The Truth about Cats and Hog Farms

Livestock Update, August 2004

Allen Harper, Extension Animal Scientist ­ Swine, VA Tech Tidewater AREC

As a middle aged Extension Swine Specialist who is secure in his masculinity, I can freely admit that my family owns three cats. All three were poor homeless wretches taken in by my tender hearted wife. Aside from reaching old age, all three are in a fine state of health; the female is spayed and both males are neutered. The most recent addition, ole Nip, came in as a 3-day old orphaned kitten and was bottle fed until weaning. Now Nip actually resides in the house. This is something that I never would have considered in my younger, more macho days. But what about cats on hog farms. This is where professional integrity requires that I draw the line. With what is known about cats, rodent control and food safety, it can never be recommended that cats be allowed to reside on the hog farm. Here's why.

Cats and Rodent Control. There seems to be a general assumption that barn cats are very helpful in controlling mice and rats on hog farms. This is a myth that probably originated with the suppositions and practices of earlier generation farmers and continues as popular theory today. It is certainly true that a barn cat can be seen occasionally with a lifeless mouse, or perhaps even a rat, dangling from its jaws. The natural assumption then is that if the cat is seen killing a rodent at a random point in time, it is probably working around the clock and keeping the farm rodent population in check. However, wildlife and rodent control experts indicate that cats do not provide effective rodent control in the majority of cases (see Pork Industry Fact Sheet 107). Indeed mouse and rat colonies can be found living in hog farm buildings in close association with barn cats. The only truly effective means to reduce and control mouse and rat problems on hog farms involves debris removal, excellent sanitation, proper feed storage and handling, and routine use of bait stations with approved rodenticides.

The Feral Cat Problem. Feral cats are so-called "wild" offspring of domestic cats. According to Linda Kelson of the Feral Cat Coalition, the feral cat population in the U.S. is estimated to be approximately 60 million. The magnitude of such a problem has obvious implications related to animal welfare, reservoirs for rabies and other feline diseases and excess predation on wildlife species. If there was ever an argument for spaying and neutering domestic cats, the feral cat problem is it.

There is really no hard science indicating that barn cats are components of the feral cat problem. But it is highly likely that they are contributors. Cats are exceptionally prolific. Intact male and female barn cats allowed to roam freely will undoubtedly interbreed with feral cats and vice-versa. The problem expands exponentially because the offspring of these matings reach breeding age rapidly and reproduction of subsequent generations is very rapid.

Food Safety Concerns. Toxoplasma gondii is a protozoan parasite that can be found in muscle and other tissue of many warm-blooded animals. Included among these species are pigs and humans. As reported on behalf of the National Pork Board by researchers Ray Gamble and Sharon Patton, people can become infected if they consume raw or extremely undercooked meat that is contaminated with microscopic tissue cysts containing Toxoplasma gondii. In adults with healthy immune systems the consequences of "toxoplasmosis" are usually minor such as temporary flu-like symptoms until immunity develops. But a major health risk exists for people with compromised immune systems and for pregnant woman. In the case of pregnant women, an active toxoplasmosis infection can be transferred across the placenta with potentially serious health consequences for the developing fetus.

National testing programs indicate that the presence of Toxoplasma gondii in pigs in the United States has declined since the 1980's and the incidence in pigs currently is low. Nevertheless the importance of food safety requires that producers strive to continue to reduce the potential for Toxoplasma presence in pig tissues. Cats are considered a definitive host for Toxoplasma gondii because felines are the only species in which the organism can complete its life cycle. Infected cats excrete oocysts in feces that are viable and infective. If such fecal matter is consumed in any way by pigs or other warm blooded species, the animal can become contaminated. These facts make cats an important reservoir and potential vector of Toxoplasmosis on hog farms. Quite frankly, any benefits that barn cats provide by way of minor rodent control or personal entertainment is more than off-set by the even remote potential for Toxoplasma transfer in pork products.

Visit Virginia Cooperative Extension