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Feline Infectious Peritonitis

By Otto M. Radostits, CM, DVM, MSc, DACVIM (Deceased), Professor Emeritus, Department of Large Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan ; Max J. Appel, DMV, PhD, Professor Emeritus ; David A. Ashford, DVM, MPH, DSc, Assistant Area Director, International Services, APHIS, USDA ; Stephen C. Barr, BVSc, MVS, PhD, DACVIM, Professor of Medicine, Department of Clinical Sciences, College of Veterinary Medicine, Cornell University ; J. P. Dubey, MVSc, PhD, Microbiologist, Animal Parasitic Diseases Laboratory, Beltsville Agricultural Research Center, USDA ; Paul Ettestad, DVM, MS, State Public Health Veterinarian, Epidemiology and Response Division, New Mexico Department of Health ; Craig E. Greene, DVM, MS, Professor, Department of Small Animal Medicine, College of Veterinary Medicine, University of Georgia ; Delores E. Hill, PhD, Parasitologist, U.S. Department of Agriculture ; Johnny D. Hoskins, DVM, PhD, Small Animal Consultant ; Eugene D. Janzen, DVM, MVS, Professor, Production Animal Health, Faculty of Veterinary Medicine, University of Calgary ; Jodie Low Choy, BVSc, BVMS, IVAS Cert, Menzies School of Health Research; University Avenue Veterinary Hospital, Northern Territory, Australia ; Dennis W. Macy, MS, DACVIM, Professor of Medicine and Oncology, College of Veterinary Medicine and Biomedical Sciences,Colorado State University ; Dudley L. McCaw, DVM, DACVIM (Small Animal, Oncology), Professor, Department of Clinical Sciences, College of Veterinary Medicine, Kansas State University ; Barton W. Rohrbach, VMD, MPH, DACVPM, Associate Professor, Department of Comparative Medicine, Veterinary Teaching Hospital, University of Tennessee ; J. Glenn Songer, PhD, Professor, Department of Veterinary Science and Microbiology, University of Arizona ; Richard A. Squires, BVSc (Hons), PhD, DVR, DACVIM, DECVIM-CA, GCertEd, MRCVS, Head of Veterinary Clinical Sciences, School of Veterinary and Biomedical Sciences, James Cook University ; Bert E. Stromberg, PhD, Professor, Veterinary and Biomedical Sciences, College of Veterinary Medicine, University of Minnesota ; Joseph Taboada, DVM, DACVIM, Professor and Associate Dean, Office of Student and Academic Affairs, School of Veterinary Medicine, Louisiana State University ; Charles O. Thoen, DVM, PhD, Professor, Veterinary Microbiology and Preventive Medicine, College of Veterinary Medicine, Iowa State University ; John F. Timoney, MVB, PhD, Dsc, MRCVS, Keeneland Chair of Infectious Diseases, Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky ; Ian Tizard, BVMS, PhD, DACVM, University Distinguished Professor of Immunology; Director, Richard M. Schubot Exotic Bird Health Center, Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University

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Feline infectious peritonitis is caused by a feline coronavirus. Coronaviruses are a family of viruses that chiefly cause respiratory infections. The disease is seen worldwide. Although a large number of cats may be infected with the feline coronavirus, only a few show signs of disease. Cats of all ages and either sex can develop feline infectious peritonitis, but the disease is most frequent in cats 6 months to 2 years old. Kittens raised in infected colonies may contract the virus from their mothers or from carriers (infected cats with no obvious signs of disease) when their maternal immunity decreases at 5 to 10 weeks of age.

Most infections probably result from ingestion of the virus. Transmission by inhalation is also possible. Because cats shed particles of the virus in feces, litter box exposure and mutual grooming are important sources of infection. Cats living in multiple-cat households are at greater risk of the disease. It has been suggested that this disease can move across the placenta from mother to developing kitten; however, the frequency with which this occurs is unknown.

There are 2 forms of this disease: a wet form (effusive) and a dry (noneffusive) form. In the wet form, fluids build up in the abdomen and may restrict the lungs to the point that breathing is difficult. In the dry form, organs such as the liver and kidneys may be involved. The dry form may also involve the eyes, the brain, or both. The disease may start as the wet form and develop gradually into the dry form. If the eyes or the brain are involved, mortality, even with treatment, approaches 100%.

Signs and Diagnosis

The initial infection is often without signs. In some cases, fever, inflammation of the eyes, respiratory signs, and diarrhea may occur. This stage may last several days or weeks before signs of the wet or dry forms develop. Many cats show signs of both forms of feline infectious peritonitis.

Cats with the wet (effusive) form of the disease usually have noticeable fluid build-up in the abdomen. About one-third of cats with effusive disease have lung involvement and difficulty breathing. These signs are often accompanied by fever, poor appetite, weight loss, and depression.

Cats with the dry (noneffusive) form of the disease may have a history of vague illness. This includes repeated fever, malaise, weight loss, and occasionally organ failure (most often the kidneys or liver). Involvement of the eyes and central nervous system may occur either simultaneously or independently of other signs. When the eyes are affected, there may be bleeding or accumulation of pus in one or both eyes. The dry form of feline infectious peritonitis may also attack the nervous system. The most common neurologic sign is poor coordination of muscles with slight paralysis progressing to generalized failure of muscle coordination. Convulsions, personality changes, and increased sensitivity to touch may also be seen.

Your veterinarian can diagnose feline infectious peritonitis based on the cat’s medical history, signs found during a physical examination, and results of laboratory tests.

Treatment, Prevention, and Control

There is no specific treatment for feline infectious peritonitis. Although recovery from signs has been reported, it is uncommon. Up to 95% of cats with feline infectious peritonitis will die from the disease.

In cats with the wet (effusive) form of the disease, the progress is rapid and death usually comes within 2 months. The dry (noneffusive) form of the disease has a more prolonged course. Many cats live several months to a year. Treatment with drugs that reduce inflammation and suppress immune reactions, along with supportive care, can make the cat more comfortable. In some cats (probably less than 10%), treatment may extend survival time by several months. Treatment offers the most hope for cats that are still in good physical condition, still eating, have not yet developed nervous system problems, and that do not have additional disease (such as feline leukemia virus infection).

A vaccine is available to help prevent feline infectious peritonitis. However, many adult cats will have been previously exposed to the virus, so vaccination will not prevent their infection. The vaccine is labeled for use beginning at 16 weeks of age, which may be too late to protect kittens in households where the virus is present. The American Association of Feline Practitioners lists the FIP vaccine as “not recommended.”

Vaccination alone cannot be relied on to control the disease within a cat facility. Other measures to reduce exposure include frequent removal of feces (the primary source of coronavirus), early weaning, and isolation of cats that test positive for coronavirus antibodies. Additionally, isolation and testing of cats after shows, proper sanitation and cleaning using viral disinfectants, and vaccination against other feline viruses can reduce exposure. These control measures should be combined with an overall preventive health program.

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