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Name
Exocrine Pancreatic Insufficiency
Short Description
Exocrine pancreatic insufficiency
Affected Animals: Both cats and dogs can be affected by EPI,
although it is more common in dogs. Young adult dogs, especially
German shepherds, are most likely to be affected with PAA-associated
exocrine pancreatic insufficiency. Older dogs and cats affected by
EPI will usually develop the disease as a consequence of end-stage
chronic pancreatitis.
Overview: Exocrine pancreatic insufficiency, or EPI, refers
to failure of the pancreas to secrete digestive enzymes normally.
This results in a syndrome characterized by diarrhea and weight
loss, often despite the presence of a normal or increased appetite.
Although EPI can occur in both dogs and cats, the most common cause
is different in each species. EPI in dogs is usually due to a
condition called pancreatic acinar atrophy, or PAA, but in cats it
is most commonly due to end-stage pancreatitis.
Exocrine pancreatic insufficiency is diagnosed on the basis of a
blood test. It is treated with pancreatic enzyme replacements, which
usually result in improvement of the symptoms. However, if EPI is
due to chronic pancreatitis, and is accompanied by diabetes mellitus
or other conditions, it can be more difficult to treat successfully.
Clinical Signs:
Clinical signs associated with exocrine pancreatic insufficiency
include weight loss, polyphagia, coprophagia, pica, diarrhea,
increased borborygmus, and flatulence.
Symptoms:
Animals with exocrine pancreatic insufficiency often show weight
loss despite having a normal or increased appetite. Many dogs with
EPI will have excessive appetites, even for things they normally
would not eat, including their own feces. Diarrhea is often present,
but will vary in consistency and frequency. Grey colored, oily
appearing stools are the classic finding for EPI in young dogs.
Increased rumbling sounds are often heard from the abdomen, and many
affected animals will pass increased amounts of gas. Occasionally, a
long history of intermittent gastrointestinal signs like vomiting,
diarrhea, and reduced appetite will be present if EPI is due to
recurrent bouts of pancreatitis.
Description: The pancreas serves two major functions. One of
these, the endocrine function, is to secrete hormones, particularly
insulin. The second major function of the pancreas is to secrete
digestive enzymes; this is known as its exocrine function. As the
name implies, exocrine pancreatic insufficiency involves
abnormalities in the secretion of digestive enzymes. Since enzymes
are not available to help digest nutrients, the nutrients cannot be
used normally by the body. In addition to the lack of proper
digestion of nutrients, exocrine pancreatic insufficiency is
accompanied by structural and functional changes in the tissue
lining of the small intestine that further impair nutrient
absorption.
The most common causes of exocrine pancreatic insufficiency are
pancreatic acinar atrophy, or PAA, and chronic pancreatitis. PAA is
a disorder that usually affects young adult dogs, particularly
German shepherds. Common symptoms include diarrhea and weight loss
despite a normal or increased appetite. PAA is not known to occur in
cats. Chronic pancreatitis is more commonly a cause of EPI in cats
and older dogs. Animals with EPI due to chronic pancreatitis often
have diabetes mellitus, since the endocrine portion of the pancreas
may also be affected. The symptoms of EPI due to chronic
pancreatitis are the same as those caused by pancreatic acinar
atrophy. However, additional symptoms like intermittent vomiting and
decreased appetite due to pancreatitis, or increased thirst and
urination associated with diabetes mellitus, are present as well.
At the present time, the most important
diagnostic test for EPI is the measurement of trypsin-like
immunoreactivity, or TLI, on a blood sample drawn after a 12-hour
fast. Once the diagnosis is confirmed, the main treatment is the
oral administration of enzyme replacements, which are usually taken
with each meal. Additional treatments, discussed in the treatment
section, may be appropriate.
Diagnosis:
The key diagnostic test for exocrine pancreatic insufficiency is
called the serum trypsin-like immunoreactivity test, or TLI. The
affected animal's blood sample for this test should be drawn after
at least a twelve-hour fast. A low value on this test, accompanied
by symptoms consistent with EPI, virtually confirms the diagnosis.
