Pancreatitis in dogs is seen with a prevalence of < 1% in the autopsy room. Even clinically, only 1-2% of dogs in referral clinics are diagnosed with pancreatitis. During the last 10-15 years, several studies have shown that pancreatitis is probably much more common. Unfortunately, several other clinical diseases might look quite similar to acute pancreatitis and multi-organ involvement is not uncommon.

So far, no clear correlation between the various histological forms and clinical signs can be established. Rarely, both acute and chronic forms may result in diabetes mellitus. Furthermore, acute pancreatitis might result in shock, disseminated intravascular coagulation and multi-organ failure.

History and Clinical Signs

Commonly no cause of the pancreatitis episode can be found and it is called idiopathic. Rarely, pancreatitis has resulted from trauma (high-rise syndrome, surgery), infectious diseases, lipodystrophy, or an organophosphate intoxication. Other published causes in dogs are hyperlipidemia, dietary problems (dietary indiscretion and obesity) or hereditary forms (miniature Schnauzers, miniature poodle, terriers). Glucocorticoids, azathioprine and other drugs have been linked with pancreatitis in some dogs.

The most common findings are dehydration (97%), anorexia (91%), vomiting (90%) weakness (70%) and abdominal pain (58%). Respiratory signs (dyspnoea, tachypnoea) are likely due to pain, pleural effusion or a thromboembolic event. Other clinical signs such as diarrhoea, icterus or temperature abnormalities (hypo- or hyperthermia) are found in less than 50% of dogs with acute pancreatitis. Clinical signs are commonly acute. However, in chronic forms of pancreatitis there will be a recurrent flare-up of symptoms.

Diagnosis

The clinician should always have a suspicion of pancreatitis in animals with nonspecific signs as mentioned above - i.e., in all dogs with nonspecific symptoms. In a vomiting dog or a dog with abdominal pain, the work-up must try to differentiate if the symptoms arose due to primary gastrointestinal disease or secondary to other causes of vomiting or abdominal pain. Routine haematology, biochemistry, and pancreatic specific assays along with diagnostic imaging are the most useful tests. Since there is no test that is highly sensitive or specific, a combination of tests is commonly needed to make an informed diagnosis of pancreatitis. The chemistry profile will show mild increases in liver enzymes (ALT, ALP, GLDH) and bilirubin (seen in 50-70% of cases), which is probably due to the simultaneous occurrence of hepatobiliary disease. Azotaemia is commonly seen in animals that are also dehydrated. Hyperglycaemia (seen in 50-60% of cases) may be stress induced, or rarely due to diabetes mellitus. Sometimes, hypocalcaemia can be seen in cases with saponification of abdominal fat.

Haematological results are nonspecific and mild. Non-regenerative anaemia due to a chronic disease is seen in 55% of cases. Leucocytosis with a left shift is seen in severe cases. In animals with marked pancreatitis, a regenerative or even degenerative, left-shift neutrophilia can be found. Dogs might also have abnormalities on a coagulation panel.

Mild elevations in amylase and lipase are commonly seen in animals with other gastrointestinal problems, azotaemia or corticosteroid administration. In general, only a three-fold increase is considered sensitive enough to diagnose canine pancreatitis. It must be remembered that a proportion of dogs with pancreatitis might also have normal amylase and/or lipase results. Amylase and lipase has a sensitivity of 13-73% and 17-62%, respectively, depending on various studies. In some studies, results above the upper reference limit were considered abnormal, while others used a two- or even three-fold increase as indicative of pancreatitis, making comparison difficult.

Analysis of trypsin-like immunoreactivity (TLI) is species specific. While TLI is pancreas specific and in animals with exocrine pancreatic insufficiency (EPI) this measurement is the test of choice, it is not sensitive or specific enough in dogs to diagnose acute pancreatitis. This is most likely because TLI rises quite late in the course of pancreatitis or might already have returned within normal limits when the animal is presented to the veterinarian.

Recently, an enzyme-linked immunosorbent assay (ELISA) was developed and validated to quantitatively measure serum concentrations of canine pancreatic lipase (PL). It is a sensitive indicator of exocrine pancreatic disease in the dog reflecting the release of PL into the serum as the result of pancreatic acinar cell damage. While originally there was an immunoreactivity test (cPLI), recently a commercial ELISA (SPEC PL) test has been released. This test gives a numerical value of PL in µg/l. Also, a point-of-care commercial SNAP test is available as a colorimetric assay with analytical sensitivity of 200 µg/L for pancreatic-specific lipase. It is considered to have an abnormal result if the assay PL test spot is equal to or more intense than the control test spot.

Several studies have evaluated the sensitivity and specificity of the measurement of PL to diagnose canine pancreatitis. The drawback for all of these studies lies in the inherent problem of what is the gold standard to diagnose pancreatitis. While some have used histopathology, this is not universally available as most dogs with severe acute pancreatitis are considered high-risk surgical candidates where the risks outweigh the benefits.

Table 1. Summary of pancreatic lipase (PL) sensitivity by study

Table 2. Summary of pancreatic lipase (PL) specificity by study

Diagnostic imaging is very useful in animals with suggestive signs of pancreatitis to rule out other problems. Plain radiographs are rarely considered helpful to diagnose pancreatitis. Ultrasonography in the hands of an experienced veterinarian has a sensitivity of 80% and specificity of 88% for feline pancreatitis and probably about the same for canine pancreatitis. Advanced imaging techniques, such as CT, do not appear as useful as they are in humans due to the pancreas being more difficult to visualise. In animals with respiratory symptoms, a thoracic radiograph would also be indicated as thoracic effusions are not uncommon in dogs with pancreatitis.