Feral Swine Disease Risks to Cattle 

Why should I worry about feral swine? 

Animal and Plant Health Inspection Service

Feral swine destroy feed crops, damage fences, and contaminate water 

sources but their greatest threat to domestic cattle is disease transmission. Feral 

swine can carry many bacterial, viral, and parasitic diseases of concern for 

cattle. Infection occurs through direct contact with feral swine that use pastures 

or feedlots with cattle. Transmission also occurs indirectly if feral swine are able 

to access feed and water sources utilized by cattle

Feral Swine Disease and Cattle Production

Many of the pathogens and parasites carried by feral swine can cause weight loss, 

abortions, infertility, or death in cattle. A positive test for some diseases, even 

without clinical symptoms, can require quarantine of cattle causing production 

losses, reduced access to markets, and can even require disposal of animal 

products. Some diseases, such as brucellosis, are caused by different strains of the 

same species of bacteria. Feral swine typically carry Brucella suis, this strain 

generally does not cause symptoms in cattle, however it can cause positive tests. 

Other strains of the Brucella bacteria will cause clinical illness in cattle. 

Disease Routes of Transmission Symptoms in Cattle 

Brucellosis (Brucella 

species bacteria) 

Direct contact with infected animals, aborted 

fetuses, afterbirth, or vaginal discharges. 

Ingestion of contaminated feed or water. 

No clinical signs of Brucella suis infection, but can cause 

positive milk ring test (a routine test for dairy farms.) 

Other Brucella strains cause abortion and infertility. 

Leptospirosis Direct or indirect contact with infected urine. Fever, anemia, lethargy, jaundice, abortion, and infertility. 

Pathogenic E. coli Ingestion of contaminated feces, food,

or water. 

Diarrhea, lethargy, loss of appetite, and fever; although

most cattle show no signs of infection, transmission to 

humans is a public health risk. 

Pseudorabies (Aujeszky’s 

disease or “mad itch”) 

Nose-to-nose contact, contaminated water or

feed, ingestion of infected tissues, aerosol, or 

contaminated equipment. 

Intense itching, weakness, convulsions, rapid breathing, 

and death. 

Salmonellosis Ingestion of contaminated feces, food or 

water. 

Severe watery, occasionally bloody, diarrhea, decreased 

milk production, dehydration, increased salivation, and 

fever. 

Tuberculosis Contact with infected animals, indirect 

contact with contaminated feed or water. 

Uncommon outside of Hawaii. 

Loss of body condition (wasting), lethargy, fever, chronic 

cough, death. 

Diseases of concern for cattle production
Feral Swine Disease Risks to Cattle 

Want to learn more?

Call Wildlife Services, a program within the U.S. Department of Agriculture’s (USDA) 

Animal and Plant Health Inspection Service, at 1-866-4-USDA-WS or visit 

www.aphis.usda.gov/wildlife-damage/stopferalswine 

to learn more about the problems caused by this invasive animal, 

as well as to seek advice and assistance in dealing with feral swine.

Take additional precautions to prevent contact between feral swine and cattle if feral swine are found in 

your area. See the map to determine where feral swine currently exist.

Store cattle feed in barns or prevent feral 

swine from accessing feed whenever possible.

Avoid feeding in troughs or on the ground, this 

can cause an increased risk of pathogen 

transmission since feral swine can access the 

feed easily.

Prevent feral swine access to water sources 

used by cattle. 

What is at risk? 

How can I protect my cattle from becoming

infected?

The beef and dairy industries are invaluable; contributing more than $100 billion to the United States 

economy annually and feeding millions. With expanding feral swine populations overlapping with beef and 

dairy farms it becomes increasingly important to protect your livestock

from exposure to feral swine disease risks. Disease introductions from 

feral swine could have a huge financial impact through losses in 

productivity, decreased product quality, as well as potentially 

detrimental impacts on trade.

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