Pancreatitis (Proceedings)

The disease(s)

Unfortunately, we don't really know how common clinically relevant pancreatitis really is in our feline patient population. Based on necropsy studies, pancreatic inflammation may be found in anywhere from <1% to 67% of cats, which is obviously an enormous range. In addition, it is not clear that all pancreatic inflammation is clinically important. However, anecdotal evidence suggests that pancreatitis is a relatively under-diagnosed problem in the clinical patient population (which is also my opinion).

Cases of feline pancreatitis are often classified as acute, chronic, or chronic active based primarily on histopathologic findings. Acute pancreatitis is generally characterized by neutrophilic inflammation or necrosis without evidence of permanent structural changes. The chronic form is characterized by predominantly lymphocytic inflammation and permanent changes such as fibrosis and atrophy. and I actually do use this scheme as well. When characteristics of both are present, the term chronic active pancreatitis is often used.

It is still not clear whether these different classifications reflect different eitiologic origins, or are different phases of one disease process. Actually, no specific underlying cause is identified in a majority of feline pancreatitis cases, regardless of type. Infectious diseases such as Toxoplasma, and certain fluke infestations have been implicated in some cases. It is also likely that some of the risk factors important for people and dogs, such as trauma, ischemia, or certain medications would also be important in cats. One key difference between cats and other species is that there does not seem to be a clear association between dietary fat content or inherent lipid disorders and development of pancreatitis.

There is an association between feline pancreatitis, inflammatory bowel disease, and cholangitis (+/- hepatic lipidosis), but no specific cause & effect relationship has been worked out. Nonetheless, cats with either IBD or cholangitis should be considered at risk for development of pancreatitis. Also, because these conditions are such common co-morbidities, and because they do have significant implications for therapeutic management, any diagnostic plan for feline pancreatitis should also take these diseases into account.

Clinical presentation

One of the things that makes feline pancreatitis such an enigma is that there are no particularly characteristic or specific clinical signs and the clinical course can range from mild and subclinical to severe and life threatening. In general, chronic pancreatitis is more likely to present with a waxing and waning course of relatively mild clinical signs whereas acute pancreatitis is more likely to be associated with moderate to severe clinical disease.

It appears that cats of any age breed or sex can be affected and unlike dogs, cats are as likely to be underweight as overweight. The most common clinical signs identified are also non-specific, including partial or complete anorexia, lethargy, and dehydration. Other clinical signs or physical examination abnormalities that may be present include vomiting, weight loss, abdominal pain, hypothermia, diarrhea, tachypnea or dyspnea, icterus, or a cranial abdominal mass. While vomiting and abdominal pain are reported to occur much less frequently in cats with pancreatitis compared to dogs, there is certainly a valid concern that abdominal pain in cats has been unrecognized or under-reported in the past. In very severe cases, there may be evidence of a severe systemic inflammatory response which could include evidence of hemostatic disturbances, shock, or even multiple organ failure.

Diagnosis

As discussed above, the diagnosis of pancreatitis can be very challenging and best results are probably obtained by collecting information from a variety of sources and adding up the supportive evidence for pancreatitis, while attempting to rule out other appropriate differential diagnosis (e.g. pancreatic neoplasia) and evaluating for common co-morbid conditions (e.g. IBD, cholangitis).

Clinical pathology

A serum chemistry, CBC, and urinalysis can provide so supportive evidence of pancreatitis or other concurrent diseases, but there are no specific findings that can confirm the diagnosis. These tests can also be normal in some cases, even when there is a clinically significant pancreatitis. Hematologic abnormalities, if present, might include a non-regenerative anemia (likely reflective of chronic inflammatory disease) and either leukocytosis or leucopenia. Common biochemical abnormalities include elevations in ALT, ALP, and T Bili (although these might also reflect concurrent hepatic disease). Some patients also have azotemia (pre-renal or renal), low albumin levels (probably due to inflammation or GI or hepatic disease), high BG (occasionally permanent – i.e. development of diabetes mellitus), or electrolyte abnormalities such as hypokalemia and hypocalcemia. Cases with a confirmed ionized hypocalcemia may have a poorer prognosis.

Amylase and lipase are still commonly reported on many serum biochemical profiles, but likely have little clinical value for confirming or ruling out pancreatitis in cats.

Infectious disease testing

For cats with a compatible environmental or medical history of exposure, testing for Toxoplasma gondii or empiric treatment for pancreatic and liver flukes may be warranted.

