MANAGEMENT
PIH-107
Pork Industry Handbook
PURDUE UNIVERSITY COOPERATIVE EXTENSION SERVICE • WEST LAFAYETTE, INDIANA
Controlling Rats and Mice in Swine Facilities
Authors:
Robert M. Timm, University of Nebraska
Rex E. Marsh, University of California
Robert M. Corrigan, Purdue University
Ken Holscher, Iowa State University
Reviewers:
Bob and Diane Bell, Camden, Arkansas
Peter T. Bromley, Virginia Polytechnic Institute and State University
William Fitzwater, Albuquerque, New Mexico
Mike and Debbie Nichols, Oakfield, Tennessee
Rats and mice can be a major economic threat around swine facilities. They consume and contaminate feed and cause feed losses through the gnawing of holes in feed sacks and wooden bins. They may also be responsible for maintaining or spreading swine diseases.
House mice (Mus musculus), Norway rats (Rattus nor-vegicus), and roof rats (Rattus rattus) as a group are considered the most troublesome and economically important rodents in the United States. These non-native “commensal” rodents live under a variety of urban and rural conditions. They may thrive in and around farms and rural homes and in some situations inhabit open fields and agricultural crops.

Norway rats will undermine building foundations and concrete slabs. Roof rats and house mice, in addition to Norway rats, are particularly destructive to building insulation. Most common types of insulation including rigid foam and fiberglass are susceptible to rodent damage. A rodent infestation can damage structures by thousands of dollars in a matter of months. Additionally, rodents may gnaw on electrical wiring causing equipment malfunction, power outages, and potentially dangerous short circuits.

Norway rats and house mice are found in all of the contiguous 48 states, although the Norway rat may be absent from some relatively large geographic areas of the West. The roof rat primarily occupies the coastal areas of Washington, Oregon, and California, as well as a larger area along the Gulf and Atlantic coast states from Texas to Maryland. In general, the roof rat is considerably less important to the pork producer.

Rodents and Swine Diseases
Rodents and other wildlife can be significant in the transmission of swine diseases. The actual occurrence of such diseases in rodents, and the degree to which they con-
tribute to disease problems on hog farms, is poorly documented.

Table 1 lists swine diseases that rats and mice may harbor or disseminate. Rodents, like other wild animals, insects, and people, are capable of carrying diseases directly into a swine facility upon their entry. Rodents can spread or accelerate the spread of established diseases from contaminated areas to uncontaminated areas via their droppings, feet, fur, urine, saliva, or blood. As an example, Norway rats may travel through infected feces of isolated sick pigs and then contaminate the food and water of healthy animals some several hundred feet away.

Additionally, rodents around farm buildings are a food source that may attract wild predatory animals such as foxes, coyotes, raccoons, and skunks, which in turn may contribute to disease problems. Rodents may also attract stray dogs and cats which can transmit still other diseases. An effective disease barrier system cannot be achieved or maintained without good rodent control.
Table 1. Diseases of swine in North America that rodents may harbor or disseminate.
		Rodents
Disease	Agent	implicated
Bordetellosis	bacteria	rats
Encephalomyocarditis	virus	rats, mice
Leptospirosis	bacteria	rats, mice
Pseudorabies	virus	rats*
Salmonellosis	bacteria	rats, mice
Swine dysentery	bacteria	rats, mice
Swine erysipelas	bacteria	rats
Toxoplasmosis	protozoan	various rodents
Trichinosis	nematode	rats
* Opinions differ on the significance of rodents as the reservoir		or disseminator.
		
Cooperative Extension work in Agriculture and Home Economics, state of Indiana, Purdue University and U. S. Department of Agriculture cooperating. H. A. Wadsworth, Director, West Lafayette, IN. Issued in furtherance of the acts of May 8 and June 30, 1914. The Purdue University Cooperative Extension Service is an affirmative action/equal opportunity institution.