Feline Infectious Peritonitis
Diksha Kandpal MVSc Scholar College of Veterinary and Animal Sciences Govind Ballabh Pant University of Agriculture and Technology, Pantnagar Diksha.kandpal@gmail.com
Abstract
Feline infectious peritonitis (FIP) is an immune-mediated viral disease of felids caused by Feline coronavirus (FeCV) belonging to coronaviridae family. Feline corona virus is classified into 2 serotypes, Type I FeCV and Type II FeCV. Three different infectious forms has been identified 1) an effusive/ wet form 2) a noneffusive/ dry form and 3) a mixed form. In wet form fluid accumulation is usually observed in either abdominal cavity or thoracic cavity or in both. In the dry form, granuloma formations are observed in various organs. FIP diagnosis is quiet challenging. As in cats noninvasive techniques of confirmatory diagnosis is not available. Immunofluorescence of macrophaegs or immunohistochemistry is considered specific for FIP diagnosis. For prevention of the disease various monovalent and polyvalent vaccines are available. The fatality of the virus in cats is of concern and proper vaccination schedule should be maintained for reduction of the disease occurrences.
Introduction
Feline infectious peritonitis (FIP) is an immune-mediated viral disease of felids caused by Feline coronavirus (FeCV) belonging to coronaviridae family. Feline infectious peritonitis infects young felids of 6-8 weeks of age. The virus is generally transmitted from queens to kitten through oro-fecal route of transmission or in contact with the infected cats. Upon transmission virus causes macrophage and intestinal cells invasion, destroys the intestinal epithelium and villi and causes diarrhea. Virions are found in the cecum, colon, intestinal lymph nodes, spleen, and liver after distribution by macrophages in the whole body, including the CNS. Certain cats remain infected for months without showing clinical sign and act as a source of infection. Three different infectious form of the disease has been identified 1) an effusive/ exudative/ wet form characterized by a fibrinous peritonitis, pleuritis, and pericarditis with effusion in the abdomen, thorax, and pericardium; 2) a noneffusive/ nonexudative/ granulomatous/ parenchymatous/ dry form characterized by granulomatous changes in different organs that includes ocular and nervous system; and 3) a mixed form. Based upon characterization of in-vitro growth ability, and antigenic and structural characteristics Feline corona virus is classified into 2 serotypes, Type I FeCV is strictly feline type and is most prevalent one, whereas Type II FeCV is a combination between FeCV and canine coronavirus and is commonly used in studies and laboratory work.
Factors responsible for infection:
Cats of young age, certain breeds such as Abyssinian, Bengal, Persian, Birman, Himalayan, Ragdoll, and Rex are most susceptible, sexually intact cats, and purebred cats have a higher incidence, Immune status, Stress due to other disease, Corticosteroid treatment, Virulence of coronavirus, Re-infection rate and crowded environments in catteries/ shelters are some of the common predisposing factors.
Signs and symptoms:
Infectious signs include fever with no effective response to antibiotics, reduce apetite, weight loss. In wet form fluid accumulation is usually observed in either abdominal or thoracic cavity or in both. Cats with fluid exhibit labored breathing, muffled heart sound. Cats with fluid in the abdomen show progressive, non-painful abdominal distension. In dry form, granuloma formation is observed in various organs. Depending on the organs involved the signs and symptom varies. In case of liver damage jaundice is observed, in case of kidney involvement increased thirst, urination and vomiting is exhibited. Cats with FIP frequently show ocular and neurologic signs such as ataxia, nystagmus, seizures, incoordination, hyperesthesia, behavioral changes and hydrocephalus upon CT scan. It also damages cranial and peripheral nerves. In case of cranial nerves visual deficits and menace reflex are present and in case of peripheral nerves lameness, progressive ataxia, or paresis may be seen. Histological diagnosis of the feline infectious peritonitis involves intestinal lesions. Kittens infected with virus shows stunted growth, upper respiratory tract symptoms and are generally unresponsive to treatment.
