Symptoms of Feline Infectious Peritonitis

1 Feline Infectious Peritonitis

Epidemiology

Cats of any breed and age are susceptible, but those 6 months to 2 years old have the highest infection rate. Infection is mainly via the digestive tract; insects can also transmit it.

Clinical symptoms

(1) Effusive (wet) form

Early signs: temperature 39.7-41.1°C, depression, reduced appetite, weight loss and increased white blood cells. Within 1-6 weeks the abdomen swells (females are often mistaken for pregnant), and up to 1000 mL of fluid can be drained; labored breathing, anemia and exhaustion follow.

(2) Non-effusive (dry) form

No ascites. Eye involvement: corneal edema, precipitates, red aqueous humor, fibrin clots in the anterior chamber, iris ciliary body inflammation, retinal detachment. CNS involvement: movement disorders, ataxia, back hypersensitivity, spasms. Liver damage: enlargement, jaundice; kidney failure and enlargement.

Pathological changes

Abdominal effusion, clear or slightly yellow, sometimes egg-white like, coagulating on contact with air. Peritoneum is cloudy, granular and rough, covered with fibrin; also on liver, spleen and kidney surfaces. Liver surface has 1-3 mm necrotic foci, visible deep into the parenchyma on cut. Non-effusive form: CNS involvement, no ascites, cerebral edema, uneven kidneys, liver necrosis.

Differential diagnosis

(1) FIP vs. feline toxoplasmosis

Both show high temperature (above 40°C), anorexia, anemia, distended abdomen, labored breathing and iris inflammation.

Difference: toxoplasmosis is caused by Toxoplasma. Affected cats are unsteady, trembling, with nasal discharge, cough and sometimes vomiting. Urine bilirubin (++), urobilin (+++), reduced white cells. Necropsy: congestion on hind limbs, abdomen and ears, subcutaneous hemorrhage, pulmonary edema with scattered nodules; impression smears Wright’s-stained show Toxoplasma.

(2) FIP vs. feline leukemia

Both show high temperature, depression, poor appetite and anemia.

Difference: leukemia shows generalized lymph node, liver and spleen enlargement, petechiae on mucosa and skin, much pleural effusion. Smears show many immature lymphocytes.

(3) Effusive FIP vs. feline liver fluke infection

Both show reduced appetite, anemia, abdominal distension and ascites.

Difference: liver fluke cases have normal temperature and diarrhea. Fecal exam shows eggs; palpation reveals enlarged liver, necropsy shows surface nodules.

Notes

A preliminary diagnosis is based on epidemiology, clinical signs and pathological changes; confirmation requires laboratory testing.

Prevention and treatment

(1) Prevention

There is no effective vaccine yet; only better management, disinfection and infection control.

(2) Treatment

Treatment aims to boost resistance and provide symptomatic care.

1. Interferon: 20,000 IU/kg, oral or subcutaneous, once daily.

2. Prednisone: 2-4 mg/kg orally 1-2 times daily, combined with cyclophosphamide.

3. Cyclophosphamide: 2 mg/kg orally once daily, 4 days/week, combined with prednisone.

4. Chlorambucil: 0.5 mg/kg orally 2-3 times weekly.

5. Ampicillin: 20-30 mg/kg orally 2-3 times daily; or 10-20 mg/kg subcutaneous, intramuscular or IV 2-3 times daily.

6. Clavamox (amoxicillin-clavulanate suspension): 0.1 mL/kg subcutaneous or intramuscular, once daily.