Page 436 - Problem-Based Feline Medicine

428 PART 7 SICK CAT WITH SPECIFIC SIGNS

the observation that inflammatory disease of other ali- ● Mild to severe infiltration of portal areas by plasma
mentary organs, such as pancreatitis and inflammatory cells, lymphocytes and neutrophils, without or
bowel disease, are associated with cholangitis. without macrophages is present. Leukocytes are
within walls and/or lumina of bile ducts, and are
A new classification scheme by the World Small
associated with biliary epithelial degeneration or
Animal Veterinary Association Liver Diseases and
necrosis. Lymphoid aggregates may be present in
Pathology Standardisation Research Group recognizes
portal areas. Biliary hyperplasia, periductal fibrosis
three distinct forms of cholangitis in cats.
or bridging portal fibrosis may be present.
In the traditional classification scheme, cholangitis ● It is usually associated with partial or complete bil-
denoted inflammation of the biliary tree and cholangio- iary obstructive lesions resulting in cholestasis.
hepatitis referred to inflammation around bile ducts and ● Signs and liver enzyme elevations tend to be milder
peribiliary hepatocytes. than with the acute neutrophilic phase, and reflect a
smoldering inflammatory hepatic disease. Weight
However, with the new classification scheme, the term
loss is a dominant sign. Signs may wax and wane.
cholangitis is used in preference to cholangiohepatitis,
Jaundice may or may not be present. Ascites is not
because inflammatory disruption of the limiting plate to
a feature of the acute or chronic phase. In general,
involve hepatic parenchyma is not always a feature and,
the chronic phase appears less common than the
when present, is an extension of a primary cholangitis,
acute phase.
and inflammation is centered on intrahepatic bile ducts.
Lymphocytic cholangitis.
Three separate syndromes occur as defined by clini-
● Lymphocytic cholangitis is postulated to be
cal and histologic criteria: neutrophilic cholangitis,
immune-mediated in origin.
lymphocytic cholangitis and chronic cholangitis.
● Histologically there is moderate to marked infiltra-
Cirrhosis may occur as an end-stage of cholangitis but tion of portal areas by small lymphocytes. With
is rare. chronicity, the intensity of portal infiltration tends
● The lymphocytic form is more common than the to abate. Lymphocytic infiltrates may also be pres-
neutrophilic form of cholangitis in the UK and ent that are centered on and infiltrating walls of bile
Australia, but the neutrophilic form appears to be ducts, but this is an inconsistent feature, especially
the most common form in some other locations. in the chronic phase. Inflammation may or may not
extend into the periportal parenchyma. Histologic
Neutrophilic cholangitis.
evidence of intrahepatic cholestasis may be present.
● This is usually referable to ascending bacterial infec-
● It occurs primarily in middle-aged cats with chronic
tion but is also rarely reported in protozoal infec-
(> 3 weeks) signs. Recurrent episodes of clinical
tions. E. coli is sometimes cultured from the bile, and
signs are often interspersed with weeks or months of
occasionally Gram-positive anaerobes are cultured.
normalcy, with a normal or even increased appetite.
● Two phases of neutrophilic cholangitis are recog-
● Cats are often less ill than with the acute neu-
nized; an acute phase and a chronic phase.
trophilic form, and may have ascites.
Neutrophilic cholangitis – Acute phase.
Chronic cholangitis associated with liver fluke infes-
● Neutrophils are within walls and lumina of intra-
tation.
hepatic bile ducts and within portal areas. Bile duct
● Lesions result from infection by liver flukes such as
epithelial degeneration and necrosis is present.
Amphimerus pseudofelineus, (Opisthorchis pseudo-
There is variable extension of inflammation through
felineus), Opisthorchis tenuicollis, Metorchis albidus,
the limiting plate to involve periportal parenchyma.
M. conjunctus (M. complexus), Platynosomum
Bacteria may be visible. There is usually minimal
concinnum (page fastosum).
biliary hyperplasia or periductal fibrosis.
● Generally, there is an acute onset of signs with marked
systemic illness (fever, anorexia, lethargy, vomiting). Clinical signs
Neutrophilic cholangitis – Chronic phase. Often observed in middle-aged cats.