Body

VetInfo Digest

September 2005

Table of Contents:

Pancreatitis

New Stuff

This Month's Note:

It is likely that some of you have noticed on the web site that we are no longer accepting new subscriptions to the newsletter or subscriber area. We have decided to take this step in order to allow time to revise the information on the web site. This decision does not affect our current subscribers who wish to continue to receive the VetInfo Digest and to have access to the subscriber area. We will continue to accept renewals on subscriptions and to answer subscriber questions until the time comes when no one wants to continue to their subscription.

As we update the web site I hope to add links in the subscriber area to the revised pages of the web site as they are updated. I am hoping to have site revisions completed within 2 years. At that time we will decide whether to accept new subscriptions again. We intend to accept more advertising than we have in the past to cover some of the income loss that will occur during this time. We are hoping to be able to do this without compromising the site's message in any way. Hopefully we're not being too naive in that goal.

The only link to subscribe will now be in the subscriber area, so please let us know if you have problems accessing this portion of the web site.

Pancreatitis, General Information

Pancreatitis is inflammation of the pancreas caused by leakage of active digestive enzymes into the pancreatic tissue. This causes various clinical signs but most pets affected by acute pancreatitis have abdominal pain, depression and decreased appetite or lack of appetite. Vomiting and diarrhea occur in many dogs with pancreatitis. In severe cases of pancreatitis there may be signs of shock or total collapse. Chronic pancreatitis in dogs may occur, with similar but less severe symptoms. The signs of acute pancreatitis similar to those seen in dogs are not as common in cats and probably account for less than 25% of the cases of pancreatitis among felines. Cats are more likely to have chronic pancreatitis, characterized by a decrease in appetite, lethargy, loss of weight, chronic vomiting and low body temperatures. Cats sometimes have diarrhea or difficulty breathing.

The pancreas has several jobs that it performs for the body. The pancreas produces digestive enzymes that break down food into molecules that can be absorbed from the intestine. Special clusters of cells in the pancreas, the islets of Langerhans, produce insulin. Diabetes occurs when these cells do not function properly or when they no longer function at all.

It is unusual for acute pancreatitis to cause acute diabetes mellitus and unusual for chronic pancreatitis to lead to diabetes mellitus, but there are cases in which these things happen. These complications are much more common in dogs than in cats. It is particularly important to be aware of the possibility of diabetes occurring with severe acute pancreatitis and just as important to remember that this is usually a temporary situation. It is critical to monitor insulin needs very closely if an attempt is made to correct high blood sugar using insulin in a dog with acute pancreatitis, in order to avoid the risk of shock due to an over dosage of insulin when the islet cell function returns and the pancreas begins to make insulin normally.

Digestive enzymes produced by the pancreas are capable of digesting the dog or cat's body just as well as they digest food. For this reason there have to be very good self-protective mechanisms in the body to keep the digestive enzymes from leaking and to deactivate them when they are leaked. Both of these mechanisms have to work well in order to prevent pancreatitis. There are a large number of things that can interfere with the protective mechanisms of the pancreas.

Pancreatitis is more common in overweight pets. When pancreatitis occurs in an overweight pet it is more likely to cause serious illness, as well. This is one of the many good reasons to keep your pet at or close to its ideal weight.

High fat diets, especially in combination with low protein intake, appear to contribute to the development of pancreatitis. A single high fat meal may cause pancreatitis in a pet whose normal diet is moderate or low in fat. We see an increase in cases of pancreatitis around Thanksgiving, Christmas and Easter almost every year, presumably due to the ingestion of high fat leftovers from the big meals associated with these holidays.

There are a number of drugs that have been linked to pancreatitis. The most well known of these, prednisone (or other corticosteroids) apparently doesn't actually lead to pancreatitis, at least according to recent information in humans (J.M. Steiner, 2005). The medications most suspected of causing pancreatitis include azathioprine (Imuran Rx), potassium bromide (used for seizure control), l-asparaginase ( a chemotherapeutic agent) and zinc used as a dietary supplement. There are a number of other medications that are sometimes mentioned as possible causes of pancreatitis but the relationship with it is less clear for most of those medications. Pets living in areas in which scorpions occur may develop pancreatitis after scorpion stings. Naturally occurring hypercalcemia ( too much calcium in the blood stream) can lead to pancreatitis and it is likely that over supplementation with calcium or calcitriol could also lead to pancreatitis.

It is unclear whether there is a genetic predisposition to pancreatitis in dogs and cats. Pancreatitis is much more common in miniature Schnauzers than in most other breeds but this could be due to a genetic predisposition to hyperlipidemia (high fat content in the blood stream) rather than a direct genetic link to pancreatitis.

Pancreatitis in cats tends to occur in combination with other disorders, especially inflammatory bowel disease (IBD) and cholangiohepatitis (liver disease). All three of these problems occur at the same time in a fair number of cats and the combination is currently being called "triad syndrome". At the present time it is unclear whether any of these conditions can lead to the other ones or whether they just happen to occur together frequently. It seems likely that IBD may be able to cause chronic pancreatitis but for now this is unproven. All three of these disorders are seen most commonly in older cats and this syndrome is a major cause of chronic weight loss and chronic vomiting in older cats.

