J Am Vet Med Assoc. 1991 Oct 15;199(8):1060-6.

Hepatotoxicity of phenobarbital in dogs: 18 cases (1985-1989).

Journal of the American Veterinary Medical Association

B Dayrell-Hart, S A Steinberg, T J VanWinkle, G C Farnbach

PMID: 1748613

Abstract

The medical records of 18 dogs that had hepatic disease and received phenobarbital as an anticonvulsant for 5 to 82 months were reviewed. Clinical signs included sedation and ataxia in all dogs, 5 dogs were also anorectic, 2 had coagulopathy, 3 were icteric, and 5 had ascites. Serum biochemical analysis revealed serum albumin concentration less than or equal to 2.2. g/dl in 12 dogs, serum alkaline phosphatase activity greater than or equal to 169 U/L in 18 dogs, serum alanine transaminase activity greater than or equal to 57 U/L in 15 dogs, and total bilirubin concentration greater than or equal to 1 mg/dl (in the absence of lipemia) in 7 dogs. Serum phenobarbital concentration was greater than or equal to 40 micrograms/ml in 12 of 17 dogs. Sulfobromophthalein excretion was prolonged in 8 of 10 dogs. Preprandial serum bile acid concentrations were high in 8 of 10 dogs, and 2-hour postprandial serum bile acid concentrations were high in 9 of 10 dogs. Two of 4 dogs tested had resting plasma ammonia concentrations greater than 200 mg/dl. An ammonia tolerance test was performed on 2 other dogs; both had ammonia concentration greater than or equal to 200 mg/dl in the plasma 30 minutes after receiving 100 mg of ammonium chloride/kg of body weight, PO. Nine dogs died, 1 was euthanatized, and necropsies were performed on these 10 dogs. Biopsies and necropsies of 6 dogs revealed chronic hepatic fibrosis with nodular regeneration (cirrhosis). One dog had hepatocellular carcinoma and mild cirrhosis. In 1 dog, after phenobarbital had been withheld, necropsy revealed complete recovery of the previously observed lesions.

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Substances

• Phenobarbital

MeSH terms

• Animals
• Chemical and Drug Induced Liver Injury
• Dog Diseases / chemically induced
• Dogs
• Female
• Liver / drug effects
• Liver Diseases / veterinary
• Male
• Phenobarbital / adverse effects
• Phenobarbital / therapeutic use
• Retrospective Studies
• Seizures / drug therapy
• Seizures / veterinary

Publication Types

• Journal Article
• Research Support, Non-U.S. Gov't

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