Pancreatitis in Dogs and Cats

Pancreatitis in Dogs and Cats
Susan Yohn, DVM, MS, DABVP-Canine/Feline, DACVIM

Pancreatitis is a disease process that affects both dogs and cats; however, there are species differences seen in clinical presentation, possible etiologies, diagnostics and appropriate therapies. In both species, the conclusive diagnosis of pancreatitis can be difficult and management challenging. The goal of this article is to provide a comprehensive overview of pancreatic disease in dogs and cats with discussion, as appropriate, of the species differences.

Pancreatitis refers to infiltration of inflammatory cells into the exocrine pancreatic tissue. Acute and chronic forms are recognized with chronic disease characterized by persistence or relapse of clinical signs, persistent laboratory abnormalities, and development of histopathologic changes in the pancreas including fibrosis and atrophy. Depending on the study referenced, 6% to 10% of cats and dogs have histopathologic signs of pancreatitis at necropsy.

What causes pancreatitis?

The etiology in most cases of pancreatitis is not determined. The most common etiology suspected in dogs is dietary indiscretion, the classic “dog got into the garbage.” The correlation with dietary indiscretion is not usually seen in cats. Other risk factors in the canine include chronic hyperlipidemia, obesity, small breed size, and prior history of GI disease, diabetes mellitus, Cushing’s disease or hypothyroidism. Viral infections (FIP, herpesvirus, calicivirus), chronic hyperlipidemia, hypercalcemia, trauma (high rise syndrome), and prior history of diabetes mellitus and gastrointestinal (GI) or hepatic disease are considered risk factors for pancreatitis in the feline.

Certain drugs can also predispose to pancreatitis. In dogs, potassium bromide, phenobarbital, and certain chemotherapies have been implicated in the development of pancreatic disease. In cats, chemotherapeutics, certain antibiotics and organophosphates have been associated with pancreatitis.

What are the clinical signs of pancreatitis?

Most dogs present with an acute form of the disease. Middle-aged to older dogs (>5 years old) who are overweight are commonly presented to the veterinarian. There may be a higher breed risk for miniature schnauzers, Yorkshire terriers, silky terriers, and miniature poodles. Common clinical canine symptoms include lethargy, anorexia, hunched stance, vomiting (+/- blood), diarrhea (+/- blood), increased respiratory rate and painful abdomen. Physical examination findings are variable with some dogs showing only lethargy and mild abdominal discomfort. More severely affected dogs may be moribund, febrile or severely dehydrated with signs of shock.

Cats tend to present with a more chronic form of pancreatitis. Symptoms may seem acute to the owner, but cats commonly develop pancreatitis in association with other chronic diseases including inflammatory bowel disease and hepatitis. Middle-aged to older neutered domestic shorthaired breed cats are overrepresented. Clinical signs with cats tend to be more nonspecific including lethargy, anorexia and weight loss. Vomiting and diarrhea are less common in cats. Abdominal pain may not be easily identified on physical examination.

It is important to remember that other diseases can present with signs that mimic pancreatitis in both dogs and cats. Acute gastroenteritis, GI obstruction or torsion, pyelonephritis, GI neoplasia and even acute back pain can present with similar clinical symptoms.

What tests are appropriate to diagnose pancreatitis?

Definitive confirmation of pancreatitis in the individual pet may be difficult. No all-typical clinical signs are present in the individual pet. There is no one test that is pathognomonic for pancreatitis except pancreatic histopathology, a test not usually indicated or pursued in the average patient. Diagnosis is based on evaluating a combination of clinical, hematologic, biochemical and imaging findings in both cats and dogs.

Every patient should receive a physical examination and a minimum database including complete blood count (CBC), serum chemistries, urinalysis, pancreatic specific enzymes, abdominal radiographs and/or abdominal ultrasound.

CBC in dogs may show an inflammatory or infectious leukogram. Mild increase in packed cell volume can be seen associated with dehydration. Thrombocytopenia can be seen in dogs with associated coagulopathy or inflammatory destruction of platelets. In cats, the CBC more commonly will show a mild nonregenerative anemia. Neutrophilia without a left shift and lymphocytosis can also be seen in cats associated with more chronic inflammatory disease.

Serum chemistry abnormalities in dogs include azotemia (prerenal and renal); increased liver enzymes (ALP, ALT, GGT, AST); increased bilirubin; increased lipids; hyperglycemia; decreased serum proteins and calcium; and possible sodium, potassium, and chloride changes associated with metabolic acidosis. In cats, increased liver enzymes (ALP, ALT, GGT); increased bilirubin, cholesterol, and glucose; and decreased potassium, calcium, and albumin are the most common biochemical abnormalities seen.  Azotemia may or may not be present in feline patients.

