title: Protein-losing enteropathy in dogs is associated with decreased fecal proteolytic activity.
abstract: BACKGROUND
  Measurement of proteolytic activity in feces is a traditional method for the diagnosis of exocrine pancreatic insufficiency (EPI). A drawback of this method is the occurrence of falsely low results that may lead to a false-positive diagnosis of EPI. We hypothesized that intestinal loss of serum proteinase inhibitors in protein-losing enteropathy (PLE) may inhibit fecal proteolytic activity and be a potential source of false low results.
  
  
  OBJECTIVE
  The objective of this study was to determine the effect of PLE on fecal proteolytic activity in dogs.
  
  
  METHODS
  Fecal proteolytic activity was measured using a radial diffusion casein digestion assay in 12 samples from 4 clinically healthy control dogs and 30 samples from 16 dogs with PLE. Gastrointestinal protein loss was assessed using an ELISA to determine fecal canine alpha 1-proteinase inhibitor concentration. The relationship between the concentration of canine alpha 1-proteinase inhibitor in the feces and the diameter cleared in the casein digestion assay was determined. The mean clearing diameter was compared between control dogs and dogs with PLE.
  
  
  RESULTS
  A significant negative correlation was observed between fecal canine alpha1-proteinase inhibitor concentration and casein clearing diameter (P <.001, Pearson r =.6317, r2 =.3999). Mean clearing diameter was significantly lower in dogs with PLE than in control dogs (12.63 vs 16.83 mm, P <.001, two-tailed Student's t-test).
  
  
  CONCLUSIONS
  Increased fecal loss of alpha1-proteinase inhibitor in dogs with PLE is associated with a significant decrease in fecal proteolytic activity and may result in a false positive diagnosis of EPI.
authors.affiliation: Gastrointestinal Laboratory, Department of Small Animal Medicine and Surgery, College of Veterinary Medicine, Texas A&M University, College Station, TX 77843-4474, USA. cruaux@cvm.tamu.edu
authors.forename: Craig G
authors.initials: CG
authors.lastname: Ruaux
authors.forename: Jörg M
authors.initials: JM
authors.lastname: Steiner
authors.forename: David A
authors.initials: DA
authors.lastname: Williams
mesh_terms: D000818:Animals; D002364:Caseins / Q000378:metabolism; D004283:Dog Diseases / Q000175:diagnosis* / Q000201:enzymology; D004285:Dogs; D010188:Exocrine Pancreatic Insufficiency / Q000175:diagnosis / Q000201:enzymology / Q000662:veterinary*; D005189:False Positive Reactions; D005243:Feces / Q000201:enzymology*; D011504:Protein-Losing Enteropathies / Q000150:complications / Q000201:enzymology / Q000662:veterinary*; D000515:alpha 1-Antitrypsin / Q000032:analysis* / Q000378:metabolism
chemical_list: D002364:Caseins; D000515:alpha 1-Antitrypsin