Acute Pancreatitis

By Lisa Murphy DACVECC

Acute pancreatitis is a very common syndrome seen in emergency patients, especially dogs. It is also one of the more frustrating diseases to treat. Every case is different although in general carers need to be prepared for their pets to spend several days in the hospital and, in moderate to severe cases, for invasive treatments like the placement of temporary or permanent feeding tubes. 

There are three general types of pancreatitis: acute, recurrent or chronic. Pancreatitis can range in severity from mild/subclinical to severe and even life-threatening with the development of multiple organ failures. 

Pathophysiology

Most cases in dogs and cats tend to be idiopathic although certain dog breeds may be predisposed (miniature schnauzers). Regardless of the inciting cause, pancreatitis stems from the premature activation of trypsin within the acinar cells which leads to the activation of other zymogens. Technically, the body should have many defence mechanisms to avoid the premature activation of trypsin; for example, several factors are needed to activate trypsin and its activation is pH dependent. The final result of this premature activation is auto-digestion and inflammation of the pancreas which can spread to the nearby duodenum and peritoneum. 

Recently in people, it has been proposed that the compensatory anti-inflammatory response syndrome (CARS) (also here) may have a role to play in pancreatitis. If the CARS response is excessive the lack of inflammation can increase susceptibility to secondary infections and pancreatic necrosis, which is much more common in people than dogs and cats.

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Diagnosis 

There are many tests to help us diagnose pancreatitis however typically the less severe the disease is, less the sensitive the test is. 

  • Haematology, Biochemistry:
    • These can be normal in mild cases. They may show significant evidence of organ dysfunction in more severe cases including azotaemia, elevated liver enzymes, anaemia/haemoconcentration and hypoalbuminaemia among others.
    • A low ionised calcium level in cats is reportedly a poor prognostic indicator
  • Serum Amylase/Lipase:
    • Sole use of these measurements for diagnosing pancreatitis is not recommended due to their low sensitivity and specificity.
  • Pancreatic lipase immunoreactivity (PLI):
    • Pancreatic lipase is exclusively of pancreatic origin which means it should have a high sensitivity compared to serum lipase
    • There are two forms of the test; SNAP PLI or Spec PLI. The reference range for normal canine spec PLI is 0-200mcg/l and for cats is 0-3.5mcg/l with values > 400 mcg/l in dogs and 5.4 mcg/l in cats highly suggestive of pancreatitis.
    • Based on histopathology, sensitivity can range from 20% for mild/chronic pancreatitis to 70% for more severe forms.
  • Trypsin-like immunoreactivity (TLI):
    • Has been shown to increase in experimental induction of pancreatitis but decreases within 3 days post induction in dogs and 2 days in cats
    • The sensitivity of TLI for acute pancreatitis is low (36-47%) likely due to the short half-life of trypsinogen
    • It can be increased by other disorders (IBD, gastrointestinal lymphoma, azotaemia)
  • Radiography:
    • Very little use for diagnosing pancreatitis (likely < 30% sensitivity)
    • Common findings include decreased serosal detail in cranial abdomen, displacement of the stomach/duodenum, abdominal effusion and dilation of bowel loops adjacent to the pancreas.
  • Ultrasound:
    • A sensitivity of almost 70% in dogs and 11-70% in cats for pancreatitis depending on the degree of pancreatitis and skill of the person doing the ultrasound.
  • Fine needle aspiration (FNA):
    • Relatively non-invasive however focal lesions may be missed and an experienced practitioner is required.
    • A recent study suggested the risk of pancreatitis post pancreatic biopsy is low.  

Clinical Presentation

Signs associated with acute pancreatitis are variable and non-specific
Common findings in dogs: anorexia, vomiting, abdominal pain, depression, diarrhoea and pyrexia
Common findings in cats: lethargy, anorexia, dehydration;  vomiting and abdominal pain less likely 

Treatment

There is no specific treatment for pancreatitis, instead focus must be on controlling the symptoms and any possible underlying disease.

