A 10-month-old, male neutered domestic shorthair presented for not eating or drinking as well as no longer playing with his sibling. On exam, he was quiet, alert and responsive. His eyes and ears were clear and his chest sounded normal. His abdomen was soft and not painful. His bladder was small in size. He had a fever of 104.6 F. It was elected at this time to perform in-house blood work. His blood work revealed borderline elevated globulins. Elevated globulins most likely occur due to systemic inflammation. He was treated for fever of unknown origin including an antibiotic injection, subcutaneous fluids and a highly palatable diet. A recheck was scheduled for three days.
Unfortunately, he represented the next day. He was not improving and had developed cloudiness in his eyes. On exam, both eyes had constricted pupils with white opacities within the anterior chamber. His fever had increased to 105.2 F. It was elected to perform three-view abdominal radiographs. Overall the radiographs were normal. The ocular changes were most consistent with uveitis. Uveitis is inflammation to the inner portion of the eye. With the elevated temperature, borderline high globulins and ocular changes, he was presumptively diagnosed with feline infectious peritonitis (FIP).
FIP is a viral disease of cats caused by a mutation of the feline coronavirus. FIP occurs in one of two forms, a “wet form,” in which fluid accumulates in body cavities like the abdomen and/or chest, and a “dry form,” that affects the central nervous system, resulting in neurologic signs. Unfortunately, there is no definitive test to confirm FIP. Due to this, it is usually diagnosed based on clinical signs, fever, and response to treatment. The treatment for FIP is a complete 12-week course of daily oral tablets known as GS-441524. If truly positive for FIP, cats will respond to treatment within 48-72 hours.
During treatment, it is important to monitor full CBC/chemistry every month to assess hematocrit, globulins, and albumin ratio. Happily, the cat in this case is currently 8 weeks into treatment and responding well.