. The height shall provide adequate space for the animal to stand upright with head extended, the length shall permit it to lay in the full prone position. Actual container dimensions vary according to species and size of animal.

Food and water containers with adequate safe access for replenishment must be made available by the shipper, taking into account the duration of the flight.

Where more than one animal is to be carried in a container, multiples of the above provisions shall apply. Divisions can take the form of partitions such as metal grills. Compatible animals need not be separated by a partition when it is probable they will not harm each other during shipment.

Quarantine Procedures

Prior to the introduction of any new tiger to an existing population, the newcomer should be quarantined for at least 30 days. Ideally the tiger will be held in a separate facility and cared for by keepers that do not care for other felids. Unfortunately, this may not always be possible. In these instances, the tiger should be separated from other cats as much as possible, and keepers should work with it after they have finished all work with the existing collection. Personnel working with or near a quarantined cat should wear coveralls and rubber boots designated for the quarantine area. A foot bath in and out of quarantine helps prevent potential contamination. The quarantine area should have drainage separate from other cat facilities. Separate cleaning tools that are not removed from the quarantine area are a necessity.

Quarantine protocol for tigers (see Table Checklist) should include a parasite screening, complete physical examination, collection of a blood sample including serum sample banking, and preventive medical procedures such as immunizations and dental calculus removal. An animal should be observed carefully during the quarantine period, and factors such as the animal's behavior and appetite, and subtle symptoms of potential disease should be recorded daily.

The quarantine period allows observation and testing to monitor the animal for infectious diseases and/or parasites. The 30-day period is adequate to cover the incubation period of most infectious diseases. Animals newly captured from the wild may require a longer quarantine, particularly when treatment of parasites or disease problems is required.

The evaluation of a new tiger begins with a review of its past medical history, which should be part of the health certificate. It is unacceptable to send an animal to a new collection without sending its medical history. These data will alert the clinician to previous and potential problems and document past vaccinations, anesthetic doses, medical procedures, identification methods, fecal examinations and blood values. Body weights should be obtained on all tigers entering and leaving quarantine. It is recommended that each cat be individually identified with a subcutaneous microchip (transponder) and a tattoo of the studbook number. The placement of transponders and the location of tattoos have been directed by the American Zoo and Aquariums Association (AZA) Tiger Species Survival Plan (SSP) but may undergo review (especially the transponder placement).

Change in Diet

When in quarantine, the tiger's diet is gradually changed to the new diet if different from the original. Any dietary alterations should be gradual to minimize gastrointestinal upset. It is not unusual to have a newly arrived tiger stop eating because of the environmental change. The Minnesota Zoo reported an adult female that refused to come into holding from her exhibit and did not eat for 19 days; an adult male from the Moscow Zoo never did switch over to zoo diet for its entire life. In some cases it is advantageous to have some of the animal's previous diet accompany it if the food is not available locally. To stimulate appetite, whole carcasses of rabbits or chickens may be offered.

THE UNITED STATES DEPARTMENT OF AGRICULTURE REGULATIONS

USDA introduced new regulations on 15 January 1980 relating to the importation of pet birds into the United States. These requirements also pertain to tigers.

Rules

  1. Animals imported into the United States must be accompanied by a veterinary health certificate;
  2. a request for quarantine space must be made by the importer and accompanied by a reservation fee prior to importation;
  3. a 30-day quarantine period at owner's expense will be completed at specified quarantine facilities;
  4. these rules provide for re-entry of pet birds properly identified, of United States origin which have been out of the country, when accompanied by a veterinary health certificate issued prior to departure from the United States, and the bird is identified by a leg band with the number affixed to the health certificate.

USG-02

No warm-blooded animals, including birds, can be presented to a carrier more than four hours before the aircraft's scheduled departure time. If prior arrangements are made, a six-hour maximum is acceptable.

USG-03

There are specific rules, within the USA, for the animal holding areas in cargo terminals. According to the Animal Welfare Act, a temperature range of 7.2 C (45 F) to 23.9 C (75 F) is normally acceptable. Note a temperature range of between 23.9 C (75 F) to 29.5 C (85 F) is acceptable for a four hour time period only. Animals being moved between the animal holding areas in cargo terminals and planes on the ramp may be subjected to temperatures exceeding 29.5 C (85 F) or 7.2 C (45 F) for no more than 45 minutes.

USG-04

Animal shipments to, from or via the United States must have written instructions concerning the food and water requirements of the animal affixed to the outside of the container.

USG-05

All containers for dogs and cats must be of such a size to allow the animals to turn around.

USG-06

For the carriage of warm-blooded animals, there must be ventilation openings on two opposite walls, which openings are at least 16% of the area of each wall, or ventilation openings on all four walls, which openings are at least 8% of the area of each wall; and at least one-third of the minimum ventilation area must be in the lower half of the container and one-third in the upper half. In addition, for dogs and cats, if there are ventilation openings on three walls they must be at least 8% of the area of two opposite walls and 50% of the area of the third wall: the total combined ventilation opening area must be at least 14% of the total combined area of all four walls. The outside of the wall with ventilation openings must have a rim or other separation device 1.9 cm (3/4 in) deep to prevent obstruction of ventilation openings.

