Abstract

Resident wildlife populations present a threat to captive animal collections through predation, competition for food, and serving as a source of infectious disease. Many facilities employ a protocol for trapping and euthanasia to reduce these populations; however, this process often creates a vacuum allowing new animals to move into the territory at a faster rate. The Columbus Zoo and Aquarium employed a trap-and-euthanatize protocol for several years, and animals that were euthanatized were submitted for necropsy to the Ohio Department of Agriculture. A review of the pathology reports over the past 4 yr revealed an average of 115 animals submitted per year. None of the animals submitted during this time period were diagnosed with rabies or distemper.

A preventive health program was implemented at the Columbus Zoo and Aquarium for resident wildlife frequently trapped. The raccoon, (Procyon lotor), is a common inhabitant of the zoo grounds and was selected as a trial species for this program. This carnivore often enters animal housing areas and raids food supplies or predates the captive collection, while also contaminating the area with urine, feces, and saliva. In order to reduce the risk to both the animal collection and the human workers that potentially encounter contaminated material and/or raccoons, a protocol was developed to address viral and parasitologic risks.

Live traps were set strategically around zoo grounds and keepers checked traps every morning. Once a raccoon was captured, it was transported to the hospital for processing. Each animal was immobilized, weighed, and a physical exam was performed. Blood was collected for serology and serum banking, and a fecal sample was evaluated for parasites. Surgical sterilization was performed, (males were vasectomized, females had tubal ligations performed), and each animal was permanently identified with a microchip and metal ear tag. Vaccinations included rabies, canine distemper combination including leptospirosis, and feline parvovirus were administered. A long-acting anthelmintic, (moxidectin, ProHeart 6, Fort Dodge Animal Health, Overland Park, KS, USA), was given, and topical flea and tick preventive, (fipronil, Frontline, Merial United States, Athens, GA, USA), applied. Raccoons were then recovered in crates and released at the trap site in the evening. In the event a raccoon was re-trapped within 1 mo, it was released immediately. Any animal trapped 30 days beyond initial examination was re-immobilized for venipuncture, fecal collection, and repeated vaccinations/de-wormer if necessary.

This program has been in place for almost 2 yr, and data collected indicates that there is a relatively static population of raccoons on and around the zoo grounds. Thirty-one animals were trapped and processed in 20 mo. Twenty-two of those animals were re-trapped, and most were repeatedly re-trapped. Trapping procedures and frequency have not been altered in 6 yr. These results indicate populations of resident raccoons have established home ranges that include zoo property. The significant decrease in number of raccoons trapped from prior to initiation of program to present may be due to territorial defense, which would slow the vacuum effect of trap-and-removal protocols. Establishing a ‘protected’ population of raccoons on grounds also potentially reduces the risk of exposure to infectious diseases to both collection animals and human workers.