Feline Pancreatic Lipase Immunoreactivity (FPLI)

This test has proven to be exceptionally valuable in helping to support the diagnosis of feline pancreatitis. However, it is not perfect and there are still a relatively high percentage of chronic or mild pancreatitis cases that might not be detected by relying on this assay alone. There are also a few cases in which pancreatic inflammation might be present but related to more serious underlying disease such as a pancreatic neoplasia, so I rarely advise relying on the fPLI alone.

Diagnostic imaging

Abdominal radiographs, ultrasound and CT have all been used for evaluation of feline pancreatitis. Unfortunately, radiographs lack both sensitivity and specificity for diagnosing pancreatitis in cats. Ultrasound can be useful, but stringent criteria should be used for evaluation and interpretation of findings. There are a number of suggestive changes that can be present in cases of pancreatitis, but in the end it is still important to recognize that no imaging study can provide a definitive diagnosis.

Biopsy

Histopathology is still the only way to be certain of the diagnosis. Unfortunately, obtaining samples involves relatively invasive and expensive procedures. It is also still possible to have false negative results in cases of very localized disease. The other issue is that it can be difficult to interpret the clinical significance of observed histopathologic changes.

Other

Because concurrent IBD and cholangitis are so common in cases of feline pancreatitis, any workup for pancreatitis should also include some assessment of the GI tract and liver. Imaging tests such as ultrasound will help with this, and if biopsies of the pancreas are obtained, then samples should also be taken from the liver and GI tract. In addition to imaging and histopathology, however, consideration should also be given to acquiring bile for culture and sensitivity and testing for serum folate and cobalamine levels (+/- TLI).

Treatment options

Fluid, electrolyte and acid-base support

Dehydration is one of the most commonly reported physical examination finding in cats with pancreatitis. These cats often have inadequate fluid intake and the problem may be exacerbated by excess or ongoing losses through the GI tract if the patient is vomiting or has diarrhea, and in some cases with significant hypoalbuminemia or vasculitis, there may also be some 3rd spacing. Because maintenance of perfusion to the pancreas is thought to be crucial, it is very important to address any deficits relatively rapidly if possible. This will also likely help make the patient feel better.

Colloidal support (e.g.hetastarch) may be indicated in cases with significant hypoproteinemia. There has not been any demonstrated benefit from administration of plasma, but there might be certain circumstances (e.g. coagulopathy, severe hypoalbuminemia with GI ileus) where a plasma transfusion might be indicated

Any electrolyte or acid-base abnormalities that are identified should be monitored and corrected. In many cases this is accomplished by restoring normal volume/hydration, but if abnormalities are severe or persist after fluid deficits have been replaced, then more direct correction may be required.

Nutritional support

Due to a concern about the potential development of hepatic lipidosis in cats, nutritional support tends to be more aggressive than for dogs. In cats that are not vomiting, enteral feeding should be attempted and feeding tubes may be utilized to assist this process relatively early in the course of treatment. In cases where vomiting cannot be controlled, placement of a jejunostomy tube allows enteral feeding while still avoiding pancreatic stimulation. In cases where this is not an option, parenteral nutrition should be considered.

Symptomatic therapy

Antiemetic therapy is indicated for cats that demonstrate clinical signs of vomiting or nausea. Ondansetron and maropitant are both reasonable options. Some authors have suggested that metoclopramide be avoided due to limited effectiveness and a potential for decreasing splanchnic perfusion. An alternative argument is that this medication might help promote gastric emptying and is probably safe in cases where blood pressure and hydration status are normal.

If gastric or intestinal bleeding is documented or suspected, proton pump inhibitors or H2 histamine receptor antagonists may be used.

Appropriate analgesia is another important consideration in cases of feline pancreatitis. Opioids at standard analgesic doses can provide good pain control in the majority of cases. I will often give at least one dose of an opioid on a trial basis even in cases where I am not sure that the patient is really painful. If an animal is truly non-painful, then opioids should be discontinued since they do have the potential to cause or exacerbate GI ileus.

Surgery

Surgical exploration may be performed in some cases to collect biopsy specimens for diagnostic purposes. Surgical treatments may be indicated for cases in which an abscess or pseudocyst is identified, or in which there is evidence of complete biliary obstruction.

Other medications to consider

     • Steroids are probably not indicated for the majority of pancreatitis cases, but it may be helpful for some of the common co-morbid conditions such as IBD.

     • Fenbendazole or praziquantal should be used to treat cats in which fluke infestation is considered a probable or likely differential. Clindamycin or other treatments should be considered in cases where Toxoplasma is considered a likely differential.

     • Cobalamine supplementation is recommended for cases with documented low serum levels.