Dr Caitlin Canning (BVSc) Internal Medicine Intern

FIP originates from an in vivo mutation of Feline enteric coronavirus resulting in change of tropism from intestinal epithelial cells to macrophages. Individual immune response and viral load contribute to pathogenesis, resulting in vasculitis and effusion (wet form) with formation of perivascular pyogranulmatous lesions (dry form). Prevalence up to 5% in multi cat households/cattery situations, more likely to be young purebred cats <2 years of age.

Affected cats often present after a recent stressful event (neutering, adoption) with weight loss/failure to thrive, pyrexia and effusion. Characteristic findings on blood work include elevated globulins (A:G <0.8), hyperbilirubinaemia, lymphopaenia and mild anaemia.

Definitive diagnosis requires consistent histopathological changes in tissue with positive immunohistochemistry for coronavirus. Effusion can strongly support a diagnosis and immunofluorescence staining of effusion and FNA’s of granulomas show promise in expediting a diagnosis by less invasive means. All tests should be used together to increase index of suspicion and confidence in the diagnosis.

Traditionally considered a terminal diagnosis with life expectancy as little as 8 days post diagnosis (possibly skewed by veterinarian recommendations to euthanase), recently new antiviral treatments have shown potential.

  • Researchers at University of Sydney are currently investigating the use of Mefloquine (an antimalarial used in cases of Chloroquine resistance), supported by a grant from the Winn Feline foundation. There are no study trials available currently.
  • GC376 a protease inhibitor is being developed for use in cats and has shown great success but is still 10+ years away from commercial access.
  • GS441524 a nucleoside analogue is currently being developed for use as a human pharmaceutical in treating viral diseases such as COVID19 (as prodrug Remdesivir).
  • There is a large black market particularly for GS and owners in China, America and Australia are importing it for use in their cats with promising results in many cases. Treatment is loosely based off study trials conducted at UC Davis led by Dr. Niels Pedersen, these studies are available open access online.