In 2006, a panel of experts assembled by the World Small Animal Veterinary Association (WSAVA) published guidelines for the
standardization of clinical and histologic subtypes of liver disease in small animals.1 These guidelines state that a histologic diagnosis of chronic hepatitis requires the presence of hepatocellular apoptosis
or necrosis, a mononuclear or mixed inflammatory infiltrate, hepatocyte regeneration, and fibrosis. Primary chronic hepatitis
is clinically diagnosed after identification of these characteristic histopathologic findings and exclusion of secondary causes of chronic hepatitis, including associated toxins, infectious agents, and primary metabolic
defects (i.e. copper-associated chronic hepatitis).
Erika Meler, DVM, MS
Although previous studies have examined a variety of clinicopathologic and histopathologic variables in dogs with secondary
chronic hepatitis or chronic hepatitis of all types, no prognostic factor has been identified as of yet in dogs with primary
chronic hepatitis. Because ascites is a well-recognized negative prognostic factor in people with liver disease, the authors'
goal was to compare survival times in dogs with primary chronic hepatitis with or without ascites.
Barrak Pressler, DVM, PhD, DACVIM
In this retrospective study, 34 dogs with clinically and histologically confirmed primary chronic hepatitis were identified
by medical records review, exclusion of dogs with suspected or confirmed secondary causes of liver disease, and review of
original histologic sections of liver by one veterinary pathologist who was blinded to the clinical information. Information
collected for each dog included signalment, date of onset of clinical signs, date of liver biopsy acquisition, the presence
or absence of ascites at the time of biopsy, drugs administered, patient outcome (survival or death or euthanasia from liver-related
or unrelated disease), and date of death.
Free abdominal fluid (ascites) had been noted in 14 of the 34 dogs and was confirmed to be either a pure or modified transudate
in the 11 samples submitted for cytologic examination. Kaplan-Meier survival analysis revealed that the mean survival time
was significantly different between the two groups regardless of the date of onset of liver-related clinical signs or the
date of biopsy. The median survival of patients that died of liver-related causes from the date of biopsy was 24.3 months
for dogs without ascites vs. 0.4 months for dogs with ascites (P < 0.001, meaning that this finding was highly statistically significant). In addition, patients in the nonascitic group were
more likely to have been prescribed a liver-specific diet, whereas patients in the ascitic group were more likely to have
been prescribed spironolactone.