PANCREATITIS IN DOGS

Gastroenterology & Digestive Diseases

Pancreatitis is an inflammatory condition that affects the pancreas. It can be acute or chronic and develops when there is activation of pancreatic enzymes, such as trypsin, which results in autodigestion of the pancreas. Acute and chronic pancreatitis can be mild or life threatening.

Mild acute pancreatitis is associated with pancreatic edema and is often self-limiting. Most affected dogs recover quickly, some without treatment. Severe acute pancreatitis is a progressive illness and is often associated with numerous metabolic consequences. Aggressive medical care is frequently necessary.

Chronic pancreatitis is often referred to as recurrent or smoldering pancreatitis. Mild chronic pancreatitis is associated with minimal pancreatic damage. Severe chronic pancreatitis is a progressive disease, and significant pancreatic damage and destruction results in pancreatic enzyme insufficiency.

Complications associated with pancreatitis can be mild or serious. In the case of severe acute pancreatitis, metabolic complications are common and include hypothermia, peritonitis, DIC, sepsis, acute renal failure, hyperglycemia, cardiac arrhythmias, biliary obstruction, parenchymal liver disease, and multi-organ failure. Further complications include pancreatic abscess, chronic relapsing pancreatitis or diabetes mellitus.

DIAGNOSIS OF PANCREATITIS IN DOGS

ETIOLOGY AND RISK FACTORS

• Causes - The cause of pancreatitis is often unknown and the pathogenesis is poorly understood. Most cases are considered idiopathic but gastrointestinal disease, endocrine abnormalities, recent abdominal surgery and some drugs may play a role in the development of pancreatitis. Some drugs include azathioprine, L-asparginase organophosphates. Although corticosteroids have long been implicated in the development of pancreatitis, recent studies question the role of corticosteroids. Corticosteroids can worsen acute disease.
  
  Pancreatitis is thought to be initiated as a cellular event that occurs due to pancreatic acinar cell membrane damage from the activation of trypsin. Once trypsin is activated, it in turn activates other pancreatic enzymes, ultimately resulting in pancreatic autodigestion. Once pancreatitis has begun, its progress is due to release of factors such as free radicals, activated enzymes, inflammatory mediators, activated complement, and endotoxins.
  
  Mild pancreatitis can develop into severe necrotizing pancreatitis if the microcirculation of the pancreas is impaired due to pancreatic edema.
• Risk factors
• Age - Most affected dogs are middle-aged or older
• Breed/genetics - The most commonly affected breed is the schnauzer, possibly due to the breed's propensity toward hyperlipidemia
• Sex - No known risk
• Geographic/environmental - No known risk
• Other medical disorders - There are a variety of risk factors, such as obesity, long-term intake of a high fat diet, ingestion of a very fatty meal, hyperlipidemia, hyperadrenocorticism, diabetes mellitus, hypothyroidism, idiopathic hyperlipidemia of miniature schnauzers, parvovirus, hypercalcemia (over 15 mg/dl), abdominal trauma, abdominal surgery or pancreatic neoplasia.

• Prevention - Prevention of pancreatitis is difficult since most cases are idiopathic. Some preventative measures may include weight loss for obese pets, and careful dietary restriction from high fat meals and table scraps for pets at risk.

HISTORY AND CLINICAL SIGNS

• Species affected - Dog and cat
• Presenting signs and historical problems - The most common signs of pancreatitis includes vomiting, abdominal pain, anorexia and lethargy. Abdominal pain may be associated with panting, restlessness, trembling and praying position. Occasionally diarrhea, fever and weakness can also be seen.

PHYSICAL EXAMINATION FINDINGS

• General
• Attitude - Mental status varies. Most dogs are depressed but some may be profoundly weak, even comatose
• Body condition - Many affected animals are obese.
• Vital signs - Fever and tachycardia may be present
• Mucous membranes - Mucous membranes may be icteric
• Hydration status - Due to vomiting and anorexia, many dogs are dehydrated.
• Head and neck - Unremarkable
• Eyes - Sclera may be icteric
• Oral cavity - Mucous membrane may be brick red and tacky, due to dehydration.
• Thorax (cardio-pulmonary) - Tachycardia may be present in response to abdominal pain. Tachypnea from secondary respiratory involvement.
• Abdomen (gastrointestinal/urinary) - Abdominal palpation may reveal abdominal tenderness, splinting or pain, especially in the cranial abdomen. In some cases, a mass effect may be palpated in the right cranial abdomen.
• Reproductive system - Unremarkable
• Lymph nodes - Unremarkable
• Integumentary system - Dehydration is a common finding
• Neurologic examination - Mental status may vary. Most cats are depressed and lethargic but some may be profoundly weak or even comatose. Neurologic examination is often normal.
• Musculoskeletal examination - Weakness and trembling may be present.

