Page 754 - Clinical Small Animal Internal Medicine

722 Section 7 Diseases of the Liver, Gallbladder, and Bile Ducts

strong association of IBD with primary sclerosing chol­
VetBooks.ir angitis in humans. Although such a strong association is
not reported in dogs, inflammation around the duodenal
papilla can alter bile flow and may encourage bacterial
colonization of the biliary tract. Likewise, intestinal
motility disorders or small intestinal bacterial over­
growth may augment infection risk by increasing
numbers of potentially pathogenic bacteria that may
ascend the biliary tract.
Biliary flukes are not prevalent in Europe, but are more
commonly found in the southern USA, South America,
and Asia. Infection requires ingestion of a secondary
intermediate host such as a frog or lizard.

Signalment

Particular species and breed associations are found for
certain biliary disorders. Neoplasia occurs more com­
monly in middle‐aged to older cats and dogs, but benign
and cystic disorders may be acquired even in individuals
less than 2 years of age. Biliary flukes are reported in cats
but are far less common in dogs. Mucocele formation is
more common in Shetland sheepdogs, border terriers,
miniature schnauzers and cocker spaniels and become
increasingly common in dogs beyond middle age.
Figure 67.1 A distended gallbladder removed from a dog with a Mutation of a phosphatidylcholine translocator (ABCB4)
mucocele. has been identified in affected Shetland sheepdogs.
Choleliths are more commonly found in miniature
Primary biliary neoplasia ranges from benign chole­ schnauzers and miniature poodles, particularly in older
dochal cysts and biliary cystadenoma to biliary carci­ females.
noma, which may originate in the intrahepatic or Pancreatic neoplasia does not have a strong breed pre­
extrahepatic biliary system. Biliary neoplasia occurs more disposition, but pancreatitis is more commonly associ­
commonly in cats. The gallbladder is susceptible to infarc­ ated with cocker spaniels and miniature schnauzers. Of
tion if the cystic artery – the sole arterial blood supply to note is the often marked inflammatory swelling of the
the organ – is compromised by trauma or thrombosis. pancreas in cocker spaniels with pancreatitis, which may
Bacterial cholangitis may occur due to ascending bac­ be erroneously described as a pancreatic tumor based on
terial infection from the gastrointestinal tract, hematog­ diagnostic imaging findings. Those breeds with predis­
enous spread or colonization by the aforementioned positions towards endocrine disease (e.g., hypothyroid­
transitory bacteria. ism, hyperadrenocorticism) may be more commonly
affected by bile stasis, cholangitis, and biliary mucocele.

Epidemiology
History and Clinical Signs
Arguably, the most common disorders predisposing to
biliary tract disease are endocrine diseases such as Nonobstructive biliary tract disease may be insidious in
hyperadrenocorticism, diabetes mellitus, and hypothy­ onset, with vague clinical signs such as lethargy, pyrexia,
roidism. Of these, hyperadrenocorticism increases risk anorexia, and vomiting. Pyrexia is more likely to be pre­
of gallbladder mucocele by up to 29 times; the associa­ sent with florid inflammation, bile peritonitis or bacterial
tion with hypothyroidism and diabetes mellitus is less biliary infection but can also be seen with cholelithiasis,
concrete. presumably due to secondary bacterial infection. Clinical
Inflammatory bowel disease (IBD) is a common co‐ signs may be mild and therefore present for weeks or
morbidity with cats with cholangitis, just as there is a months before veterinary attention is sought.