USG-07

Animal shipments to, from, or via the United States must be marked or labeled on the top and on one or more sides of the container with the words "Wild Animal" in letters not less than 2.5 cm (1 in) in height and arrows or markings indicating the upright position.

USG-08

A maximum of one live dog or cat, six months or more of age, or a maximum of one live puppy, eight weeks to six months of age and weighing over 9 kg (20 lb), shall be transported in a primary enclosure. Two live puppies and kittens, eight weeks to six months of age, but not weighing over 9 kg (20 lb) each and of comparable size, may be carried in the same primary enclosure. Weaned live puppies or kittens less than eight weeks of age and of comparable size, or puppies or kittens which are less than eight weeks of age, and litter-mates accompanied by their dam, may be shipped in the same primary enclosure to research laboratories.

USG-09

The U.S. Animal Welfare Act, Section 3.86(a), requires that one-third of the container ventilation holes must be in the lower half of the container.

Routine Health Management

Medical Records

The systematic gathering and recording of medical and pathological data in a uniform manner is mandatory to any medical program. These records contain vaccinations, diseases, surgeries, anesthetic episodes, parasite problems, weights, medications received, blood and other clinical pathology data, etc. It is vital to start this during the quarantine period and continue it through the animal's life in the collection and then, if the animal dies, the necropsy findings will be part of the record. There are computer programs to compile and manage these data (e.g., MedARKS from International Species Information System, ISIS). If computers are not yet available, then complete written records should be maintained and thought should be given to developing codes that will help entering these data into a computerized record system at a later date. The value of medical records cannot be overemphasized.

Identification

(from the editors of this volume)

The ability to absolutely confirm an animal's identification is essential to any species management program either within a zoo or on a regional, national or global level. Individual identification is also essential to the accuracy of medical and animal management records. Each individual tiger should be permanently identified by at least two different methods. At the present time the two most dependable methods are the tattoo and the transponder. Tattoos may be placed in various locations. The medial (inside) surface of the upper rear leg is used in many tigers. This location is large enough to permit large, legible tattoos to be placed while not normally being visible when the tiger is on public display. The tattoo placed must be an identification number unique to that individual tiger, such as the animal's permanent studbook number.

Glass-encapsulated microchip transponders placed subcutaneously in the tiger provide a second permanent identification method. The use of a standard system and transponder location simplifies the identification of tigers transferred between institutions. At the present time, the IUCN/SSC Conservation Breeding Specialist Group recommends the use of the Trovan transponder system (Infopet Identification Systems, 415 W. Travelers Trail, Burnsville, MN, USA 55337; phone 1-800-INFOPET, or 612-890-2080) with transponders placed at the base of the left ear in tigers. Transponders have also been placed interscapularly in tigers.)

Serum Banking

(from the editors )

A bank of frozen serum samples stored in an ultra-low-temperature freezer at -70 C should be maintained at each institution. This serum bank should contain a 5 to 20 ml sample of serum from each procedure in which blood samples were collected from any tiger in the collection.

The serum bank permits retrospective epidemiological studies when a disease outbreak has occurred or new disease entities have been identified. Individual serum chemistry analyses can be evaluated on banked samples to evaluate health parameters that may not have been performed when samples were initially collected. Surplus banked serum can be used as an antibody source to provide passive immunity to tiger cubs when there is a failure of passive antibody transfer from the dam of the cubs such as in hand-rearing situations. However, passive immunity transfer requires large volumes (100 ml) to be effective, and extra serum should be banked for this purpose.

Adult Anesthesia

Anesthesia is a critical component of the overall medical program in all nondomestic felids. Anesthesia allows the veterinarian safe access to the patient for diagnostic, therapeutic, surgical and research procedures. The state of the art and science of anesthesia in this species has advanced so that the procedure is expected to be routine and safe. When problems occur, overall medical and research programs are potentially endangered. Therefore, safe anesthesia through appropriate techniques is mandatory. Veterinarians wanting more detailed information on this subject can write Dr. Ronald Tilson, Conservation Department, Minnesota Zoo, 13000 Zoo Blvd., Apple Valley, MN 55124.

Complete Physical Examination

Usually two to three weeks into the quarantine period a complete physical examination should be performed under general anesthesia. Complete physical examinations should subsequently be performed on an annual basis. This exam should include evaluation of each organ system following a regular protocol to assure completeness. The exam should include the following (see checklist, Table 1):

  • Rectal body temperature
  • External: eyes, ears (ear mites), pelage (external parasites), feet and claws
  • Oral cavity: the pharynx, gingiva and particularly the teeth for calculus or exposed root canals
  • Palpation of limbs, including movement of joints, lymph nodes, and abdomen to detect the presence of organ enlargement, fluid, or masses
  • Auscultation of the thorax for pulmonary and cardiac assessment (rate and rhythm)
  • Body weight
  • Blood sample for hematological and clinical chemical screening and for serum banking

Table 1. Checklist of routine examination procedures for felids during quarantine, the ongoing preventative medical program and prior to shipment (ACN=as clinically needed).

