Exocrine Pancreatic Insufficiency
A Syndrome caused by insufficient secretion of pancreatic digestive enzymes by th exocrine pancreas cause EPI
SPECIES, AGE, SEX
Occurs more commonly in dog than in cat. In dog of breeds that are affected by pancreatic acinar atrophy ( PAA ), exocrine pancreatic insufficiency ( EPI ) is most commonly diagnosed in young adults. In other dog breeds and cats, EPI can occur at any age.
GENETICS AND BREED PREDISPOSITION
In some dog breeds ( i.e., German Shepherds, rough-coated collies, and Eurasians ) EPI is considered to be hereditary; a simple autosomal recessive inheritance, until recently suspected to be the mode of inheritance in the German Shepherd dog, has now been confirmed. There is no known breed predilection in cat. See Etiology, below, regarding PAA.
Many canine and feline patients with EPI have other gastrointestinal disorders. Dogs with EPI due to PAA commonly have secondary small0intestinal dysbiosis (formerly known as small-intestinal bacterial overgrowth or antibiotic-responsive diarrhea). Other dogs and cats can have concurrent inflammatory bowel disease.
HISTORY, CHIEF COMPLAINT
- Weight loss is the most common clinical sign in both dogs and cats.
- Loose stools and less commonly diarrhea
- Ravenous appetite
- Unlike dogs, approximately 40% of cats can have decreased appetite.
PHYSICAL EXAM FINDINGS
- Poor body condition (Note: nowadays patient often are diagnosed mush earlier in the disease process, and emaciated patients with EPI are rare.)
- Poor haircoat and sometime in cats, greasy soiling of the haircoat, especially in the perianal area.
Etiology and Pathophysiology
- Approximately 50% of dogs with EPI have PAA, à condition that is mostly seen in German Shepherds, rough-coated collies and Eurasians.
- In the vast majority of the remainder of dogs and in almost all cat, EPI is due to chronic pancreatitis.
- Other potential rare causes of EPI include obstruction of the pancreatic duct by a pancreatic adenocarcinoma or abdominal surgery, pancreatic aplasia, or pancreatic hypoplasia.
- Decreased secretion of exocrine pancreatic digestive enzymes leads to lack of digestive enzymes in the small intestine, which will lead to maldigestion and associated clinical signs.
- Secondary cobalamin deficiency is very common in dog and occurs in almost all cat with EPI.
- In patients with EPI du to chronic pancreatitis, pancreatic inflammation may also lead to destruction of islets of Langerhans and cause concurrent diabetes mellitus.
The most reliable diagnostic test for both dogs and cats is serum trypsin-like immunoreactivity concentration (TLI), which is measured by specific assays.
- Primary small-intestinal disease (e.g., inflammatory or infiltrative bowel disease)
- Other secondary causes of chronic diarrhea and weight loss (i.e., hepatic failure, chronic kidney disease, hypoadrenocorticism hypothyroidism <dogs>, hyperthyroidism <cats>, or other less common cause)
- CBC, serum chemistry profile, and urinalysis are usually within normal limits.
- Imaging studies are usually within normal limits.
Advanced or Confirmatory Testing
- Serum TLI is the diagnostic test of choice for a diagnosis of EPI in dogs and cats.
A severely decreased serum TLI concentration is diagnostic of EPI.
- In dogs: < 2.5 mcg/L (cTLI; reference range 5.7 – 45.2 mcg/L (fTLI; reference rance 12 -82 mcg/L)
- In cats: < 8.0 mcg/L (fTLI reference range 12 – 82 mcg/L)
Some patients with EPI may have a serum TLI concentration in the questionable range (>2.5 but <5.7 mcg/L for dogs; >8.0 but <12.0 mcg/L for cats)
- These patients most likely have chronic small-intestinal disease and should be evaluated accordingly and retested 4 – 6 weeks later.
- Other diagnostic tests are much less reliable and should not be used for the diagnosis of EPI:
- Fecal proteolytic activity is only recommended in species for which a TLI assay is not available (e.g., ferrets).Measurement of fecal elastase concentration is only available for dogs and only in Europe. However, a positive test result is not specific for EPI and most be confirmed with a cTLI test as the false-positive rate is high.
- Serum cobalamin concentration should be part of the database in dogs and cats diagnosed with EPI since 80% of dogs and virtually all cats will be cobalamin deficient and therefore require parenteral supplementation.