Feline Infectious Peritonitis

Overview

FIP is a generalised, viral disease characterised by subtle onset of signs, persistent fever that does not respond to treatment, inflammatory nodular tissue reaction with the presence of pus, accumulation of inflammatory fluids in body cavities, and high mortality.  FIP is caused by a mutation of the endemic feline enteric coronavirus strain.  Occurs mostly in catteries. Effusion tends to form in cats with poor cell-mediated immune response.

Species and Breed Predisposition

• Both domestic and exotic cats.

• British-shorthair tends to be over-diagnosed, more so than other breeds. 

Mean age and Range

• Highest incidence of disease occurs in kittens 3 months to 3 years of age.

• Incidence of disease decreases sharply after cats reach 3 years of age.

Pathophysiology

• Transmission of coronavirus is both oral and respiratory. Therefore it is important to wash hands after handling, and not to handle kittens. 

• There are two forms of FIP - immune complex mediated vasculitis (effusion - wet) and necrosis/pyogranulomatous inflammation (dry).

Clinical Signs

• Fever - unresponsive to antibiotics.

• Anorexia, weight loss, lethargy, vomiting, diarrhoea, dehydration and anaemia.

• Wet form:

- Acute - peritonitis/abdominal effusion (85%).

- Progressive non-painful distension of abdomen.

- Jaundice - without hepatomegaly when under two years of age.

- Vomiting.

- Adhesions: large mass of guts.

• Dry form:

- Non-effusive.

- Pyogranulomatous lesions - organ specific. 

- Kidney - PU/PD.

- Icterus, hepatomegaly.

- CNS.

- Anterior uveitis.

Diagnosis

• Base on - history, clinical signs, physical exams, cytology, radiographs, ultrasound, fluid analysis and biopsy.

• Physical exam - auscultation muffled heart sounds, fluid wave, palpation of lymphatic, hepatomegaly, enlarged firm kidneys, and pyogranulomatous.

• Lab - CBC anaemia, leukocytosis, lymphopenia (PCV) - Biochemistry azotemia, liver enzymes and bile acids.

• Rads and US - confirm body cavity effusion.

• Fluid analysis - pale yellow, transudate:

- Protein concentration ranges from 3.5g/dl to 12 g/dl.

- Inflammatory cells.

- Albumin to globulin ratio is less than 0.81 or albumin is less than 48% of the total protein.

- Total protein concentration is greater than 3.5 g/dl and globulin component is greater than 50% of the total protein concentration.

• Corona virus serology - can’t differentiate between corona and FIP corona.

Treatment

• No treatment

• Supportive treatment but short survival time:

- Intermittent body cavity drain.

- Fluid therapy.

- Nutritional support.

- Blood transfusion.

• Antibiotics - treat secondary infection.

Prognosis

• Grave.

• Wet form: survival from days to up to two months.

• Dry form: survival up to one year.

Prevention

• Coronavirus can survive in dried secretion for up to 7 weeks - routine disinfection.

• Healthy coronavirus-seropositive cats shed virus.

• Seronegative cats do not shed virus.

• Kittens not infected by transplacental.

• Maternal derived coronavirus antibodies wane by 4 to 6 weeks of age.

• Kittens are most like to become infected by contact with cats when antibodies wane.

• Coronavirus antibodies due to natural infection develop by 8-14 weeks of age.