Routine bloodwork and other laboratory tests may help establish the
diagnosis of concurrent diseases, but are generally not helpful in
diagnosing exocrine pancreatic insufficiency per se. Mild liver
enzyme changes, and low serum cholesterol levels may be seen with
EPI, but other significant test findings indicate clinical processes
other than, or in addition to, EPI.
Prognosis: Treatment of exocrine pancreatic insufficiency is
usually necessary for life. Most dogs with EPI due to pancreatic
acinar atrophy respond well to enzyme replacement alone, and have a
good long-term prognosis. Although affected dogs do not always
regain the weight they lost, most of them develop normal stools and
no longer continue to lose weight. Animals requiring additional
medications to boost the effectiveness of enzyme therapy generally
do well.
In cats and in older dogs with EPI due to chronic pancreatitis, the
outcome is much less predictable. If other conditions are present,
particularly diabetes mellitus, then the prognosis may depend more
on the ability to treat these complicating factors successfully.
Less is known about the prognosis of cats with EPI because it occurs
much less frequently in felines.
Transmission or Cause: Pancreatic acinar atrophy, or PAA, is the most
common cause of exocrine pancreatic insufficiency in dogs. This is
common in young adult dogs, but it is not recognized in cats. The
underlying cause for PAA is unknown. Nutritional imbalances,
pancreatic duct obstruction, toxins, interruption of blood flow to
the pancreas, viral infection, immune system abnormalities, and
defects in pancreatic development or enzyme secretion have all been
suggested as possible causes. PAA can occur in dogs of all breeds
and ages; however, due to its relatively higher incidence in young
German shepherds, there may be a hereditary contribution to its
development in dogs of this breed.
End-stage inflammation of the pancreas, or pancreatitis, may also
result in EPI. When this is the case, diabetes mellitus may also be
seen due to damage to the endocrine portion of the pancreas.
Pancreatitis is more commonly the cause of EPI in cats and older
dogs.
Treatment: The main treatment for exocrine pancreatic insufficiency
is the administration of enzyme replacements that are given with
each meal. If the diagnosis of EPI is correct, and if sufficient
enzyme supplement is provided, diarrhea will begin to resolve in a
few days, followed by gradual weight gain in most dogs. It is very
important to establish the diagnosis of EPI before starting
pancreatic enzyme replacement therapy. Enzyme replacement can be
expensive, and usually must be given for the rest of the patient's
life. Some animals with diarrhea and a provisional diagnosis of EPI
are treated with pancreatic enzyme replacements even when the
diagnosis of EPI has not been confirmed. These animals may have
resolution of their diarrhea for reasons other than enzyme
replacement. If their response to treatment is incorrectly
interpreted as confirming the existence of pancreatic insufficiency,
they may be kept on an expensive and potentially unnecessary
treatment for a long time.
Once an appropriate dose is found that controls the symptoms, the
enzyme dose can be reduced until the lowest dose that maintains
control is identified. The powder form of enzymes is generally more
effective than tablets, although the latter are easier to
administer.
Some animals do not respond appropriately to enzyme replacement
alone. These patients may benefit from medications that augment
enzyme replacement therapy. Certain drugs that block H-2 receptors
in the stomach may increase enzyme replacement effectiveness by
preventing breakdown of the enzymes in the stomach.
Some dogs seem to do better when they are fed a low fat, low fiber,
highly digestible diet, but most dogs do not need specific dietary
treatment for EPI. Oral vitamin E supplementation or intramuscular
injections of vitamin B-12 may be administered to restore serum
concentrations of these substances in dogs with EPI. Although such
deficiencies have been documented in EPI, it is not known if they
are significant. Rarely, dogs with these vitamin deficiencies that
do not respond to enzyme replacement alone will do better when these
deficiencies are corrected. Antibiotics may be helpful in some dogs
if excessive bacterial growth in the intestines has occurred.
Although cats are treated less often for EPI, similar dietary and
vitamin supplementation may be appropriately attempted in certain
cats.
Prevention: There is no known means of prevention of exocrine
pancreatic insufficiency. Affected German shepherd dogs should not
be bred since EPI may be inherited in that breed.