QuarantineOngoingPreshipment
Physical Exam + + +
Blood Sampling

CBC, Chemistries

+ + +

Serum bank

+ + +
Radiographs + ACN +
Fecal Examination + + +
Fecal Culture + ACN +
Vaccinations

Fel-O-Vax

+ + +

Rabies (killed)

+ + +
Dental Examination + + +
Body Weight + + +
Transponder + check check
Tattoo + check check
Viral Screen (includes FIP) + + +

For a more thorough physical examination, a complete set of survey radiographs is recommended to assist in the overall assessment of the tiger and as a reference set for the future. In addition, semen collection via electroejaculation is recommended for unproven adult males destined to be breeders. Complete physical examinations should also be performed at the time of more targeted examinations for specific health problems. A protocol for regular physical examination should be established in order to monitor health over time as a component of an overall preventative medical program.

Dental Examination

A thorough oral examination is an integral part of a physical exam, either planned or done whenever anesthesia is performed. As a tiger ages, this examination becomes more important for prevention of dental problems causing systemic diseases. The oral examination should include dental structures for fractures and periodontal disease. A common problem reported in exotic felids relates to wear or trauma from fighting between tigers or contact with enclosure material. The most common dental finding is calculus accumulation, especially along the buccal surface of the upper molars and premolars.

During the examination, the teeth and the soft tissue structures of the mouth and throat are examined for abnormalities. Odor from the mouth may prove to be an important indicator of a dental problem. Foreign bodies lodged between oral structures, such as bone fragments or sticks can be incidental findings but predisposes the animal to oral disease. These should be removed and infections or traumatic lesions treated as indicated.

Blood Baseline Values

During quarantine, a blood sample should be obtained to evaluate the animal's health status and provide a baseline for future comparison. An initial blood sample can be taken prior to anesthesia by placing the tiger in a squeeze cage and bleeding it from the lateral tail vein. This will help evaluate the animal's status prior to anesthesia for a complete physical examination. It is recommended that all zoos participating in the AZA Tiger SSP have access to a squeeze cage. Clinical parameters of primary interest are total WBC count and differential, hematocrit, BUN, creatinine, liver enzyme values and an examination for red blood cell parasites. A summary of normal blood values for tigers is listed in Table 3 (compiled by ISIS). It should be recognized that values may differ between various laboratories, and the best set of values is the one that your laboratory compiles.

The collection of blood samples for laboratory evaluation and serum banking should be a part of every immobilization or physical examination.

Table 2. Normal blood values for Panthera tigris (compiled by ISIS).

Preventative Medical Procedures

Preventive medical programs during quarantine have been stressed in the opening section. It is important to continue this concept as an ongoing program in the captive maintenance of the tiger.

An important portion of this preventive approach should include routine observation of the tigers in the collection, not only by the keepers, but also by the veterinary staff. Routine rounds through the cat area should be made to remain familiar with the tigers, to evaluate their overall appearance, activity, and facility conditions, and to talk with the keepers. The veterinarian's experience allows him/her to detect an abnormality or develop an impression about the tigers' health and management that may not be obvious to the keeper staff. Familiarity with normal conditions in tigers will allow a better comparison when the animal is suspected of having an abnormality. A good relationship with the keepers promotes open communications between the animal and veterinary staff, which is vital to any medical program. There are potential limitations to these visits, since many large felids including tigers recognize the veterinary staff and associate them with some past negative situation usually involving a manipulative procedure. These tigers can react aggressively, which masks the subtle first signs of many medical problems; therefore the medical staff must carefully consider keepers' observations concerning subtle changes in their tigers.

Immunizations

Vaccinations given during quarantine allow time for antibody response prior to the tiger's release to the collection. Severely stressed animals may not mount appropriate titers and should be re-vaccinated if conditions indicate. Tigers that have never been vaccinated previously will require at least two vaccinations, three weeks apart, to produce adequate antibody levels. Subsequent vaccinations to maintain protective antibody levels should be provided at least annually throughout the animal's life and in some cases more frequently.

All vaccines used should be killed vaccines whenever possible in order to prevent the occurrence of vaccine-induced disease. No modified live vaccines have been adequately tested in tigers.

