Page 729 - Clinical Small Animal Internal Medicine

64 Canine Inflammatory Liver Disease 697

including the progressive accumulation of copper in Table 64.1 Age and gender data for breeds with an increased risk
VetBooks.ir hepatocytes starting in zone 3 and leading to the devel- Breed Median age at diagnosis (range) Gender
for developing canine chronic hepatitis
opment of CH. Copper‐associated hepatopathies have
been reported in several breeds of dog including the
Dalmatian, Labrador retriever, Skye terrier, West
Highland white terrier, and Doberman pinscher. These American 5 years 6 months (2 years to 1F, 5M
may not be true copper storage diseases as copper does cocker spaniel 11 years 3 months)
not build up throughout life, and the amount of copper Cairn terrier 10 years 2 months (7 years to 4F, 5M
stored is often not correlated with the severity of the 13 years 5 months)
underlying disease. Although uncommon in the United Dalmatian 4 years 7 months (3 years to 9F, 1M
Kingdom, copper‐associated hepatopathy is increasingly 12 years)
seen in other countries, especially The Netherlands. Doberman 5 years 4 months (2 years 16F, 8M
Disorders associated with excess copper accumulation pinscher 6 months to 10 years)
are covered in more detail in Chapter 62. English cocker 8 years 9 months (1 year 34F, 19M
spaniel 3 months to 14 years)
English springer 5 years (1 year 2 months to 60F, 20M
Epidemiology spaniel 11 years)
Historically, the term canine CH was poorly defined Great Dane 6 years 2 months (1 year 3F, 3M
and used to describe a variety of inflammatory liver dis- 2 months to 7 years 11 months)
eases. The terms chronic active hepatitis and chronic Labrador 8 years 3 months (2 year 63F, 32M
lobar hepatitis were used early in the description of the retriever 8 month to 13 years)
disease, although these names have now largely been Samoyed 10 years (3 years 1 month to 2F, 3M
abandoned in favor of CH. Improvements in the classi- 11 years)
fication of canine CH were brought about by the F, female; M, male.
WSAVA Liver Standardization Group which estab-
lished standardized histologic criteria for diagnosis.
Since the publication of these criteria, one study has cairn terrier, Dalmatian, Doberman pinscher, English
demonstrated a postmortem prevalence of 12% in a cocker spaniel, English springer spaniel, Great Dane,
first opinion practice setting in the UK. Data to assess Labrador retriever, and Samoyed were found to be at
the prevalence of the disease in other countries are not increased risk for developing CH (Table 64.1).
available, although anecdotally CH appears to be the
most frequently identified inflammatory liver disease in History and Clinical Signs
dogs worldwide.
Clinical signs in dogs with CH vary, and are usually
nonspecific and insidious in onset. Sometimes another
Signalment
disease, stress or therapy causes sudden decompensa-
Chronic hepatitis typically affects middle‐aged to tion. The liver has tremendous functional and struc-
older dogs, with the median age for all breeds in a recent tural reserve, and a significant loss of normal hepatic
study being 8 years (range, 7 months to 16 years). Females tissue can occur with minimal or no change in clinical
appear to be predisposed, with a female to male ratio of signs. In addition, the liver has a remarkable capacity to
1.5:1.0 in one study. Several reports detail breed predis- regenerate following hepatic injury, providing the dam-
positions to CH. The first of these was performed on a age is not too severe or ongoing. Overt liver failure does
Swedish population of dogs, and demonstrated that the not develop until at least 70–80% of functional capacity
American and English cocker spaniel, West Highland is lost, so the development of clinical signs implies
white terrier, Labrador retriever, Doberman pinscher, marked impairment of liver function. In addition, some
and Scottish terrier had an increased risk for CH. In this dogs with advanced CH or cirrhosis can be asympto-
study, the disease was reported to occur more commonly matic, or alternatively may present with signs of “acute”
in middle‐aged to older animals and there was a gender liver disease.
predisposition in male English and American cocker The clinician should pay particular attention to subtle
spaniels and female Labrador retrievers. A recent study waxing and waning GI signs, depression, lethargy, ano-
performed in the UK assessed the breed distribution by rexia, weight loss, and polyuria and polydipsia. Additional
comparing the signalment of 551 cases with a histologic signs that may be more suggestive of CH, although still
diagnosis of CH to that of a large control population. not specific, include jaundice, ascites, coagulopathy, and
From a total of 61 breeds, the American cocker spaniel, neurologic signs caused by hepatic encephalopathy.