Preventive medicine for zoo animals (Proceedings)

The purpose of this presentation is to review the essential elements of a preventive medicine program for captive wild animals. A sound preventive medicine program is the foundation of an animal health program because it is difficult to perform diagnostic tests or treat sick animals successfully; wild animals often mask signs of illness until late into the disease process; and disease outbreaks can have devastating population effects.

Diagnosis and treatment of captive wild animals usually require physical or chemical restraint (including general anesthesia)—procedures that are stressful to healthy animals and may exacerbate an illness or even result in the death of an ill animal. Some bacterial and parasite problems, once established in an exhibit or group of animals, are almost impossible to eradicate and may result in one or more of the following: 1. increased mortality in the animal collection; 2. poor reproductive performance; 3. poor display animals for the visiting public; 4. increased restrictions on shipping animals out of the collection; 5. health risks to surrounding domestic and wild animal populations; and 6. health risks to zoo personnel. The goals of a preventive medicine program, therefore, are: to prevent disease from entering the animal collection; to assure that the animals are properly maintained; and to avoid dissemination of disease to other institutions or to free-ranging populations. The elements of a preventive medicine program include:

• Stock selection

• Quarantine

• Routine health monitoring

• Nutrition

• Enclosure design

• Pest and parasite control

• Husbandry and sanitation

• Minimizing conditions that may result in trauma

• Employee health program

However, before a preventive medicine program can be developed, it is essential that a veterinarian have appropriate training and knowledge in the following areas:

Knowledge in basic veterinary medicine

• Knowledge in principles of medicine, anesthesia, surgery, pathology, diagnostic methods, and treatment procedures

• Knowledge of the most common diseases in thousands of animal species

Knowledge of the various species

• Knowledge of the biology of the different species helps to identify their need for husbandry and nutrition.

• Knowledge about their natural habitat is necessary for the creation of a suitable enclosure to reduce stress and to prevent stereotypical behavior.

• Knowledge about the natural behavior of zoo animals is important to be able to recognize abnormal behavior and development of diseases.

• Knowledge of anatomy and physiology is also important to offer proper husbandry and nutrition, as well as an understanding of a species' susceptibility to certain diseases. It is also necessary for proper diagnostic evaluation and treatment of the patients.

Knowledge in nutritional physiology

• Structure of the diet needed

• Composition of the diet needed

• Absorption and availability of nutrients

Knowledge in reproductive physiology

• Knowledge about breeding cycles is important for the development of breeding programs

• Knowledge about social grouping and proportion of the genders in a social group

• Knowledge of artificial breeding methods

• Knowledge of contraceptive methods

Knowledge in restraint methods

• Proper restraint methods for the various species

• Stress impact of the restraint method on the animal

• Manual restraining methods

• Methods of chemical immobilization

Knowledge of regulations and guidelines

• USDA/APHIS regulations for zoos as a commercial animal care facility

• State regulations for the importation, transportation, and care of wild and zoo animals

• AZA guidelines regarding husbandry standards for zoo animals

Preventive Medicine

Zoo animal collections are dynamic and animals are often shipped between zoos for social or genetic exchange. Therefore, it is very important to evaluate the health status of the collection on a regular basis, and to have proper preshipment and quarantine procedures in place to avoid disease outbreaks.

Preshipment examination

• Blood evaluation (CBC, chemistry, viral and parasitic serology)

• Fecal culture (Salmonella, Campylobacter, Shigella, etc)

• Fecal examination for parasites

• Testing for mycobacteriosis (skin test) in hoofstock, elephants, and primates

• Additional special tests for certain species (brucellosis for hoofstock, Coggin's test for equids, etc.)

• Vaccination(s)

Quarantine procedures

• Duration:

     • For most animals: 30 days

     • For psittacines: up to 60 days

     • For primates: up to 90 days

• Quarantine examination (similar to preshipment examination)

• Vaccination and deworming program

Routine/daily health monitoring

Routine health monitoring of resident animals will make it possible to detect illness earlier, thus increasing the chance for successful treatment and preventing the spread of the disease to other animals. An important aspect of health monitoring is performed by the animal caretakers. They are often the first to detect changes in the animal's behavior or condition that may indicate illness. If possible, animals should be weighed periodically. Unexplained weight loss, even if the animal appears otherwise normal, should be investigated because it may indicate a health problem such as inadequate diet, dental disease, neoplasia, etc.