Panleukopenia, Rhinotracheitis and Calicivirus. Panleukopenia (feline distemper), rhinotracheitis and calicivirus are the most common viral infectious diseases of domestic cats. There is one vaccine that provides good antibody titers to these three major infectious viral diseases. This is a killed product, (Fel-o-vax, Fort Dodge Lab Inc., Fort Dodge, IA 50501) and provides apparent protection at a 1-ml dose (domestic cat) in adult tigers (Bush et al. 1981). The European Endangered Species Program (EEP) recommends 1 ml of Fel-O-Vax be used for boosters in adults; juveniles should be vaccinated at 8, 12, and 16 weeks, repeated at six months, and then given annual boosters.

Canine Distemper Virus. The canine distemper virus has historically been considered largely insignificant as a felid pathogen. However, recent cases identify canine distemper as a potentially significant pathogen in captive tiger populations (Appel et. al. 1994). At the present time no vaccine is available that has been tested as effective and safe in Panthera species. No commercially produced killed vaccine is currently available. Modified live vaccines carry the risk of inducing the disease in species in which they have not been tested. For the present, the protection of captive felid populations from contact with potential sources of infection, such as dogs and free ranging wildlife capable of carrying the infection, is the most effective method of prevention. If an outbreak of canine distemper occurs or the risk of exposure is very high, then vaccination with highly attentuated avian-origin modified live vaccines such as FrommeD (Solvay Animal Health Inc., Mendota Heights, MN, USA) or FER VAC-D (United Vaccines, Inc., Madison, WI, USA) may be considered but does carry some risk since no clinical trials have been conducted in tigers.

Rabies. The use of rabies vaccines is dependent on local situations. In areas endemic for rabies, a killed vaccine (Imrab, Pitman-Moore, Inc., Washington Crossing, NJ 08560) is recommended for protection of the animal. We realize this recommendation is at odds with the Compendium of Animal Rabies Vaccines, which was prepared by the National Association of State Public Health Veterinarians, but we view it as necessary to protect our patients, particularly in areas where rabies is enzootic in the wildlife. The use of a killed rabies vaccine at the recommended dose (1 ml) produced serum titers, in captive tigers, equivalent to those reported to be protective in domestic species (Bush et al. 1985). This vaccine should be repeated yearly in rabies endemic areas.

Leptospirosis. Leptospirosis is a potential disease in all mammals but has not been reported in tigers. In environments where leptospirosis occurs, vaccination of tigers with a bacterin may be indicated. Two problems arise: first, the correct vaccine serotype may not be available; and second, the duration of protection is usually short lived, 2-3 months.

Feline Leukemia. Vaccination of tigers and other nondomestic felids with feline leukemia vaccine produces good titers. The use of this vaccine as a regular procedure, however, requires more consideration since no tigers have been found to be positive for this virus. Neoplastic and immunosuppression syndromes, as occur in domestic cats with feline leukemia virus, have not been documented in tigers. Vaccination-induced titers could also impair epidemiologic studies in place.

Preventive Dental Care

Sound, regular prophylactic dental care is important in preventing bacteremia of oral origin that can contribute to or promote systemic disease (Fagen 1980a, 1980b). Calculus accumulation should be removed from the tooth surfaces, with care taken to remove material from the subgingival sulcus. If power equipment is available, the scraped surfaces should be polished to smooth dental surfaces, which deters future calculus accumulation. At this time, the subgingival sulcus, gingiva, and teeth should be examined for evidence of gingivitis or periodontal disease. Good nutrition is needed to maintain healthy oral structures. The feeding of bone twice weekly helps promote good gingival health (Haberstroh et al. 1984).

Screening for Parasites and Pathogenic Bacteria

During quarantine tigers are screened for internal parasites by repeated fecal examinations. If present, parasites should be eliminated, with appropriate anthelmintics, before the tiger is released into an exhibit. This is extremely important in naturalistic exhibits (i.e., dirt and grass), which may become contaminated with parasite eggs. These eggs subsequently reinfect the tigers and are extremely difficult to eliminate from the exhibit. Screening for enteric bacterial pathogens should be performed occasionally because salmonella, shigella, and others are shed intermittently.

Parasites

A parasite-monitoring program provides periodic, regular stool examinations to detect parasitic infections. Most internal parasites found in stool examinations are relatively common and ubiquitous in captive situations, with some less frequent infections reported (see Bush et al. 1987). Commonly identified species are from the orders Ascarididae and Strongyloidae (i.e., Toxocara, Toxascaris, Ancylostoma). It is seldom possible to eliminate ascarids totally in the tiger, but they are controllable with periodic administration of oral anthelminthic. These agents can be more effective when the full recommended dosage is given for more than one day, such as three consecutive days, rather than as single treatments. Post-treatment fecal examinations are necessary in assessing efficacy of the initial treatment. Follow-up treatments to remove larval stages not susceptible during the initial treatment may be required. Thorough daily cleaning and disinfection of housing facilities and housing tigers in quarters with sanitizable surfaces will substantially reduce reinfections.