Urinalysis, in both dogs and cats, helps characterize azotemia as renal or prerenal. Urinalysis helps assess for the possibility of primary or associated pyelonephritis. Proteinuria can be seen in dogs with associated pancreatic enzyme damage or antibody complex deposition affecting glomerular tissue.

Pancreatic Specific Enzymes: Classically, elevations in serum amylase and lipase have been used, in cats and dogs, to help diagnose pancreatitis, but they are not specific indicators of pancreatic inflammation. Elevated amylase or lipase can be indicative of pathology in the pet, but it may be associated with gastrointestinal, hepatic, renal or pancreatic disease. If other clinical parameters and laboratory results are consistent with pancreatitis, increases in these enzymes may support that diagnosis. These enzymes usually remain part of most basic chemistry panels.

Trypsin-like immunoreactivity (TLI) is also used clinically to assess the pancreas. Serum TLI is produced only by the pancreatic tissue and is elevated early in dogs and cats with pancreatitis, but the level diminishes rapidly after initial elevation, within 3 days in dogs and within 48 hours in cats. TLI is cleared by glomerular filtration, so it can be increased with renal disease. In both dogs and cats, a clearly increased serum TLI without azotemia is consistent with a diagnosis of pancreatitis, but the diagnosis cannot be ruled out if the TLI is normal.

Pancreatic lipase immunoreactivity (PLI) assays are considered the most sensitive and specific tests used to help diagnose pancreatitis in dogs and cats. The immunoassays are used to quantify lipase exclusively of pancreatic origin. The molecular structure of PLI is different in each species, and species-specific assays are used in the laboratory (canine PLI and feline PLI; abbreviated cPLI and fPLI). There is a wide reported sensitivity range for cPLI assays (21% to 78%) and fPL assays (58% to 100%). This variation reflects differences between study design, population of animals used in each study and severity of disease. The sensitivity of PLI assays may be decreased in more chronic or mild disease because enzyme leakage from the pancreas is diminished. Because the PLI enzyme is specific to the pancreas, the specificity of these assays is high, canine 81% to 100% and feline 67% to 100%. Abnormal species-specific pancreatic lipase results may be consistent with a diagnosis of pancreatitis in the cat or dog, but the results must be interpreted with all other clinical data. Pancreatic inflammation may be primary disease or may be secondary to other systemic illness (acute gastroenteritis, pyelonephritis, cholangiohepatitis or neoplasia).

The originally developed assay for PLI is still available at many labs along with other newer immunoassays that show similar clinical performance. These include the quantitative Spec cPL® for dogs and Spec fPL® for cats. SNAP cPL® and SNAP fPL® are available as rapid in-clinic semi-quantitative immunoassays that are most useful to help rule out pancreatitis in the patient. A normal result for these rapid assays makes pancreatitis less likely. It is important to remember to interpret the results with all other clinical factors considered.

Imaging: In both cats and dogs, abdominal radiographs may show loss of serosal detail with increased opacity in the right cranial abdominal quadrant. Outflow tract duodenum may be displaced ventrally and laterally and may be dilated with plication of the serosal margin. The transverse colon may be displaced caudally. In more chronic pancreatitis, punctate calcification in the area of the pancreas may be seen associated with calcium deposition in saponified peripancreatic fat.

Abdominal ultrasound, along with species specific PLI, is one of the best tools to help in the diagnosis of acute pancreatitis in the dog and cat. The sensitivity of ultrasound is affected by the skill of the person using this tool. Ultrasound findings may include enlarged pancreas with hypoechoic tissue and dilation of the pancreatic duct. Cavitary lesions (abscess, cyst and pseudocyst) may be seen associated with the pancreatic tissue. Other findings may include dilated hypomotile duodenum, biliary tract dilation in the liver, and peripancreatic or diffuse peritoneal fluid. There is a higher sensitivity reported for ultrasound diagnosis of pancreatitis in dogs (90%) compared to cats (35% to 70%). This may reflect the more chronic nature of the disease in cats with fewer acute tissue changes seen at the time of clinical presentation. It is important to remember that other diseases can have identical ultrasound appearance to pancreatitis. Differential diagnoses to consider with ultrasound evaluation include pancreatic neoplasia, pancreatic edema associated with hypoproteinemia or portal hypertension, and enlargement of peripancreatic structures.

What therapies are appropriate to manage pancreatitis in dogs and cats?

