Page 637 - Clinical Small Animal Internal Medicine

56 Pancreatitis in the Cat 605

difficulty of assessing these tests comes from the obser­ low diagnostic yield is a contraindication for its use in
VetBooks.ir vation that we do not truly know the prevalence of pan­ most cases.
The increasing availability of high‐resolution abdomi­
creatic disease in the feline population. While at least
one study suggests that pancreatic pathology is quite
common in the feline population (approximately 60% of nal ultrasonography in companion animal practice has
dramatically improved the use of diagnostic imaging to
cases necropsied, where the patient was not suspected to characterize pancreatic disease in the cat. Observation
have pancreatic disease), one caveat about this study is of pancreatic enlargement, hyperechoic mesentery and
that these were still, largely speaking, unwell cats that abdominal fat, altered parenchymal echogenicity (most
were necropsied. If the true prevalence of pancreatic dis­ commonly hypoechogenicity or a mixed pattern),
ease in the feline population is as high as 60%, then an abdominal effusions, pancreatic cysts or pseudocysts,
unexpected finding of a high Spec‐fPL concentration or corrugation of the duodenum, and dilation of the pan­
DGGR‐lipase activity on sentinel chemistry panels may creatic duct are all considered consistent with pancreati­
be a true indication of pancreatic disease. While the pan­ tis in cats with consistent clinical signs. These findings
creatic disease present may not be an important clinical are specific indicators of the presence of pancreatic
finding, this does not mean that this is an incorrect diag- pathology, but their sensitivity for accurate diagnosis in
nostic finding. This is particularly true when the clinical cats with histologically confirmed pancreatitis is quite
chemistry panel is being run on an apparently healthy variable, with reported sensitivities ranging from ~11%
patient as part of a health monitoring or wellness to 80%. Sensitivity of abdominal ultrasound for the
program. detection of feline pancreatic disease is highly dependent
An additional important factor in the interpretation of on operator skill and equipment resolution. Given the
these tests is the very variable, and often subtle, clinical variable and often low sensitivity of abdominal ultra­
signs and histories of this disease, as previously dis­ sound examination in the diagnosis of pancreatitis in
cussed. When clinical chemistry panels and Spec‐fPL cats, this modality cannot be reliably used as a “rule‐out”
tests are being run as part of a broad‐ranging assessment test for this disease. However, significant additional
in a cat that is known to be unwell, but with no clear ini­ information useful for management of these cases is
tial indication of why, abnormalities in these tests are a often obtained, particularly when screening for co‐
strong indication of likely clinically significant disease. It morbid conditions such as cholangitis/cholangiohepati­
is inappropriate to discount these findings in these tis or the presence of extrapancreatic disease that
patients, and important to consider that pancreatic could explain the clinical signs. Therefore, abdominal
disease is, to all indications, common in the sick cat pop­ ultrasonography, carried out by a well‐trained and experi­
ulation and also a common co‐morbid condition with enced operator, is recommended in all cats where there
other diseases. is a clinical suspicion of pancreatitis.
In humans, the use of abdominal computed tomogra­
phy (CT) examination is considered highly useful in the
Diagnostic Imaging
assessment of pancreatic disease. This modality allows
Along with the specialized noninvasive testing methods the assessment of pancreatic architecture, presence and
discussed above, diagnostic imaging is commonly used severity of fibrotic change and detection of both com­
in the assessment of pancreatic disease in the cat. Of the mon inciting causes for pancreatitis in humans (such as
various methodologies available, high‐resolution gallstones) and other co‐morbid diseases. The utility of
abdominal ultrasonography typically has the greatest abdominal CT for the assessment of feline pancreatic
diagnostic yield. It also allows further assessment of disease is much lower than in humans. This is due to
other abdominal organs that may be involved in co‐mor­ the much smaller mass of pancreatic tissue in the cat,
bid diseases, such as the hepatic parenchyma, biliary and less common presence of severe architectural dis­
tree, and intestinal walls. tortions due to fibrosis. Additionally, abdominal CT
Plain abdominal radiography, while commonly used examination of cats typically requires general anesthe­
in cats with suspected abdominal disease, has a very sia, which may be contraindicated in severely unwell
low diagnostic yield in cats with pancreatitis. The pan­ cats and also leads to significant additional cost. CT
creas is not visible on plain abdominal radiographs, and examination has been reported in cats in a small num­
changes commonly seen in dogs with pancreatitis ber of publications; the overall sensitivity and specific­
(“ground glass” appearance, loss of local contrast, wid­ ity were not higher than those seen with less invasive
ening pyloric angle) are infrequent in cats due to the testing such as Spec‐fPL or abdominal ultrasonography,
differing underlying pathology in most cases. While and thus abdominal CT cannot be recommended as a
abdominal radiography has some possible advantages part of the diagnostic approach to pancreatic disease in
in terms of lower cost and greater availability, the very the cat at this time.