Anthelminthic Programs

In our experience we have found the following anthelminthics effective and safe when administered using appropriate dosage regimens:

Pyrantel pamoate (Strongid-T, Pfizer Inc., New York, NY 10017): 3-5 mg/kg per os. Can be given at this level for 3-5 consecutive days;

Fenbendazole (Panacur, American Hoescht, Somerville, NJ 08876): 5-10 mg/kg per os. Most commonly single day treatment, but can be given three consecutive days at this level; EEP reports 20 mg/kg per day or 100 mg/kg as a one-off dose.

Febantel (Rintal, Miles Inc, Agriculture Division, Shawnee Mission, KS 6201): 6 mg/kg once a day for three days per os. Retreat in two weeks.

Ivermectin (Ivomec, Merck and Co., Rahway, NJ 07065): 0.2 mg/kg, subcutaneous or per os. We have used injectable cattle formulation orally at this dose for 1-3 days. Limited use in tigers with the parenteral route;

Praziquantel (Droncit, Haver-Lockhart, Shawnee, KS 66201): 5.5-6.6 mg/kg. Either as the oral or parenteral form for cestodes;

Sulfadimethoxine (Albon, Roche Chemical Div., Nutley, NJ 07110): 50 mg/kg, parenteral or per os, as a coccidiostat.

Not all eggs or larva observed in fecal examinations may be parasitic to the tiger. The tiger may be serving as a transport host depending on what it has been fed or what feral animals it consumed. Coccidia observed may be associated with feeding whole carcass specimens (e.g., whole rabbits). This emphasizes the need for specific identification of parasite stages seen in stool and an awareness of the tiger's diet.

Pest Control

An obvious need for pest control exists in any animal holding facility. Feral animals serve as sources of additional problems for tigers. Rodents, birds, domestic cats or dogs, or other pests that have access to the tiger or its enclosure may serve as a source of contamination for microorganisms or parasites.

Well-maintained perimeter fencing provides an initial deterrent to the larger feral animals, particularly dogs. However, climbing animals, such as feral cats, can easily defeat such barriers; therefore, areas around tiger enclosures should be monitored regularly for feral animal activity. Live trapping provides a method of removing feral animals acceptable to the public and humane animal interest groups. Local animal shelters usually assist in removal of captured domestic animals. Removal of captured wildlife may be coordinated through state agencies or local rehabilitation groups. Trapping does not provide a total eradication of pests; therefore, the design of the tiger enclosures reduces exposure to feral animals.

Since feral cats are a reoccurring and difficult problem, a potential but untried solution might be to allow a vasectomized male domestic cat (vaccinated and wormed) to establish a territory in the vicinity to rebuke unwanted feral cats (from Jill Mellen, Metro Washington Park Zoo, Portland, OR).

Rodent Pests

Rodent pests must be handled through a well-planned, supervised, continuous pest control program. Safe rodenticides are available for use around tigers when applied according to their directions. Care must be taken in choosing compounds that are effective, yet not highly toxic, especially when considering secondary toxicities. A number of effective anticoagulant rodenticides are available with little or no secondary toxicity potential, e.g., warfarin, diphacinone, cholecalciferol, brodifacoum. These are the backbone of most vermin control programs. When rodent populations become unmanageable or resistant to anticoagulants, other more toxic compounds, such as zinc phosphide may be needed, requiring extra care in their application. It may seem too obvious, but it should be emphasized that at no time should tigers have primary access to any rodenticide. In addition, the program should be designed and instituted to minimize secondary exposure (i.e., consuming rodents that have been feeding on poisonous baits).

Insect Pests

Good sanitation aids in reducing insect populations, but all zoological situations experience insect pests, particularly cockroaches. Insecticide applications can be made around tiger enclosures with chemicals that are safe when applied in a proper manner. There are many chemicals available, both primary insecticides and newer growth regulator compounds, that have low toxicity potential when used correctly. (Examples of insecticides include: diazinon, piperonyl butoxide, natural and synthetic pyrethrins, carbamates, chlorpyrifos; example of growth inhibitor is Gencor.) Tiger enclosures are treated by removing the tigers, applying chemicals safe to use in primary enclosures, and then cleaning the enclosure to avoid exposure to returning tigers. The residual chemicals in cracks and crevices should have no contact with the tigers but, if so, exposure levels should be minimal. All personnel involved with the tigers must participate in the planning stage of the pest control program so everyone is aware of the compounds being used, where and how they are applied, and knowledgeable of the safety of the compounds. Safety of the tigers is utmost in any program.

Inadvertent use or misuse of insecticides (and herbicides and miscellaneous toxic compounds not intended for use around animals) can lead to accidental exposure of tigers and possibly fatal results. One author (L. Phillips) has personally experienced loss of several tigers due to incorrect application of insecticides by inexperienced personnel due to a breakdown in communications. The veterinary staff was not aware that an organophosphate was being used by keepers. Situations like this must be avoided by carefully planned pest control programs and subsequent correct applications of pesticides.

