Fecal proteolytic activity in clinically normal cats and in a cat with exocrine pancreatic insufficiency

Fecal proteolytic activity determined in single samples collected on each of 3 consecutive days from each of 20 clinically normal cats ranged from 19 to 363 azocasein units (ACU)/g of feces when determined colorimetrically, using azocasein substrate, and ranged from undetectable (in 1 sample from 1 cat) to 21 mm of gel-clearing when determined using radial enzyme diffusion in agar gels containing a casein substrate. Corresponding mean 3-day values for each cat ranged from 29 to 207 ACU/g and from 5 to 16 mm, respectively. Studies of proteolytic activity remaining after treatment of fecal extracts with a specific trypsin inhibitor indicated that trypsin accounted for 0 to 77% of proteolytic activity. In a cat with exocrine pancreatic insufficiency, fecal proteolytic activity was 0, 0, and 3 ACU/g in a sample of feces collected from each of 3 consecutive days and was undetectable by use of radial enzyme diffusion. Assay of fecal proteolytic activity by use of either azocasein hydrolysis or radial enzyme diffusion allows evaluation of pancreatic function in cats, provided that several samples of feces are tested.