DIAGNOSTIC STUDIES

• Clinical laboratory tests
• CBC - The CBC may reveal leukocytosis with neutrophilia. A left shift may be present. If severe necrosis, peritonitis, sepsis or endotoxemia is present, neutropenia with a degenerative left shift may be seen. The hematocrit is often elevated due to dehydration.
• Serum biochemical tests - Biochemical test results vary, depending on the severity of disease and underlying or concurrent illness. Results may reveal:
  ↑ Bilirubin (due to biliary obstruction)
  ↑ Alkaline phosphatase (due to cholestatic changes)
  ↑ Alanine aminotransferase (due to hepatocellular damage)
  ↑ BUN, creatinine (due to dehydration, hypovolemia or acute renal failure)
  ↑ Glucose
  ↓ Calcium
  ↑ Triglycerides
  ↑ Cholesterol
  
  Amylase and lipase - Both tests are unreliable for the diagnosis of pancreatitis. Values classically are expected to be increased, but clinically values are quite variable. Abdominal fluid amylase or lipase may be significantly increased.
• Urinalysis - Urinalysis is often normal but if renal failure is present, the specific gravity is often submaximally concentrated. If the specific gravity is over 1.025, there is adequate renal tubular function.
• Coagulation profile - If DIC is suspected, activated partial thromboplastin time, one stage prothrombin time and activated clotting time may be prolonged. Thrombocytopenia, decreased fibrinogen and increased fibrin degradation products may be detected
• Serology/immunologic tests - Trypsin-like immunoassay (TLI) can be performed to detect an increase in the levels of circulating trypsinogen and trypsin. These enzymes are often elevated early in acute pancreatitis, but values decline rapidly.
  
  Canine pancreatic lipase immunoreactivity (cPLI) measures specific serum lipase from the pancreas. This test appears to have good diagnostic accuracy. Currently the availability of this test is limited.
• Diagnostic imaging
• Radiographs (thoracic/abdominal) - Abdominal radiographs often reveal a loss of detail, especially in the right cranial quadrant. Radiographs may also reveal displacement of the descending duodenum to the right and the pyloric antrum to the left. Sometimes, a mass effect may be appreciated. Abdominal radiographs may also reveal gastric distention. Thoracic radiographs may reveal pulmonary edema or pleural effusion as a complication
• Contrast radiography - A barium series may be performed to rule-out intestinal foreign body. In pancreatitis, the transit time for the barium is delayed.
• Ultrasound (abdominal) - Abdominal ultrasound can be very helpful. If pancreatitis is present, the pancreas appears irregular and enlarged. There may be a mottled or decreased echogenicity of the gland and there may be effusion surrounding the pancreas. An ultrasound-guided fine needle aspirate will show suppurative inflammation. A pancreatic abscess can be diagnosed through abdominal ultrasound.
• Pathology
• Biopsy/histopathology - Pancreatic biopsy is the best way to confirm the diagnosis of pancreatitis but is rarely performed.

DIAGNOSIS AND PROGNOSIS

• Differential diagnosis - Diseases similar to pancreatitis include:
• Pyelonephritis
• Biliary tract obstruction
• Intestinal obstruction
• Gastrointestinal neoplasia
• Diabetes mellitus
• Hemorrhagic gastroenteritis
• Hepatitis
• Parvovirus
• Peritonitis
• Prostatitis
• Pyometra
• Feline infectious peritonitis
• Toxoplasmosis
• Recommended tests - CBC, biochemical profile, urinalysis, abdominal radiographs and abdominal ultrasound.
• Summary of diagnostic criteria - Pancreatitis is often diagnosed based simply on either elevated amylase and/or lipase levels. Unfortunately, this is not always the most accurate way to confirm the diagnosis. Amylase and lipase can be elevated due to pancreatitis, as well as in gastrointestinal, hepatic and neoplastic disease. Enteritis is known to elevated amylase. High doses of corticosteroids can elevate lipase levels artificially.
  