Besides the aesthetic reasons for eliminating pests, a more important reason is eliminating potential diseases found in feral mammals, birds, rodents and insects. The ectoparasites of mammals such as fleas, ticks, and mites, can be transmitted to tigers; as well, internal parasites of these same feral animals can be acquired by tigers and cause infection. Feral animals also serve as potential sources of pathogens such as the feline viral diseases, rabies, yersiniosis, leptospirosis, salmonellosis, toxoplasmosis, feline infectious peritonitis, and others.

Tiger Diseases

Gastrointestinal Diseases

Certain gastrointestinal syndromes have been placed under general categories as "general adaptation syndrome" or "tiger disease" (reviewed in Seidel and Wisser 1987). These problems are historically noted in tigers, especially Siberians. The proposed etiology of "tiger disease" has been reported to be a pancreatic dysfunction (Eulenberger 1981, Straub and Seidel 1983) or disruption of gastrointestinal flora (Kloss and Lang 1976). Stress was documented as the cause in one report which correlated the digestive upsets with sudden changes in the tiger's environment (Cocin et al. 1973). Gastrointestinal upsets should be investigated as being caused by diet, infectious agents (Salmonella spp., Clostridium), or concurrent kidney failure. The specific cause is then treated if identified.

Kidney, Liver and Respiratory Diseases

Kidney, liver and respiratory diseases are recognized problems in aged tigers, and more information is needed (see Bush et al. 1987).

Bacterial Diseases

Tuberculosis, caused by Mycobacterium bovis, has been a major disease problem in tigers in some settings (Michalska 1972). It presents as a chronic non-responsive disease with the lungs as target organs. Localized tuberculous lesions involving the eyes have also been reported (Michalska et al. 1978). Ante-mortem tests are reported to be unreliable. In collections with severe problems, cubs have been vaccinated with BCG starting at four weeks of age, but BCG vaccinations may not be indicated in most situations.

Anthrax has been seen in large felids including tigers (Abdulla et al. 1982). The patient usually dies in 1-4 days. On post-mortem examination there are blood clots reported on the spleen that in the earlier literature were called tumors. Reported treatment includes antisera and antibiotics which have met with limited success. Anthrax is almost always due to feeding contaminated meat (see Chapter 4 for precautions).

Systemic bacterial diseases have been seen in captive tigers such as bacterial meningitis from Klebsiella and Diplococcus (Wallach and Boever 1983). Colisepticemia (Sathyanarayana et al. 1983), Shigella flexneri (Zaki 1980), Salmonella spp. (Kloss and Lang 1976), Corynebacterium pyogenes (Sathyanarayana et al. 1981) and Clostridium perfringens (Pulling 1976) have caused fatal disease in tiger cubs.

Salmonellosis, caused by Salmonella typhimurium, is a recognized medical problem in tigers, occurring either sporadically or as outbreaks (Kloss and Lang 1976). Other species of Salmonella are implicated in enteric disease affecting both young and adult tigers with symptoms ranging from mild gastrointestinal upset to death. To prevent salmonellosis in captive groups of tigers, there must be quality control at the production source, the diet should be maintained frozen prior to feeding, and the thawing process and feeding method must reduce possible contamination (see Chapter 4, Nutrition, Food Preparation and Feeding).

Another source of salmonellosis may be a tiger that is an asymptomatic carrier of Salmonella spp. These tigers serve as sources of infection for others, especially young tigers, and may break with the disease themselves if stressed.

There is a potential for zoonosis with Salmonella spp., as the organisms found in stool cultures from diseased tigers can also cause salmonellosis in humans (Rettig 1983). Potential zoonosis risks can occur with the diseases listed above, such as tuberculosis, rabies and anthrax; therefore it is necessary to take routine preventative precautions when working with a sick tiger.

Viral Diseases

Canine Distemper. (from the editors)Multiple cases of the morbillivirus, canine distemper, as a cause of morbidity and mortality in Panthera tigris and other felid species have now been documented (Appel et al 1994). Historically the canine distemper virus as a cause of chronic encephalomyelitis in a Bengal tiger (P.t. tigris) was reported in 1983 (Blythe et al. 1983). Evidence of a paramyxo-like virus associated with encephalitis in a Siberian tiger (P.t. altaica) was also reported in 1983 (Gould and Fenner 1983). Two adult snow leopards (Panthera uncia) died in 1988 with symptoms of weakness, hemorrhagic feces, seizures, head tilt, ataxia, nasal discharge and dyspnea. Feline panleukopenia virus was confirmed by enzyme-linked immunosorbent assay ante-mortem in one of these leopards. In addition to lesions consistent with feline panleukopenia virus found on necropsy, evidence of interstitial pneumonia was found in both animals. Although virus isolation attempts were negative, canine distemper virus was confirmed in the affected lung of one animal by multiple fluorescent antibody tests. In addition, both snow leopards developed positive serum titers for canine distemper virus during the course of the disease (Fix et al. 1989).

