Pancreatitis is being diagnosed more and more frequently in cats. Cats typically have chronic pancreatitis whereas dogs usually
suffer acute disease. The difference in presentation between the species as well as a lack of appropriate diagnostic tools
led to pancreatitis in cats being widely underdiagnosed. As we have learned to recognize the more subtle presentation in
cats as well as having developed better tests, veterinarians have come to realize that pancreatitis is not uncommon in cats.
Pancreatitis is the end-result of autodigestion of the pancreas by the activation of digestive enzymes within the pancreas.
A variety of different mechanisms can start this process which then results in pancreatic autodigestion. Following an insult,
there is initially a decrease in the secretion of pancreatic enzymes. This results in the formation of abnormal cytoplasmic vacuoles. Inside these vacuoles,
the contents of the lysozomes and zymogen granules colocalize, leading to intracellular activation of trypsin. The activation
of trypsin leads to activation of other zymogens, including proteases and phospholipases. The activated digestive enzymes
can cause both local and systemic effects. Local effects include pancreatic inflammation, hemorrhage, cellular necrosis,
and peripancreatic fat necrosis. Systemic effects may arise from release of the activated digestive enzymes into the bloodstream.
Potential systemic effects may include hypotension from vasodilation, pulmonary edema, pleural effusion, disseminated intravascular
coagulation, renal failure, and multi-organ failure.
In most cases of feline pancreatitis, the underlying cause is unknown. There are a few infectious agents that have been associated
with pancreatitis in cats. Toxoplasma gondii infection has been shown to cause pancreatitis as has the hepatic fluke Amphimerus pseudofelineus. Close to 1/5 of cats with pancreatitis have antibodies against Bartonella sp. Some viral agents such as panleukopenia and feline infectious peritonitis have also been implicated. Blunt abdominal
trauma can lead to pancreatitis, most likely secondary to ischemia. Unlike the situation in humans where drugs are commonly
implicated as the cause of pancreatitis, drugs have very rarely been shown to have a cause-and-effect relationship with feline
pancreatitis. Organophosphate intoxication has been documented to cause pancreatitis in cats. While still not fully understood,
there is a suspected relationship between pancreatitis in cats and inflammation in neighbouring organs including the liver
and/or gastrointestinal tract. Whether "triaditis" (concurrent pancreatitis, hepatitis, and inflammatory bowel disease) is
a true clinical entity is hotly debated; however, definite associations between pancreatitis and inflammatory bowel disease
are frequently seen. Pancreatitis is also seen in conjunction with hepatic disease.
The history and presenting complaints for cats with pancreatitis varies tremendously. Examination of the literature does
not suggest any strong age, breed or sex predilection. While pancreatitis has been diagnosed in cats as young as five weeks
of age, there is some suggestion that pancreatitis is more likely to be seen in middle-aged and older cats. Cats typically
present with chronic pancreatitis. Studies of pancreatitis in cats suggest that a more chronic form is seen in 65-89% of
all cases of pancreatitis. The clinical signs most often reported are very non-specific and include lethargy, anorexia and
weight loss. Less commonly seen are the "classic" signs of pancreatitis such as vomiting and abdominal pain. A small percentage
of cats will present as the typical acute pancreatitic with a very brief history of extreme lethargy and vomiting. Perhaps
the most classic aspect of pancreatitis in cats is in illustrating the fact that cats aren't small dogs!
Physical examination findings in cats with pancreatitis are non-specific as well. Dehydration and depression are frequently
seen. Mucous membranes may be pale or icteric. Abdominal pain or palpable abdominal masses are infrequently noted. Changes
in respiration including tachypnea and dyspnea have been reported.