Vet Column 3-22-10
March 22, 2010
Most livestock producers have at some time heard about the wild pig population, sometimes called feral pigs. Often the reports are noted in passing, interesting, but soon forgotten since it was another State or someone else’s issue. A recent publication, however, from the University of California-Davis and the University of Alberta presents some data that reemphasize the importance of this issue for all livestock producers.
Pigs were not native to the United States and were initially introduced to the mainland by European settlers hundreds of years ago. In California, the Spanish were the first to release domestic pigs in 1769. In the 1920s, a county landowner in California introduced the European wild boar onto his ranch in Monterey County for sport hunting. Since then, many illegal releases of boar within the state have occurred to create further hunting opportunities.
Today, wild pigs are hybrid crosses of escaped feral domestic pigs and wild boar and are regulated as game animals by the State of California. Presently, wild pigs exist in 35 States and in 56 of 58 counties in California. Other recent reports have pegged the estimated number of wild pigs in Texas alone at over 2 million animals.
Wild pigs are able to reproduce year-round, producing 10 to 12 piglets per year. Once they become established in the environment, they are difficult to eradicate. Because of their foraging behaviors, they are capable of destroying large areas of natural habitat. As the California rural-urban interface grows, not different in principle than many other locations, wild pigs come into increased contact with agricultural systems. It is estimated that 4 million wild pigs nationally cause annual damage totaling $1 billion.
Wild pigs are susceptible to a variety of viral and bacterial diseases. These diseases include classical swine fever, otherwise known as hog cholera, vesicular stomatitis, brucellosis, pseudorabies, bovine tuberculosis, and foot-and-mouth disease. Many of these diseases are transmissible to humans and livestock as well as other wildlife. Additionally, there is concern that should a disease such as foot-and-mouth disease emerge in wild pig populations, it may become a disease reservoir resulting in the disease becoming endemic in wildlife.
From a food safety concern, it is widely accepted that wild pigs were one of the possible sources for the E. coli O157:H7 outbreak in September 2006 in California. This outbreak was traced to the consumption of spinach grown in San Benito or Monterey counties. Even though wild pigs may have been the culprit, the difficulty in proving the source resulted in the implication of domestic cattle as a potential source as well, fairly or not fairly.
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Livestock producers may not be raising or having anything to do with swine. This recent article, however, points out the importance that all livestock producers are connected, often in subtle ways. Much like the Texas cattle fever issue in south Texas, even though located miles from most other cattle producers, the issue if not controlled can spread rapidly and affect other cattle raisers. As with this example of wild pigs, if they are in 35 States already, they have the potential to affect market opportunities for many other unsuspecting livestock producers.