The basic guidelines for supportive care are as follows:

  • Fluid resuscitation:
    • Severe acute pancreatitis is a classic cause of shock, especially in dogs, due to systemic vasodilation (distributive) and hypovolaemia (due to extravascular fluid shifts, gastrointestinal fluid loss and reduced fluid intake).
    • Some patients require the use of inopressor agents (if available)
  • Use of fresh frozen plasma (FFP) is controversial due to concerns it could worsen inflammation:
    • One veterinary study evaluating FFP in veterinary cases of pancreatitis showed a higher mortality although the study may have some bias as it was retrospective.
    • Similar studies in human patients with pancreatitis have failed to document a benefit of FFP use.
    • At this time, there is insufficient evidence to recommend routine use of FFP in pancreatitis cases unless there is a concurrent coagulopathy.
  • Routine calcium supplementation in cases of hypocalcaemia is not recommended unless the animal is showing symptoms of tetany due to risks of exacerbating free radical production.
  • Anti-emetics and antacids
  • Adequate analgesia
    • Severe acute pancreatitis can be extremely painful and an aggressive and responsive pain management protocol is needed.
    • NSAIDs should typically be avoided since many of these patients are anorexic and experiencing vomiting.
    • No proven benefit associated with steroid use.
  • Nutrition
    • It is now recommended to institute enteral feeding within 24 hours of hospitalisation. Perceived benefits are improvements in gastrointestinal mucosal health, and decreased likelihood of clinically significant bacterial translocation from the GI tract into the systemic circulation. Enteral nutrition is thought to have fewer complication rates when compared to parenteral nutrition.
    • No significant differences in outcomes in human patients between nasojejunal and nasogastric feeding in pancreatitis so pre-jejunal feeding is likely an acceptable enteral route.
    • For more on nutrition in acute pancreatitis see this podcast episode - the episode is several years old but remains relevant.
  • Routine use of antibiotics is only recommended in cases of necrotising pancreatitis or those with a documented infectious cause.
  • Surgical indications may include those who are failing medical management, those with infected pancreatic necrosis and those with extra-hepatic bile duct obstruction.
    • However human studies of those with necrotising pancreatitis have failed to conclusively prove a benefit to pursuing surgery over less invasive options (transcutaneous CT-guided drainage, endoscopic trans-enteric drainage).
    • To the author’s knowledge, there are no published studies evaluating surgery in pancreatitis in dogs and cats. An abstract presented at ACVIM in a small cases series of dogs did not show improved outcome in cases of necrotising pancreatitis which were treated surgically versus medically.

References: 

Swift, N.C., Marks, S.L., MacLachlan, N.J. and Norris, C.R., 2000. Evaluation of serum feline trypsin-like immunoreactivity for the diagnosis of pancreatitis in cats. Journal of the American Veterinary Medical Association, 217(1), pp.37-42.

Xenoulis, P.G., 2015. Diagnosis of pancreatitis in dogs and cats. Journal of small animal practice, 56(1), pp.13-26.

Cridge, H., MacLeod, A.G., Pachtinger, G.E., Mackin, A.J., Sullivant, A.M., Thomason, J.M., Archer, T.M., Lunsford, K.V., Rosenthal, K. and Wills, R.W., 2018. Evaluation of SNAP cPL, Spec cPL, VetScan cPL Rapid Test, and Precision PSL Assays for the Diagnosis of Clinical Pancreatitis in Dogs. Journal of Veterinary Internal Medicine.

Jensen, K.B. and Chan, D.L., 2014. Nutritional management of acute pancreatitis in dogs and cats. Journal of veterinary emergency and critical care, 24(3), pp.240-250.

Cerón, J.J., Eckersall, P.D. and Martínez‐Subiela, S., 2005. Acute phase proteins in dogs and cats: current knowledge and future perspectives. Veterinary Clinical Pathology, 34(2), pp.85-99.

Pratschke, K.M., Ryan, J., McAlinden, A. and McLauchlan, G., 2015. Pancreatic surgical biopsy in 24 dogs and 19 cats: postoperative complications and clinical relevance of histological findings. Journal of Small Animal Practice, 56(1), pp.60-66.

Tvarijonaviciute, A., García‐Martínez, J.D., Caldin, M., Martínez‐Subiela, S., Tecles, F., Pastor, J. and Ceron, J.J., 2015. Serum paraoxonase 1 (PON1) activity in acute pancreatitis of dogs. Journal of small animal practice, 56(1), pp.67-71.

Webb, C.B. and Trott, C., 2008. Laparoscopic diagnosis of pancreatic disease in dogs and cats. Journal of veterinary internal medicine, 22(6), pp.1263-1266.