Within the veterinary hospital there are a number of tests which can rule out a diagnosis of effusive FIP within minutes:
Measure the total protein in the effusion: if it is less than 35 g/L, FIP is extremely unlikely.
Measure the albumin to globulin ratio in the effusion: if it is over 0.8, FIP is ruled out; if it is less than 0.4, FIP is a possible—but not certain—diagnosis.
Examine the cells in the effusion: if they are predominantly lymphocytes (a type of white blood cell), then FIP is excluded as a diagnosis.
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