  When using enzyme levels to help confirm the diagnosis, both amylase and lipase should be evaluated. Avoid using only one of these values. Typically, amylase and lipase elevations due to non-pancreatic disease do not exceed two to three times normal. Although the degree of elevation can help differentiate between pancreatic and non-pancreatic disease, it does not correlate with the severity of the pancreatitis nor help with prognosis.
  
  TLI reveals elevated trypsinogen but must be measured very early in the disease. Abdominal radiographs often reveal a loss of detail and abdominal ultrasound reveals characteristic changes described above.
• Prognosis - Most animals with pancreatitis respond to therapy and recover, but some cases may become life-threatening. Complications can develop. Initially, a fair-to-guarded prognosis should be given. If complications such as septic shock, renal failure or DIC develop, a poor prognosis should be given.

TREATMENT OF PANCREATITIS IN DOGS

TREATMENT PRINCIPLES

Treatment for pancreatitis varies depending on the severity of the disease. Most animals respond to medical therapy, but sometimes surgical exploration is indicated.

INITIAL/HOSPITAL THERAPY

• Medical management - Medical treatment varies depending on the severity of the pancreatitis. Cases of mild pancreatitis are often treated as outpatients with subcutaneous fluids and antiemetics. Severe pancreatitis requires hospitalization and includes the following:
• Intravenous fluids are the mainstay of therapy. Initially, replacement fluids are used to correct dehydration. Potassium is often supplemented in the fluids. Avoid the use of sodium bicarbonate since this can worsen hypocalcemia.
• If hypoalbuminemia is present, hetastarch may be used but should be used with care since it can prolong bleeding times.
• Plasma can be used in severe fulminant pancreatitis. Fresh frozen plasma supplies necessary macroglobulins, which will bind with the circulating activated enzymes. These enzymes are responsible for the autodigestion of the pancreas, and reducing their levels is an important part of treatment. Some clinicians recommend administering 50 to 250 mls of plasma per day until the dog recovers.
• Antiemetics are indicated for the control of perfuse vomiting. Anticholinergic agents are contraindicated because they cause GI ileus. Chlorpromazine, metoclopramide or odanstron should be considered. In severe cases no agent may be helpful.
• Analgesics are recommended to treat abdominal pain. Commonly used analgesics include butorphanol (0.1 to 0.4 mg/kg t.i.d. to q.i.d. SC, IM or IV) or buprenorphine (0.005 to 0.02 mg/kg b.i.d. to q.i.d. IM or IV).
• The use of antibiotics is controversial. Although of no benefit in treating pancreatitis, antibiotics have been recommended to prevent or treat secondary sepsis. Commonly used antibiotics include ampicillin (20 mg/kg t.i.d. IV) or cefazolin (20 mg/kg t.i.d. or q.i.d. IV).
• Glucocorticoids should be avoided unless used in the treatment of septic shock.
• Other therapies such as heparin for DIC, antioxidants, acid blocking drugs, and oral pancreatic enzymes have been suggested by some but these are unproven in benefit.

• Dietary restriction - Feeding dogs with pancreatitis is controversial. Previously, resting the pancreas by not feeding the dog for up to three days has been recommended to prevent pancreatic secretion. Recent research indicates that dogs with pancreatitis benefit from being fed a bland diet as soon as vomiting has ceased. Initially, dogs should be fed a carbohydrate rich diet with limited fat and protein, such as rice, pasta or prescription bland diets. In some dogs, feeding tube placement may be required if the animal that has not eaten in more than four days or is deemed to be in a significant catabolic state. Jejeunostomy tube placement should be considered in the vomiting patient.
• Surgical management - Although uncommon, surgical intervention may be necessary and is indicated in septic peritonitis, pancreatic abscess or if prolonged biliary obstruction is present. Surgical intervention is also recommended when the diagnosis is questionable or for placement of a jejeunostomy feeding tube.

LONG - TERM/HOME THERAPY

After recovery, dogs may need to be fed a bland diet for several days to several weeks. Antibiotics and/or analgesics may be continued for a period of time.

FOLLOW-UP CARE

Affected animals should not be fed high fat diets nor given fatty table scraps. Obese animals can benefit from a weight loss program.