Validation of the determination of the activity of adenosine deaminase in the body effusions of cats.

In order to identify parameters differentiating exudative from transudative effusions, it was postulated that the activity of adenosine deaminase (AD) (EC 3.5.4.4) might be highly correlated with granulomatous inflammatory processes of the serosa, and the activity of the enzyme in body effusions and serum from cats was examined. The method of Slaats et al (1985) for the determination of the enzyme was evaluated by using an Hitachi 705 autoanalyser, and its activity was measured in body cavity effusions of 174 cats. The activity of AD was high in effusions from cats with infectious serositis and bacterial or feline infectious peritonitis (FIP). In cases of FIP the activity of AD was very significantly different from all other cases of thoracic (P = 0.004) and abdominal (P < 0.0001) effusions. The determination of AD in the serum of cats did not contribute to the aetiological differentiation of hydrops. The increases in the activity of AD appeared to originate from the body effusion, because the ratio of the activity of the enzyme in the effusion to its activity in serum was relatively high in cases of FIP.