During 1992, canine distemper outbreaks in Panthera species occurred at three geographically separate facilities in the United States. Two leopards (Panthera pardus) died in Illinois with symptoms of depression, anorexia, ataxia and seizures (Dierks). Two tigers at a California facility also developed central nervous system symptoms. One of these cats died and the other recovered with no chronic symptoms. At a separate facility in California, enteric, respiratory and central nervous system symptoms developed in a large group of cats. Seventeen animals died including one jaguar (Panthera onca), four leopards, five tigers, and seven lions (Panthera leo).

Canine distemper virus was isolated from at least one animal at each of the three locations. The isolated viruses were indistinguishable from the naturally occurring type of the virus isolated from dogs and other species. No evidence was found of other concurrent viral infections such as feline immunodeficiency virus which might have predisposed the cats to canine distemper infection. Raccoons (Procyon lotor) were considered the source of the virus in two cases, and dogs were the source in one case (Appel et al. 1994).

During 1993 a large group of privately owned tigers developed symptoms of enteritis, primarily severe diarrhea. This enteritis spread extremely rapidly through this group of cats. Circumstantial evidence indicates that this outbreak may have been due to a primary canine distemper virus infection or a concurrent infection, however canine distemper virus was not isolated.

Rhinotracheitis, Calicivirus, Panleukopenia, Feline Infectious Peritonitis. The upper respiratory viral diseases have been reported in tigers (Von et al. 1981) and have signs similar to those reported in the domestic cat and usually have a high morbidity and low mortality. Treatment is aimed at supportive care.

Panleukopenia has been proven by viral isolation in tigers (Woolf and Swart 1974, Montali et al. 1986) and presents in similar ways to the disease in domestic cats.

Feline infectious peritonitis (FIP) has been confirmed in one Sumatran tiger; it may be an emerging disease problem.

Fungal Diseases

Microsporum canis is not an uncommon cause of hair loss in young tigers (Kloss and Lang 1976, Kymhapeb and Cam 1984). Treatment is similar to that in the domestic cat with equally good results. Griseofulvin is given orally at 20 mg/kg/24 hr, or it can be given weekly at 140 mg/kg. A second cutaneous pathogen, Dermatophilosis cargolensis, has been cultured from skin lesions in polar bears and tigers (Kitchen and Dayhuff 1977). The disease has a chronic course but responds to topical and systemic antibiotics.

Coccidioidomycosis was reported in two Bengal tigers with concurrent liver problems living in endemic areas (Hendrickson and Biberstein 1972).

Nervous System Disorder

Tigers seem prone to central nervous signs with a wide variety of disease conditions (Blythe et al. 1983, Gould and Fenner 1983, Montali et al. 1986).

Congenital Problems

Congenital problems have been reported, and in some instances, may be related to inbreeding (Leipold 1980).

Lacerations and Abscesses

Another potential surgical problem is lacerations from fight wounds. Usually lesions are small and are left to drain and granulate in. It is our procedure to give antibiotics orally for 7-10 days after such fights to minimize local infection and bacteremia that may shower to other organs. A common isolate from the mouths of tigers has been Pasteurella multocida (Woolfrey et al. 1985) with Staphylococcus aureus and Streptococcus viridens as potential problems in tiger bites. Pasteurella multocida usually shows good sensitivity to a wide range of antibiotics with cephalosporins being the drug of choice. Shaving the hair from around all puncture and laceration sites is important to allow drainage and prevent abscess formation.

Abscesses should be clipped and prepped for a sterile culture in order to determine the etiology and guide the choice of antibiotic therapy. The abscess is then opened and drained. Flushing of the lesion with hydrogen peroxide and disinfectant is recommended. The tiger should be treated with systemic broad spectrum antibiotics for 7-10 days. Topical fly repellents applied to these sites will prevent secondary fly larvae infestations.

Dental Fractures

Each tooth is examined, once thoroughly cleaned, for evidence of fractures. Teeth fracture longitudinally or transversely, thus exposing the pulp tissue and periapical structures to infection. The canine teeth are especially prone to fracture or wear because of their location and length. Exposure of the root canal is a common finding in dental fracture or excessive wear. A variety of endodontic procedures provide an option to extraction, which is laborious and disfiguring, especially with canine teeth (Van De Grift 1975, Tinkleman 1979, McDonald 1983). Teeth can be salvaged by performing vital or non-vital pulpotomies and filling the root canals. The remaining crown is left intact. Artificial crowns are not practical and are not recommended. For subgingival fractures, vital and non-vital root retention is applicable. Rotterdam Zoo reports surgical apex resection solved an upper root canal infection in a 19-year-old male Sumatran tiger. Radiological examinations of the teeth and adjacent bony structures are invaluable in determining the extent of disease or trauma and the course of therapy to pursue. Extractions must still be considered with advanced disease. Local dental surgeons can be utilized for consultation as well.

