DIAGNOSTIC-SIGNIFICANCE OF PLASMA AMMONIA IN DOGS

Plasma ammonia was measured with unitary stabilized reagents (multilay er slides) in 310 dogs of various breeds, ages and sex. Frequent value s do not depend on age (except in newborns in which they are almost tw o times higher) nor on sex or size. They were 43 +/- 6 mu mol/l (m +/- SD). Using 60 mu mol/l as a limit of discrimination, no increase was observed in trauma and in diseases of the eyes, skin, endocrine and se x glands, nervous system, pancreas, urinary tract. In animals having d isease of the liver or of the fiver and other organs, specificity was high : 0.95 and sensitivity was low : 0.25. As a result, negative pred ictive value of this test is low. On the contrary, positive predictive value is higher than 0.50 when pre-test probability is higher than 0. 16. This test is thus useless as a screening test but can be useful fo r the diagnosis of some liver diseases when pre-test probability range s from 0.25 to 0.75.