Page 281 - Problem-Based Feline Medicine

16 – THE CAT WITH ACUTE DEPRESSION, ANOREXIA OR DEHYDRATION 273

The pathogenesis of acute pancreatitis is believed to be
Pathogenesis
similar to that in other species:
Pancreatitis is typically classified based on post- ● Premature zymogen activation occurs within the
mortem pancreatic histopathology. Classification pancreas leading to local inflammation, circulating
schemes vary in different reports, but in general the pancreatic enzymes, and systemic inflammatory
degree of fibrosis and mononuclear cell infiltration cor- response syndrome (SIRS). Potential sequelae
relates with chronicity. include hypotension, disseminated intravascular
● Acute pancreatitis is characterized by variable coagulation (DIC), pulmonary edema, pleural effu-
neutrophil infiltration, edema, hemorrhage, acinar sion, pulmonary thromboembolism, encephalopathy,
necrosis and peripancreatic fat necrosis, inflamma- systemic lipodystrophy, acute renal failure and multi-
tion (steatitis) and saponification. In one series of organ failure.
40 cats, acute pancreatitis was categorized as necro- ● Neither bacterial infection of the inflamed pancreas
tizing pancreatitis (some with fibrosis) and suppu- nor bacteremia appears to be common in naturally
rative pancreatitis. occurring pancreatitis.
● Both acute and chronic pancreatitis can be severe
and no clinical, laboratory or diagnostic imaging Clinical signs
finding reliably distinguishes the two.
Cat may be of any age, with no sex or breed predilec-
Pancreatitis may occur with or without concurrent
tion, except perhaps for Siamese cats.
disorders. In the absence of a concurrent condition,
a specific cause is usually not identified. Duration of clinical signs prior to presentation varies
● Identified causes of acute pancreatitis include pan- from several days to more than 3 weeks. Both acute
creatic neoplasia, hypothermia, virulent systemic and chronic pancreatitis may present with acute signs,
feline calicivirus strains, ascending bacterial but cats presenting with a longer clinical history are
infection, toxoplasmosis, abdominal trauma and more likely to have pancreatic fibrosis.
organophosphate intoxication. Ingestion of a high-
Clinical findings are often more subtle than expected
fat meal is not a cause, unlike in dogs. Pancreatic
for the degree of pancreatic injury. This may explain in
flukes (Eurytrema procynonis) and liver flukes
part the delay in presentation to a veterinarian.
(Amphimerus pseudofelineus) have been associ-
ated with chronic, but not acute, pancreatitis. The Depression and/or anorexia are the most common
cat has been used extensively as an experimental historical signs and may be the only signs present. The
model of acute pancreatitis, but the methods of most common physical abnormalities are dehydra-
inducing pancreatic inflammation have little rele- tion and hypothermia (68% in one study). Fever is
vance to the etiology of naturally occurring disease. uncommon.
● Associated disorders include hepatic lipidosis,
Other inconsistent signs include weight loss, vomit-
cholangiohepatitis, inflammatory bowel disease,
ing, diarrhea, cranial abdominal pain, cranial abdomi-
diabetes mellitus, diabetic ketoacidosis and acute
nal mass, abdominal distention due to ascites, dyspnea,
renal failure. Cause and effect between these condi-
ataxia and disorientation and shock. Polydipsia may be
tions and pancreatitis is not known, but the disor-
present, but is usually due to concurrent diabetes melli-
ders are probably related. Other concurrent
tus. Systemic lypodystrophy is a rare complication of
disorders include chronic renal diseases and neo-
acute pancreatitis, characterized by subcutaneous nod-
plasia, which may be related to age rather than pan-
ules that may ulcerate.
creatitis. If a concurrent disorder is not identified,
pancreatitis is more likely to be acute based on
histopathology. Diagnosis
● Obesity is not an independent risk factor, but is a
Because clinical and laboratory findings are non-spe-
risk factor for conditions associated with pancreati-
cific, diagnosis requires a high index of suspicion.
tis, such as hepatic lipidosis and diabetes mellitus.
Cats with pancreatitis may be thin, but it is not clear Pancreatitis should be considered in any cat with
if this is a risk factor or consequence of anorexia. unexplained acute depression. Acute pancreatitis