Medical treatment for acute pancreatitis in dogs and cats is aimed at restoring adequate tissue perfusion, limiting bacterial translocation and inhibiting the inflammatory process. No studies have evaluated the treatment modalities in dogs or cats with naturally occurring pancreatitis. Initial medical management is often started before a diagnosis of pancreatitis is obtained. Dehydration and hypovolemia are treated with intravenous fluids with electrolyte, calcium and acid base management as indicated by the minimum data base results. Colloids may be indicated in the presence of hypoproteinemia or shock. Insulin therapy may be needed if concurrent diabetes mellitus is present. In cats, stress hyperglycemia may need to be differentiated from diabetes.

Antiemetics (chlorpromazine, metoclopramide, ondansetron or maropitant) and antacids (famotidine, omeprazole) are given for vomiting. Prophylactic antibiotics are indicated in patients with shock, fever, leukocytosis or other evidence of infection or breakdown of the GI barrier such as severe diarrhea with blood.

Analgesia is important in both cats and dogs even if clinical signs of pain are not apparent.  Buprenorphine, oxymorphone and/or fentanyl therapy can be used in both species. Nonsteroidal analgesics can be considered but are present risks of GI ulceration, renal failure and hepatotoxicity especially in patients with severe disease, dehydration or shock.

Many dogs with acute pancreatitis respond to fluid therapy and withholding food and water for 48 hours along with GI supportive management. More aggressive therapy is indicated for dogs that do not respond to minimum supportive care. When a coagulopathy or hypoproteinemia are present, or the patient is clinically deteriorating, fresh frozen plasma may be beneficial to treat the coagulation disorder or hypoproteinemia, and to restore a more normal protease-antiprotease balance. Heparin may be useful in treatment of coagulopathies and improving microcirculation to the pancreas. Cats frequently have combination disease with pancreatitis associated with chronic liver and GI disease. Treatment plans may need to be modified to include simultaneous treatment of liver (Denamarin®, ursodiol) and inflammatory bowel disease (metronidazole, cobalamin and steroids).

Nutritional management is important in the recovery from pancreatitis in both dogs and cats.  In dogs, it has been traditional to withhold food and water for several days with the concern that feeding would continue to induce production of pancreatic enzymes that would make the pancreatitis worse.  Withholding food actually leads to gastrointestinal ileus and villous atrophy.  Significant catabolic deficits, increased susceptibility to GI bacterial translocation, and decreased immune function occur with protein deficits created by fasting.  Withholding food from cats with pancreatitis has not been a traditional recommendation but many cats present with prolonged anorexia and may not offer to eat on their own.  Enteral feeding has advantages over parenteral feeding including stabilization of the GI barrier, improvement in GI motility, decreasing the need for antibiotic therapy, and possibly decreasing hospitalization time.

Once vomiting is controlled, enteral feeding by mouth, placement of an esophagostomy tube, or nasogastric tube in both species is recommended.  Parenteral nutrition or placement of a jejunostomy tube are options to consider if the patient cannot tolerate oral feedings.  Low fat highly digestible protein diets are indicated for dogs with pancreatitis.  In cats, there is no evidence that low fat diets prevent or treat pancreatitis.  Hypoallergenic diets may be indicated in both species if pancreatitis is suspected associated with underlying inflammatory bowel disease.  Oral pancreatic supplementation can be considered and may be helpful by inhibiting pancreatic enzyme secretion.  Addition of appetite stimulants (mirtazapine or cyproheptadine), probiotic supplements, parenteral cobalamin, liver support supplements, or parenteral cobalamin therapy may be indicated in the individual dog or cat patient.

What is the prognosis for pets with pancreatitis?

The prognosis for dogs and cats with pancreatitis is related to the severity of their disease and response to initial therapy. The prognosis for dogs with mild acute pancreatitis is good. Severe or recurrent pancreatitis or dogs with pancreatic abscesses or necrotizing pancreatitis is associated with a more guarded prognosis. Cats usually have a favorable prognosis when presented with chronic pancreatitis. In both species, prognosis is poorer with evidence of multisystem disease (liver disease, renal disease, coagulopathy, diabetes mellitus and peritonitis). Owners need to be aware that recurrence of pancreatitis in both cats and dogs is common after the initial presentation and long-term diet, medication and supplement therapy is often necessary once the pet has been sent home. Death may result for both dogs and cats with pancreatitis if significant complications develop despite supportive therapy. Some owners may need to make decisions for humane euthanasia if cost-prohibitive therapies such as surgery or extended hospitalization are needed or if the patient declines despite supportive care.