Diagnosis
FIP diagnosis is quiet challenging as it is difficult to differentiate harmless intestinal form from infectious FIP coronavirus infection. Moreover, in case of cats noninvasive techniques of confirmatory diagnosis is not available. Histology of lesions is usually pathognomonic and is considered gold standard for diagnosis of FIP. The diagnostic parameters include:
· Hematology and Serum analysis reveals lymphopenia along with moderate non-regenerative anemia is observed but these are non specific. Increase in total serum protein concentration is observed in cats that can reach upto concentrations of ≥12 g/dL. An increased serum albumin to globulin ratio greater than 0.8g/dL is suggestive of infection of cat with FIP.
· Diagnostic Imaging reveals abdominal lymphadenopathy, peritoneal or retroperitoneal effusion, irregular renal contour, and diffuse changes within the intestines. Effusion Fluid has a much higher diagnostic value than tests performed on blood. Rivalta test is conducted to differentiate between effusions caused by FIP and other diseases.
· Analysis of cerebrospinal fluid reveals increased protein value upto 50–350 mg/dL and pleocytosis (100–10,000 nucleated cells/mL).
· Feline Coronavirus Reverse Transcriptase PCR tests is also seldomly used however, PCR interpretation is not the only criteria that definitively confirm FIP.
· Immunofluorescence of macrophaegs in cytocentrifuged effusions or immunohistochemistry in tissue is considered specific for FIP diagnosis.
Treatment and Prevention:
Treatment in case of FIP is supportive including fluids to correct the fluid electrolyte imbalance. The treatment depends upon the favourable response in earlier days. The prognosis in affected case is very poor however some cats may survive upto months. Cats that do not show improvement within initial 3-4 days of treatment are likely to remain infected with virus and euthanasia should be considered in such cases. Removal of fluid is effective treatment in cats with effusion, further, injection of dexamethasone into the abdominal or thoracic cavity may follow. It is important to advice the owner about the outcome of this fatal disease.
Control and Management:
Feline infectious peritonitis is common problem in catteries, shelters and multi-cat households. Crowded place, sharing of liter boxes are some of the reasons favoring predisposition of cat for disease development. However, proper disinfection of the house or the area where cats are kept proves effective. As the virus may survive on inanimate objects and these acts as source of disease transmission to other cats and therefore, clothes toys, grooming tools of infected cats should be properly disinfected or discarded. Good husbandry practices should be followed. If a cat has died out of FIP, the owner should wait for a minimum of 2 months before obtaining another cat as the virus remain infectious for at least 7 weeks in the environment.
For reducing the occurrence of disease proper vaccination in cats should be followed there are various monovalent (single) or polyvalent (combination) vaccine available for prevention of disease in cats. Vaccine for FIP is administered intranasally and produces local immunity. Felocell FIP (IN) is for intranasal (IN) vaccination of healthy cats of 16 weeks of age or older and helps in preventing infection from feline infectious peritonitis virus (FIPV). However, the use of FIP vaccine is controversial and the American Association of Feline Practitioners lists the FIP vaccine as “not recommended.”
Conclusion:
Coronavirus causes various other diseases including severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS), these diseases have shown zoonotic potential and have shown disease outbreaks in humans. However, the occurrence of feline corona virus causing FIP has not yet been discovered in humans. However, the fatality of the virus in cats is of concern and proper precaution and vaccination schedule should be maintained for reduction of the disease occurences.
References
1. https://www.vet.cornell.edu/departments-centers-and-institutes/cornell-feline-health-center
2. https://pets.webmd.com/cats/cat-fip-feline-infectious-peritonitis
3. Addie, D., Belák, S., Boucraut-Baralon, C., Egberink, H., Frymus, T., Gruffydd-Jones, T., Hartmann, K., Hosie, M.J., Lloret, A., Lutz, H. and Marsilio, F., 2009. Feline infectious peritonitis. ABCD guidelines on prevention and management. Journal of Feline Medicine & Surgery, 11(7), pp.594-604.
4. Felten, S. and Hartmann, K., 2019. Diagnosis of feline infectious peritonitis: a review of the current literature. Viruses, 11(11), p.1068.
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