Darcy H. Shaw

Liver Histopathology and Liver and Serum Alanine Aminotransferase and Alkaline Phosphatase Activities in Epileptic Dogs Receiving Phenobarbital

Phenobarbital (PB) therapy is frequently associated with elevated serum alanine aminotransferase (ALT) and alkaline phosphatase (AP) activities in dogs without clinical signs of liver disease. The goal of this study was to determine if increased serum ALT and AP activities in clinically healthy PB-treated epileptic dogs are due to hepatic enzyme induction or to subclinical liver injury. Liver biopsies were obtained from 12 PB-treated dogs without clinical signs of liver disease but with elevated serum ALT and/or AP activities or both. Liver biopsies were obtained from eight healthy control dogs not receiving PB. Biopsies were evaluated histopathologically (all dogs) and liver homogenates were assayed for ALT (all dogs) and AP (six treated dogs, all controls) activities. As a positive control, liver cytochrome P4502B, an enzyme known to be induced by PB, was measured by benzyloxyresorufin-O-dealkylase activity and immunoblotting (five treated dogs, all controls). Serum AP isoenzyme analyses were performed. Results showed that ALT and AP activities in liver homogenates were not increased in treated dogs compared with controls, whereas the positive control for induction, CYP2B, was dramatically increased in treated dogs. Histopathological examination of liver biopsies revealed more severe and frequent abnormalities in treated dogs compared to controls, but similar types of abnormalities were found in both groups. Serum AP isoenzyme analyses in treated dogs demonstrated increased corticosteroid-induced and liver isoenzyme activities compared to controls. Results do not support induction of ALT or AP in the liver as the cause of elevated serum activities of these enzymes due to PB.

Association between excess body weight and urine protein concentration in healthy dogs

BACKGROUND Markedly overweight people can develop progressive proteinuria and kidney failure secondary to obesity-related glomerulopathy (ORG). Glomerular lesions in dogs with experimentally induced obesity are similar to those in people with ORG. OBJECTIVES The aim of this study was to evaluate if urine protein and albumin excretion is greater in overweight and obese dogs than in dogs of ideal body condition. METHODS Client-owned dogs were screened for underlying health conditions. These dogs were assigned a body condition score (BCS) using a 9-point scoring system. Dogs with a BCS of ≥ 6 were classified as being overweight/obese, and dogs with a BCS of 4 or 5 were classified as being of ideal body weight. The urine protein:creatinine ratio (UPC) and urine albumin:creatinine ratio (UAC) were then determined, and compared between 20 overweight/obese dogs and 22 ideal body weight control dogs. RESULTS Median UPC (0.04 [range, 0.01-0.14; interquartile range, 0.07]) and UAC (0.41 [0-10.39; 3.21]) of overweight/obese dogs were not significantly different from median UPC (0.04 [0.01-0.32; 0.07]) and UAC (0.18 [0-7.04; 1.75]) in ideal body weight dogs. CONCLUSIONS Clinicopathologic abnormalities consistent with ORG were absent from overweight/obese dogs in this study.