Determination of plasma alpha-amylase in the dog: a test of the specificity of new methods.

Commercially available chromogenic substrates for the assay of alpha-amylase were tested for specificity in dog plasma. Blocked alpha-4-nitrophenylmaltoheptaoside and non-blocked beta-4-nitrophenylmaltoheptaoside showed no interference with glucoamylase and were suitable for the measurement of alpha-amylase in dog plasma. In contrast, an alpha-4-nitrophenylmaltoheptaoside showed interference, and was therefore an inappropriate substrate. Reference values with the blocked substrate in a group of 82 non-selected 3 month- to 10 year-old male and female dogs were 355 +/- 131 U/l (mean +/- standard deviation) at 30 degrees C.