Toxoplasmosis, a parasitic infection, can cause pancreatitis in cats. This should be suspected when pancreatitis occurs in young cats, or in groups of cats or when there are other signs of parasite infection such as neurologic disease, visual problems, weight loss or unexplained diarrhea. Another parasitic cause of pancreatitis in cats is a liver fluke, Amphimerus pseudofelineus, which has been diagnosed sporadically in a number of states in the U.S.

The most severe form of pancreatitis is referred to as necrotizing pancreatitis, which basically means pancreatitis in which the damage is so severe that portions of the pancreas are being killed. Some authors refer to this as hemorrhagic pancreatitis. This form of pancreatitis can be fatal and requires early intervention and aggressive treatment when it is present. Dogs with necrotizing pancreatitis usually look severely ill and are usually in obvious pain or extreme discomfort. Cats are extremely depressed and won't eat but may not show much else even though the pancreatitis is very severe.

* * * *

Diagnosis of Pancreatitis in Dogs

Pancreatitis in dogs causes a number of changes in routine blood counts and blood chemistries. Taken in concert these changes can be highly suggestive of pancreatitis but do not definitely confirm its presence and can not be used to completely rule it out. Mild to moderate increases in white blood cell counts generally occur with pancreatitis. Serum amylase and lipase enzyme levels are often three times normal in dogs with pancreatitis, although these enzyme levels can rise for other reasons and do not uniformly rise in dogs with pancreatitis. Rises in liver associated enzymes, particularly alkaline phosphatase and alanine transferase (ALT) may occur in conjunction with pancreatitis. Mild rises in blood sugar and mild to moderate decreases in serum calcium levels sometimes occur. Some dogs will have moderate to severe rises in blood potassium levels. When several of these changes occur at the same time pancreatitis is very likely.

The most accurate blood test for canine pancreatitis at the present time is the canine pancreatic lipase immunoreactivity (cPLI) test. This is a specialized blood test that is only run at the current time at the Gastroenterology Laboratory at Texas A&M University. Some commercial labs offer this test but they just provide a convenient way for veterinarians to get the blood to Texas A&M.

Radiographs (X-rays) are not highly specific for detection of pancreatitis. There are some subtle changes that can occur when pancreatitis is present but X-rays are at best a supportive test for making the diagnosis of pancreatitis. Ultrasound examination, when performed by a good ultrasonagrapher, is a good way to diagnose pancreatitis but even the best ultrasonagraphers can only detect pancreatitis about 70% of the time and false positive findings may be common with less experienced sonagraphers.

Pancreatic biopsy is considered to be the definitive or "gold standard" test for pancreatitis. In general most vets want to avoid exploratory surgery to obtain pancreatic tissue for biopsy but if surgery is necessary pancreatic biopsy is possible.

* * * * * *

Diagnosis of Pancreatitis in Cats

Perhaps the greatest roadblock to diagnosis of pancreatitis in cats is simply recognizing that it might be present. Cats are much better at hiding the pain and other symptoms of pancreatitis than dogs and it is very likely that the number of cats who have pancreatitis far exceeds the number of cats who are expected of having it --- meaning that very often no one looks for the disease even though it is present. The other great roadblock in diagnosing pancreatitis in cats has been the lack of a single really good test for this disease.

Radiographs and ultrasound examination are both less useful in cats than in dogs for diagnosing pancreatitis. Even very good ultrasonagraphers have difficulty identifying pancreatitis in cats, although the diagnosis is likely to be correct if standard guidelines for diagnostic criteria are followed and it can be made. X-rays really provide very little information about the possibility of pancreatitis in cats.

Routine blood counts and blood chemistry analysis in cats is also less helpful than in dogs. Amylase and lipase values in cats do not seem to correlate well with pancreatitis. Serum chemistry values tend to be normal in cats with pancreatitis. If the liver associated enzymes (alkaline phosphatase, ALT) are high in an older cat it is reasonable to suspect that pancreatitis might be present just because liver disease and pancreatitis occur at the same time fairly commonly in cats. Trypsin-like immunoreactivity (fTLI) testing could detect pancreatitis with good reliability but was not a very sensitive test for the condition. Cats with severe pancreatitis may have low serum calcium levels. This can be a significant finding from a prognostic standpoint, as very low calcium levels are associated with a poor prognosis in cats.

Recently the Texas A&M Gastroenterology Laboratory has been able to develop a feline pancreatic lipase immunoreactivity test for cats (fPLI) and this test is more sensitive and as specific as the trypsin-like immunoreactivity test. This test is currently the best available test for pancreatitis in cats.

Biopsy of the pancreas can also be used to determine if pancreatitis is present and is a useful test when it is possible to obtain pancreas tissue samples. This is sometimes done when obtaining liver biopsy or intestinal biopsy samples from cats who are exhibiting signs of more than one disease, especially the "triad syndrome" cats who have all three problems at the same time.

