Salmonella FAQs

Horse Stall
New horses introduced to a barn should be isolated for approximately 2-3 weeks to minimize the chance of disease to be spread.

Call your veterinarian or contact the UF Large Animal Hospital at (352) 392-2229 if you suspect that your horse may be infected with Salmonella.

What is Salmonella?

Salmonella is a type of bacteria that can cause intestinal disease (such as diarrhea) in horses, cattle, sheep, goats, llamas, dogs, cats, birds, humans, and many other species.

Can horses have Salmonella and not be sick?

Yes. Published studies have found that around 1 out of 100 healthy horses shed Salmonella bacteria in their manure. Among the subset of horses admitted to equine hospitals, the likelihood of shedding is higher – an estimated 1 in 10 of these horses are positive. It is possible that a horse with Salmonella in its feces may show signs of infection if the organisms multiply and increase in number. This “overgrowth” can occur during times of stress, such as during transportation, illness, and hospitalization.

Can people be infected with Salmonella from animals?

Yes. In theory, any person is at risk. Though it is not a high risk in healthy people, they can be infected and become sick. Young children and immune compromised people may be more likely to become ill if infected with Salmonella and are at greater risk of significant complications. Therefore, it is essential to prevent them from being exposed to animals with Salmonella. If you have questions about your particular level of risk, please consult your physician for additional advice.

How do horses get Salmonella?

Horses may acquire the bacteria from other horses or other animals. Transmission is by the fecal-oral route, which means manure from one animal (not necessarily a horse) was ingested by another – this usually happens when the manure contaminates a feed or water source. Horses may pick up Salmonella from the pasture, feed, or water sources when the feces of other animals (including birds and other horses) contaminate these sources.

What are the signs of Salmonella in horses?

  • Diarrhea (most common symptom) – which can range from “cow-pie” manure to “watery” diarrhea
  • Colic – especially prior to the onset of active diarrhea
  • Shock – usually caused by dehydration

Occasionally Salmonella can get into the blood stream and go to many different organs, including the liver, lungs, joints, and others – this is particular risk in young animals. In chronic cases, horses may have weight loss or intermittent mild colic signs. Salmonella can cause several problems and clinical signs. If you have questions regarding these signs, please contact your veterinarian.

What are the signs of Salmonella in other animals, including humans?

Signs of Salmonella in other animals and humans vary from being apparently normal to severe gastrointestinal disease, such as abdominal pain, diarrhea, vomiting, and cramps. Consult your veterinarian or physician if these signs are present.

How is Salmonella diagnosed?

The most common diagnostic test is culture of a manure sample. Blood and other tissues can also be sampled. Culture results take two to five days when the sample is received at the laboratory. Fecal cultures can be negative in horses with salmonellosis, but it has been shown that cultivating multiple samples increases the probability of finding Salmonella when it is present. The usual protocol is twice per day for a total of five cultures.

What is the treatment for Salmonellosis?

Treatment varies with the severity of salmonellosis, ranging from no treatment to intensive medical care. Treatment may include intravenous fluid therapy, antibiotics, non-steroidal anti-inflammatory drugs and plasma. These medications are important to replace fluid losses due to diarrhea, control the effects of the infection, and manage signs of shock.

What is the prognosis of Salmonella?

The prognosis varies with the case. Many horses may have Salmonella and never show clinical signs. Others can become sick and require intensive therapy. Some sick horses may die suddenly despite intensive therapy.

Should I have an Infection Control Program on my farm?

Yes. While a farm program need not to be as extensive as in a hospital, some method of isolating new arrivals and sick horses is advisable. New horses introduced to a barn should be isolated for approximately two to three weeks to minimize the chance of disease to be spread. This time allows monitoring of the new horse for diarrhea or signs of respiratory disease. Horses that have newly arrived at a farm, even if they are isolated correctly, may still have Salmonella in their intestine and may later shed it if stressed.

Dr. Martha Mallicote

Information provided by Dr. Martha Mallicote, Veterinarian of UF Large Animal Internal Medicine, Clinical Associate Professor, DACVIM

University of Florida


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