Plasma amino acid profiles of dogs with the hepatocutaneous syndrome and dogs with other chronic liver diseases.

Background: Dogs with hepatocutaneous syndrome (HCS) have marked plasma hypoaminoacidemia, but its occurrence in dogs with chronic liver diseases not associated with HCS (non-HCS CLD) is unknown.

Objectives: To determine if plasma hypoaminoacidemia occurs in dogs with non-HCS CLD, compare plasma amino acid (PAA) profiles between dogs with non-HCS CLD and HCS, and define a sensitive and specific PAA pattern for diagnosing HCS.

Animals: Data were collected from client-owned dogs, a prospective cohort of 32 with CLD and 1 with HCS, and a retrospective cohort of 7 with HCS.

Methods: Prospective study. Dogs with chronic serum liver enzyme increases were recruited after hepatic biopsy. Plasma amino acid profiles were measured using high-performance liquid chromatography. Plasma amino acid concentrations were compared between dogs with non-HCS CLD and HCS. Regression analysis was performed to identify a unique PAA pattern for HCS diagnosis.

Results: Twelve dogs each with vacuolar hepatopathy or chronic hepatitis and 8 dogs with congenital disorders (primary hypoplasia of the portal vein or ductal plate malformations) were enrolled. Compared to non-HCS CLD dogs, HCS dogs had significantly lower plasma concentrations of several amino acids. Regression analysis revealed that glutamine, glycine, citrulline, arginine, and proline concentrations less than 30% of the mean reference value had 100% sensitivity, specificity for diagnosing HCS.

Conclusions and clinical importance: Generalized plasma hypoaminoacidemia does not accompany non-HCS CLD. Concentrations of 5 specific amino acids less than 30% of the mean reference value can serve as a noninvasive biomarker for diagnosing HCS.