Euthanasia

The euthanasia of tigers is an issue that has become so polarized that it goes beyond the boundaries of whether it is in the best interest of the animal or the best interest of the species. In past years, the euthanasia of tigers suffering severe injury, contagious diseases or other life-threatening ailments was a relatively straight-forward decision by most zoos. That is not the case today. Powerful animal rights lobbyists have sufficiently influenced the general public, many of whom are also the visiting public, to the point that it is now not clear what constitutes an acceptable euthanasia, regardless of the reason, over what is an unacceptable euthanasia. To date there has been no clear resolution of this issue. Each zoo has its own "unstated" position that is influenced by the prevailing political and public relations climate. For that reason, it is difficult to make a consensus recommendation for the euthanasia of tigers.

The AZA has developed a thoughtful policy for the euthanasia of zoo specimens that can be used as a guide in this issue. This policy on euthanasia does not address the removal of surplus SSP animals in order to meet the genetic and demographic goals of these programs (see Chapter 7, Tiger Policies).

A recommendation from the 1992 AAZPA Felid TAG Meeting gives some new direction on this issue (Policy of the Culling [Euthanasia] of Surplus Animals, AAZPA Felid Action Plan, 1991 and 1992). This recommendation was also endorsed by the AAZPA Tiger SSP at the 1992 Annual AAZPA Meeting in Toronto). Beyond this statement, there is no organizational direction from the AZA/WCMC or the AZA Board of Directors for institutions facing this difficult decision.

Necropsy and Pathology

Post-Mortem Examination

Preventive medical programs also depend on the complete post-mortem examination of animals that have died in a zoological collection. This service should provide rapid tentative diagnosis from the gross pathological examination to allow immediate medical care of the remaining collection if indicated. Histopathological examination of tissues is mandatory and should be done in a timely manner to make those findings relevant to the health care of the collection. Concurrent cultures may be indicated for bacteria, fungi, and viruses. Appropriate tissues not formalin fixed may be frozen for viral, toxicology, and genetic studies. Besides determining the cause of death, a complete post-mortem examination allows review of anatomical structure, assessment of nutritional status and parasitic burden of the animal. A copy of the tiger necropsy report should be sent to the AZA Tiger SSP Coordinator, who will then forward copies to researchers analyzing causes of tiger mortality.

Tiger Carcass Disposition

Upon the death of any tiger (Panthera tigris) that is registered in the International Tiger Studbook (Siberian, Sumatran, Indochinese, Bengal, and South China), the following protocol is recommended:

  • Blood samples taken and stored.
  • Carcass put in cooler (do not destroy).
  • Regional Tiger Coordinator contacted for specific instructions regarding tissues and carcass disposition.
  • Report death to the International Studbook Keeper.
  • Owner of the tiger should be notified of the death.
  • Depending on the region and on the condition of the carcass, general disposition routes for the AZA Tiger SSP are
    • Donated to USFWS for their endangered species museum.
    • Hide, skull and skeleton used for zoo education.
    • Hide, skull and skeleton donated to local museum.
    • Skeletal system donated to local university's anatomy department.

Mammary Gland Tumors in Felids

There is considerable concern that some contraceptives (MGA implants and Ovaban) are causing mammary cancer in zoo felids. In order to determine if these contraceptives increase the risks of developing mammary tumors, the types and prevalences of mammary tumors in both contracepted and non-contracepted felids needs to be evaluated. For this evaluation, all available information on any species of felid that has had a mammary tumor, regardless of its contraceptive history needs to be collected. This is an AZA Felid TAG-endorsed study. Your participation will be recognized in any reports or publications resulting from this survey. Please contact the AZA Tiger SSP Coordinator concerning any clinical case or necropsy of a tiger where mammary gland tumors are detected.

Medical Management References

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Appel, M.J.G.; Yates, R.A.; Foley, G.L.; Bernstein, J.J.; Santinelli, S.; Spelman, L.H.; Miller, L.D.; Arp, L.H.; Anderson, M.; Barr, M.; Pearce-Kelling, S.; Summers, B.A. Canine distemper epizootic in lions, tigers and leopards in North America. JOURNAL OF VETERINARY DIAGNOSTIC INVESTIGATION, 1994.Barnett, J.E.F.; Lewis, J.C.M. Medetomidine and detamine anaesthesia in zoo animals and its reversal with atipamezole: A review and update with specific reference to work in British zoos. AMERICAN ASSOCIATION OF ZOO VETERINARIANS ANNUAL PROCEEDINGS. 207-214, 1990.

Blythe, L.L., et al. Chronic encephalomyelitis caused by canine distemper virus in a Bengal tiger. JOURNAL OF THE AMERICAN VETERINARY MEDICAL ASSOCIATION. 183:1159-62, 1983.

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Eulenberger, K. Measurement of creatine concentration in blood serum -- importance to early diagnosis of functional disorders in kidneys of zoo animals, with particular refer- ence to felids. ISEZ. 24:327-35, 1981.

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