Certain bacteria may cause gastrointestinal disease in cats. The most common of these are discussed below.

Campylobacter Infection

Gastrointestinal campylobacteriosis is a bacterial disease. It is caused by 2 related bacteria of the Campylobacter genus. These 2 organisms, along with a number of other species of Campylobacter, can be isolated from carrier cats (those that do not show signs) as well as ill cats. Cats, especially those recently obtained from shelters, can serve as sources of human infection.

Exposure to feces of infected animals and food- or waterborne transmission appears to be the most common routes of infection. One suspected source of infection for pets is eating undercooked poultry and other raw meat products. Wild birds also may be important sources of water contamination.

The diarrhea appears to be most severe in young cats. Typical signs include mucus-laden, watery, or bile-streaked diarrhea (with or without blood) that lasts 3 to 7 days; reduced appetite; and occasional vomiting. Fever may also be present. Intermittent diarrhea may persist for more than 2 weeks; in some, it may last for months. To diagnose campylobacteriosis, a veterinarian will test the animal's feces and blood for evidence of infection.

Antibiotic treatment for cats found to carry these bacteria is usually reserved for those that are young, severely affected, or a potential source of human infection. This is because other organisms are likely to be involved and antibiotic treatment is often not effective.

Salmonella Infection

Many species of Salmonella bacteria can cause gastrointestinal illness. A Salmonella infection can cause severe blood poisoning (septicemia) or inflammation of the intestine. The disease occurs in all domestic animals, as well as humans, but it is infrequent in cats. Infected cats may become carriers of Salmonella but often do not show any signs of disease.

Signs of disease are more likely to occur during hospitalization, in cats with another infection or debilitating condition, or in kittens exposed to large numbers of the bacteria. Signs include sudden diarrhea with blood poisoning. Pneumonia and conjunctivitis (inflammation of eye membranes) are sometimes present. Diagnosis is based on signs of disease and on the laboratory examination of feces.

Early treatment is essential for blood poisoning. In many cases, antibiotics are given intravenously. Fluids may be given intravenously as well. The intestinal form of the disease is difficult to treat effectively. Antibiotics are not always recommended, due to concerns about the development of antibiotic-resistant bacteria. Although the signs of disease may disappear, eliminating the bacteria from the body is difficult, particularly in adult cats.

Tyzzer's Disease

Tyzzer's disease is an infection caused by the bacterium Clostridium piliforme. It affects a wide range of animals but is rare in cats. It most often affects young, healthy animals that have been subjected to stress or other diseases (such as feline infectious peritonitis). The bacteria primarily affect cells in the intestine, liver, and heart.

Signs vary, but may include decreased activity, loss of appetite, fever, jaundice, and diarrhea. Before death, there are convulsions and coma. A diagnosis of Tyzzer's disease is based on laboratory examination of tissue sections for the presence of the bacteria.

Little is known about the effectiveness of antibiotics for treatment. Some antibiotics may aggravate the disease. Cats suspected of being infected may be treated with intravenous fluids and appropriate antibiotics.

Last full review/revision July 2011 by Dana G. Allen, DVM, MSc, DACVIM; Sharon Campbell, DVM, MS, DACVIM; Ben H. Colmery, DVM, DAVDC; James G. Fox, DVM, MS, DACLAM; Carlton L. Gyles, DVM, PhD, FCAHS; Walter Ingwersen, DVM, DVSc, DACVIM; Lisa E. Moore, DVM, DACVIM; Sofie Muylle, DVM, PhD; Sharon Patton, MS, PhD; Andrew S. Peregrine, BVMS, PhD, DVM, DEVPC; Stanley I. Rubin, DVM, MS, DACVIM; H. Carolien Rutgers, DVM, MS, DACVIM, DECVIM-CA, DSAM, MRCVS; Jörg M. Steiner, DrMedVet, PhD, DACVIM, DECVIM-CA; Thomas W. Swerczek, DVM, PhD