Pancreatitis, an inflammatory condition of the pancreas, occurs frequently in dogs and cats.^1-3 We do not know the prevalence of pancreatitis in dogs and cats, but recent studies suggest that it is underdiagnosed.^1,2

A recent study of dogs presented for necropsy to the Department of Pathology at the Animal Medical Center in New York, N.Y., showed that 64% of 73 dogs that died or were euthanized for various reasons had evidence of an inflammatory infiltrate of the pancreas.² Although these findings were surprising, this study did not investigate which of these patients had lesions that were clinically significant.²

In a large retrospective study of necropsy findings, 1.5% of 9,342 canine and 1.3% of 6,504 feline pancreata showed important pathologic lesions.¹ Also, according to this study, 59% and 46% of all canine and feline patients with exocrine pancreatic lesions, respectively, had evidence of pancreatitis.¹

Table 1 : Utility of Various Diagnostic Tests for Pancreatitis in Dogs and Cats

CLASSIFICATION

Pancreatitis can be classified based on clinical, etiologic, and histopathologic features.⁴ In the veterinary literature, pancreatitis has been classified based on various parameters, such as histopathologic changes and clinical presentation.^5-8 Unfortunately, a universally accepted multidisciplinary classification has not been proposed or agreed on in veterinary medicine. In contrast, several international multidisciplinary symposia have been held to establish a classification system for pancreatitis in people, and the use of this classification system has been universally agreed on in human pancreatology.⁴ Since this system is based on simple clinical and histopathologic features that are also observed in dogs and cats, I use the human classification system for pancreatitis in dogs and cats.⁴

According to this classification system, pancreatitis can be acute or chronic. Acute pancreatitis is an inflammatory condition of the pancreas that, after removal of the inciting cause, is completely reversible.⁴ In contrast, chronic pancreatitis is characterized by irreversible changes of the exocrine pancreas, such as atrophy or fibrosis.⁴ Both forms of pancreatitis can be mild or severe. Mild forms of pancreatitis are associated with little or no pancreatic necrosis or systemic effects, and affected patients often recover. In contrast, severe forms of pancreatitis are associated with extensive pancreatic necrosis, multiple organ involvement, and often a poor prognosis.

CLINICAL PICTURE

The clinical signs in dogs and cats with pancreatitis depend on the severity of the disease. Mild cases may remain subclinical, while more severe cases may present with a wide variety of clinical signs.

In a recent retrospective study of 70 dogs with fatal pancreatitis, clinical signs reported included anorexia in 91% of the cases, vomiting in 90%, weakness in 79%, abdominal pain in 58%, dehydration in 46%, and diarrhea in 33%.⁷ These findings are somewhat surprising as abdominal pain is the key clinical sign of pancreatitis in people. Thus, the question arises as to whether dogs with pancreatitis have abdominal pain less frequently than people do or, as I think is more likely, whether we fail to correctly identify abdominal pain. Keep in mind that retrospective studies could underestimate the true prevalence of abdominal pain because of lack of reporting, a difference in investigators, or other factors. Classically, diarrhea has not been described as a typical clinical sign of pancreatitis. However, 33% of dogs with fatal pancreatitis in this study had diarrhea, so it seems prudent to evaluate dogs that have diarrhea for pancreatitis.