"Garbage gut": acute pancreatitis
HALIFAX, NS – When animals present to the emergency room with GI symptoms, pancreatitis is one of the diseases that must be considered. Technicians often can get a hint from the history, (“He got into the garbage last night”), but due to the variability of the disease, it is important for technicians to recognize the signs in order to catch problems early and help guide therapy, explained David Liss, RVT, VTS (ECC), speaking at the Atlantic Provinces Veterinary Conference.
The pancreas is a glandular organ in the cranial abdomen, attached to the wall of the duodenum and lying between the duodenum and the stomach on the right side of the body. It has right and left lobes; the right lobe extends down the duodenum and the left lobe angles medially, underneath the body of the stomach.
The major function of the exocrine pancreas (endocrine pancreas secretes insulin) is to store and then releases enzymes for digestion of nutrients. Dogs have two pancreatic ducts that release enzymes, whereas cats only have one duct.
Acute pancreatitis, which is seen relatively frequently in the veterinary hospital, results from an inappropriate activation of the typically inactive enzymes, called zymogens, inside the pancreas. Pancreatic enzymes digest tissue, and thus are relatively toxic to the body if activated. Pancreatic inflammation, cellular edema, and necrosis typically occur. Once the pancreatic cells rupture, they leak active pancreatic enzymes in the peritoneum and systemic circulation. This causes widespread systemic inflammation causing a SIRS syndrome. In rare cases, these pancreatic enzymes and systemic inflammation can cause coagulation cascade activation and multiple organ dysfunction and death.
Severe acute pancreatitis exists when systemic signs of pancreatitis occur with multiple organ involvement or dysfunction. Pancreatic necrosis, abscesses, or pseudocysts are typically found in these patients.
History/Physical examination
Due to the variability of the disease, some patients remain in a subclinical phase, or have mild GI signs such as anorexia, vomiting, and/or diarrhea. Mr. Liss said that gluttony, and the consumption of a fatty meal, or “garbage gut”, are thought to be associated with pancreatitis. The signs may mimic an upper GI obstruction, so it is important to carefully evaluate the patient and perform timely diagnostic tests.
Patients will often present with dehydration, fever, icterus, abdominal pain, and lethargy. They may also show signs of shock due to pain, such as tachycardia, tachypnea, weak pulses, hypotension, and mental dullness.
Diagnostic testing
Radiography and ultrasonography
Abdominal radiography is recommended in patients suspected of having acute pancreatitis to help rule out upper GI obstruction. Findings may include loss of detail in cranial abdomen, displacement of the stomach to the left, or the duodenum to the right or ventrally. However, in one large study involving patients that died due to pancreatitis, only one quarter had radiographic changes. Ultrasonography is a useful diagnostic test if the technician is skilled, and it is more sensitive (less false negatives) than radiography. Ultrasonographic findings include an enlarged pancreas, hypoechoic pancreatic centre, hyperechoic area surrounding the pancreas (peripancreatic fat necrosis), and effusion surrounding the pancreas.
Laboratory analysis
All patients presenting to the emergency room will benefit from a minimum database, and a complete blood count and biochemical profile.
Common findings include inflammatory leukogram, anemia and thrombocytopenia (if patient is in DIC), elevated PCV from dehydration, hemoconcentration, elevated amylase and lipase levels, azotemia, hyperglycemia, hypoglycemia, hypercholesterolemia, elevated liver enzymes and hyperbilirubinemia, and hypocalcemia.
It is important to note that elevated amylase and lipase are not highly correlated as diagnostic of pancreatitis because tests run on typical in-house biochemical analyzers are not pancreas-specific. Also, normal amylase/lipase levels do not rule out pancreatitis. Mr. Liss explained that since the pancreas is quite near the bile duct, inflammation and swelling can cause an extrahepatic bile duct obstruction. Thus liver enzymes and markers of biliary tree disease may be elevated. Hyperglycemia is a common finding and is either a marker of stress or development of diabetes mellitus.
Pancreatic markers/inflammatory markers
C-reactive protein is used in humans to determine severity of pancreatitis. The trypsin-like immunoreactivity (TLI) and pancreatic lipase immunoreactivity (PLI) tests are both pancreas-specific tests and are used in the diagnosis of pancreatitis. While the TLI test is useful in diagnosing exocrine pancreatic insufficiency, its sensitivity and specificity with pancreatic inflammation and dysfunction are low. Therefore, the PLI is the preferred test. It reports pancreas-specific lipase, which is chemically unique from other lipases, and is unaffected by renal failure. It is still recommended to follow up a positive snap test with a spec-CPL measurement. The spec-CPL has greater accuracy for canines, than the fPLI test does for felines.
Treatment
Fluid therapy
Patients with pancreatitis are typically dehydrated, and potentially hypovolemic. If there are any perfusion deficits present, boluses of balanced crystalloid solutions should be used. Once perfusion is restored, rehydration and treatment of ongoing losses can occur. Typically a crystalloid solution that is isotonic and contains some trace electrolytes is used. Potassium supplementation may be used to treat losses.
Anti-emetics
Patients that are vomiting are typically treated with anti-emetics to prevent further vomiting and fluid loss.
Pain management
Pain assessment and scoring should be used to assess pain severity. Pure mu opioids are best at achieving analgesia in these patients. Mr. Liss said that he has often found that pure mu opioids need to be given above a buprenorphine dose for “breakthrough” pain.
Nutrition
Historically, patients were not fed at all during the course of pancreatitis. The addition of food to the stomach induces the pancreas to work, and secrete digestive enzymes. So post-pyloric feeding is often indicated, accomplished with a jejunostomy tube. Typically a J-tube is fed through a gastrostomy tube, however, these require anesthesia for surgical or percutaneous placement. Diets fed through a J-tube need to be easily digestible and several elemental diets exist (Clinicare®, Vivonex®, Enteral Care®). Cats also require different combinations of fat, protein, and carbs so Feline Clinicare® may be the better option for them. In cats, pre-pyloric feeding is often well tolerated. Mr. Liss said that in his experience, nasogastric tubes in dogs are typically well tolerated, and it is advisable to use the enteral route whenever possible. If the patient does not tolerate enteral feedings, the parenteral route may be used. Indications for parenteral nutrition include intractable vomiting, large volume raging diarrhea, or complications with tube placement. Patients with pancreatitis are typically in a catabolic state and thus partial parenteral nutrition is probably not enough; total parenteral nutrition (TPN) is often required. Mr. Liss said that this is an expensive and technically demanding nutritional intervention, requiring 24-hour care and central line placement. While there are many complications with TPN, it can be a rewarding treatment if successful.
Rare complications
With severe pancreatitis, complications such as DIC and multi-organ failure can result. Careful screening for these problems can help catch them before they have progressed. DIC is a difficult syndrome to treat and is characterized by early hypercoagulability and subsequent hypocoagulability. Fresh frozen plasma and anticoagulants are typically used to treat DIC. Multi-organ failure can include liver failure, renal failure, pulmonary dysfunction (acute respiratory distress syndrome), or GI dysfunction. Gut necrosis can lead to bacterial translocation and sepsis, despite most uncomplicated pancreatitis being considered a non-infectious disease. Careful nursing monitoring of the hematologic, renal, and GI systems can help prevent these problems from occurring.
Conclusion
Mr. Liss concluded by saying that pancreatitis has a favourable outcome if treated early and aggressively. There is no definitive treatment, and most treatments are symptomatic. Early aggressive nutrition can help provide a positive outcome. Careful monitoring of vital signs and organ systems can catch problems early and help guide therapy. CVT
