Visit with a Vet: Feral Swine -- More Than Just a Nuisance

Originally published in the Dec. 25, 2013, issue

 

 

Visit with a Georgia veterinarian in this monthly feature. This edition comes from State Veterinarian Dr. Robert Cobb in Atlanta, Ga.

Free-ranging populations of wild pigs, or feral swine, exist in at least 39 states. Some estimate their numbers to be more than 4 million, with the largest populations located in California, Florida, Hawaii and Texas. Georgia’s large population of feral swine resides mostly in the river swamps of south Georgia, but can be found statewide.

Today’s feral swine population is a combination of escaped or neglected domestic swine, Eurasian wild boar and feral pigs that have been captured and transported for the purpose of starting wild, free-living populations. The intentional movement of trapped feral swine resulted in extensive crossbreeding of feral populations, producing many variations.

Feral swine regularly tear through livestock and game fences; consume animal feed; destroy field crops such as corn, milo, watermelon, peanuts, hay, turf and wheat; and, when given the opportunity, will prey upon young livestock and other small animals.

Moving untested feral swine to new areas or allowing them onto farms with domestic pigs is illegal in Georgia and can have disastrous consequences to the commercial swine industry. Feral swine can be imported into Georgia only by a special permit issued by the state veterinarian. Three feral swine agreements are utilized by the Department in cooperation with the US Department of Agriculture. Individuals wishing to have feral swine facilities must meet strict testing, fencing and reproduction prevention protocols. The feral swine facilities are regularly inspected by the Department to assure compliance with the rules in order to maintain separation of feral swine from domestic herds.

Feral swine are carriers of a number of diseases: swine brucellosis, pseudorabies, leptospirosis, tuberculosis, tularemia, trichinosis, plague, anthrax, African swine fever, classical swine fever  or hog cholera and swine vesicular disease. USDA eradicated hog cholera from the US in 1976.

Though they’ve been eliminated or controlled from US commercial production swine herds, some are still found in Georgia feral swine and can be readily transmitted to humans and other animals:

Brucellosis is a bacterial infectious disease of animals and humans, caused by Brucella bacteria. Swine brucellosis is a reproductive disease, causing abortions in sows and infertility in boars. Infected swine are disease carriers for life and can serve as sources of infection. The only way to remove the disease is to detect infected swine through blood tests and cull the animals. In humans, the disease may mimic severe flu and may cause crippling arthritis or meningitis. Animals and humans are exposed to the swine Brucella bacterium by contact with infected blood, reproductive tissues and fluids from animals during farrowing, abortion or carcass dressing.

Pseudorabies: Viral PRV attacks the central nervous system and is fatal to cattle, horses, goats, sheep, dogs, cats, raccoons, skunks, opossums and small rodents. Though not fatal in swine, it causes abortions and stillbirths. Pseudorabies is caused by a herpesvirus in swine. It is not related to rabies and it does not infect humans. The spread of PRV from feral swine to domestic cattle has also been documented in Florida and Texas. Feral swine are known to break into feed bunks and congregate around areas where supplemental feed is distributed, providing a source of contamination of feed and potential spread of infection through contact with domestic herds.

Parasites: Feral swine are also host to several disease-causing parasites. These parasites include lung worm, kidney worm, thorny-headed worm, ascarid roundworm, hog lice and the parasite that causes trichinosis.

The more feral swine populations increase and expand, the greater the chances that they may transmit diseases to domestic animals, wildlife and humans as well as destroy expensive crops. To minimize the threat feral swine pose to domestic swine operations, farmers should not introduce wild pigs into herds or attempt to market wild-caught pigs. Before transporting breeding swine, perform blood tests according to state and federal guidelines, and blood-test all new stock before adding them to existing herds. Fence out feral swine and do not butcher feral swine on the farm, or feed offal from field-dressed wild hogs to domestic ones.