Routine physical examination

• Recommended for all species (note: there may be a rare exception)

• Generally recommended annually at least every other year, depending on species (note: there may be a few exceptions to this recommendation)

• Similar examination procedures as for preshipment or quarantine

• Should also include: dentistry, radiology, reproductive assessment, etc.

• Collection of normal data on animals

Preventative dentistry

Although the systemic health effects of diet-related oral pathology and the importance of dental health in animals is well documented, only in recent time has dental care of captive wild animals become common. There were many reasons for the lack of dental care in the past. Foremost was the difficulty of restraint and anesthesia, which prevented a thorough examination of the teeth and supporting structures. Thus most dental diseases went undetected and untreated until swelling or clinical signs (anorexia, dropping food, etc.) became obvious. When dental problems were found, the lack of available dental expertise often led to incomplete treatment or to needless tooth extractions. Another reason for poor dental health in captive mammals was the sparse knowledge of proper nutritional and functional diets. Too often, the cheapest and the most readily available foods were used, however inappropriately. Fortunately, many zoos have now added nutritionists to their staff.

Vaccinations

The specific vaccination program for each animal facility should be designed by the consulting veterinarian based on the following: 1. the types of animals present; 2. the history of infectious disease problems in the species or the facility; 3. the potential risks versus benefits of each type of vaccine; 4. the latest information on the disease susceptibility of various species; 5. the safety and efficacy of the available vaccines; and 6. recommended vaccination intervals. Other considerations in developing a vaccination program include:

• Depends on history of health status and vaccination of zoo animals

• Depends on Federal and State regulations

• Depends on regional endemic pressure

• Controversial:

     • Need for certain vaccines:

          • Rabies in species other than carnivores

          • Certain human vaccines for primates: question of exposure

          • Canine distemper for large felids

     • Vaccine product:

          • Not approved for species other than on label

          • Only few research data available regarding efficacy or side effects of certain vaccine products

     • Vaccination interval:

          • Questionable efficacy for longer interval

          • Questionable side effects for shorter interval (fibrosarcoma, encephalopathies)

Pregnancy checks

• Urine and fecal hormone analysis

• Physical examination with assessment of reproductive organs

• Ultrasound

• Radiology

• Thermography

Baby wellness checks

• Depending on the species and its social structure

• Within the first few days after birth, if possible

• Physical examinations

     • Normal development

     • Hydration and nursing status

     • Urination and defecation

     • Protein and electrolytes via blood collection, if necessary

• Vaccination

• Hand-raising should only be considered when neonate is orphaned, abandoned by the mother, or the raising of multiple neonates together facilitates care and ensures normal social development.

Husbandry and nutrition

• A zoo veterinarian has to evaluate and approve husbandry and assist in developing nutrition programs for each species within a collection.

Personnel health program

• A well-defined personnel health policy is also an important part of a preventive health program. Several infectious diseases of humans, such as tuberculosis, measles, and amoebic dysentery, can be acquired by captive wild mammals, especially primates. Preemployment screening and proper training, plus periodic tuberculin testing and health monitoring during employment, will minimize the potential for disease transmission from caretakers to animals.

Summary

A comprehensive preventive medicine program for any collection of captive wild animals should be the foundation of the animal health program at any animal facility. Once a wild animal becomes ill, it can be very difficult to perform diagnostic tests or to treat it successfully. Signs of illness in a captive wild animal may not become obvious until the animal is in extremely poor health. Any short-term inconveniences caused by practicing sound preventive medicine are more than offset by the improved health of the animals, reduced economic losses, and increased safety for the animal caretakers.

References

Fowler, ME. Zoo and Wild Animal Medicine. 2nd ed. WB Saunders, Philadelphia. 1986.

Fowler, ME, and RE Miller. Zoo and Wild Animal Medicine. Current Therapy 4. 4th ed. WB Saunders, Philadelphia. 1999.

Fowler, ME, and RE Miller. Zoo and Wild Animal Medicine. 5th ed. WB Saunders, Philadelphia. 2003.

Hinshaw, KC, WB Amand, and CL Tinkelman. Preventive Medicine. In: Kleiman, DG, et al. (eds). Wild Mammals in Captivity. Chicago: University of Chicago Press, 1996;16-24.

Junge, RE. Preventive medicine recommendations. In: Infectious Disease Notebook. Philadelphia: American Association of Zoo Veterinarians, 1993.