One point important to note about laboratory testing for pancreatitis in cats is that amylase and lipase levels rise in many cats with chronic renal failure and in some cats rises in these enzymes are the first sign that the kidney function is not sufficient for all daily needs. Many cats with rises in these enzymes as an early indicator of renal disease have no other clinical signs and the amylase or lipase rise is found in routine lab work done for presurgical purposes or for other routine reasons. It is easy for a veterinarian who is used to seeing pancreatitis in dogs to assume that the increase in amylase or lipase in a cat may indicate pancreatitis, especially if he or she is unaware of the potential for rises in these enzymes due to kidney failure.

* * * * *

Treatment of Pancreatitis in Dogs

For dogs there are two cornerstones to treatment for pancreatitis, control pain and control fluid and electrolyte disturbances. If these two things can be accomplished the prognosis for living through the pancreatitis improves a great deal.

There are a number of pain control medications which can be used in dogs with pancreatitis. The most commonly used pain relievers are probably meperidine (Demerol Rx), fentanyl patches (Duragesic Rx) and morphine but there are several other medications that can be used. The most important thing is to use some kind of pain relief medication. For severely ill dogs the use of continuous IV pain relievers or injection of local anesthetic (lidocaine) into the abdominal cavity along with sufficient fluids to make sure that it spreads everywhere can be very beneficial. This type of therapy is most common at critical care centers and veterinary schools and there is some advantage to asking for referral to a critical care center when a dog has severe pancreatitis.

Most dogs with pancreatitis benefit from fluid therapy designed to keep their electrolytes within normal ranges. Low potassium levels are a common problem in dogs with pancreatitis but high potassium levels can also occur and are more dangerous for the dog. Keeping a dog well hydrated makes him or her more comfortable and aids in the recovery from pancreatitis, as well. Severely ill dogs may also benefit from administration of plasma to ward off the disseminated intravascular coagulation (DIC), a severe form of shock that sometimes occurs with necrotizing pancreatitis. It is necessary to monitor electrolytes and acid/base balance to choose the best possible replacement fluids so dogs who have pancreatitis may need repeated blood work over the first few days of treatment.

Dogs do not usually require antibiotic therapy when they have pancreatitis but there are exceptions to this rule. If the white blood cell count gets very low or very high, body temperature very high or if other signs that a secondary infection may be present occur it is acceptable to use antibiotics. If vomiting is severe the use of medications to control vomiting may be necessary. In general it is probably better to wait to see if vomiting self corrects, as this is a good prognostic sign and also is an indication that it is acceptable to give fluids and food orally.

For almost my entire career in veterinary medicine the standard feeding advice for dogs with pancreatitis was simply to avoid feeding them while there were clinical signs of acute pancreatitis present, even if they didn't eat for a week or more. This philosophy is changing, mostly due to the results of some studies in humans that show an improvement in survival rates and recovery times among patients who are fed early in the recovery from pancreatitis. At the present time it is reasonable to give oral fluids and to feed dogs once the vomiting stops. Small amounts of a low fat food are best. For dogs who will not eat on their own there is evidence that implanting a feeding tube directly into the small intestine (jejunostomy) seems to be beneficial but is usually something that is done more commonly at critical care centers than general veterinary practices.

There may be some benefit to supplementing pancreatic enzymes orally using products such as Viokase (tm). This has not been proven in dogs but human studies show some benefit in pain relief from supplementing enzymes. This is probably due to a feedback mechanism in which the presence of digestive enzymes in the intestines shuts down the release of digestive enzymes from the pancreas, limiting the damage to the pancreas.

Some dogs who have chronic pancreatitis will have fairly frequent attacks of mild abdominal pain. It is often possible to wait these symptoms out and not to provide treatment, as long as the dog doesn't seem to be in too much pain or to be too ill. I prefer to go ahead and dispense pain relief medications for these dogs and to start them early but there is no way to know if this is the ideal practice at this time.

* * * * *

Treating Cats with Pancreatitis

It is much harder to figure out how to treat cat with pancreatitis than dogs. If the cat has classic signs of pancreatitis such as vomiting and abdominal pain it can pretty much be treated in the same way as dogs are, pain relief and fluid therapy. Most cats with pancreatitis have much more subtle signs and it is much harder to decide the optimum therapy for them.

I suspect that many more cats have pain from pancreatitis than show this pain. I think it is best to just assume that pain is present and to attempt to use pain control if pancreatitis is suspected, especially acute pancreatitis. Unfortunately, the choice of appropriate pain relievers is smaller for cats than for dogs. It is possible to use fentanyl patches (Duragesic Rx), tramadol (if oral medications can be used), buprenorphine, constant rate intravenous infusion of ketamine or morphine (must be done carefully in cats) or butorphanol (Torbutrol, Torbugesic SA Rx).

Cats also benefit from fluid therapy but do not seem to have quite as much problem with electrolyte disturbances as dogs do. Despite this, it is a good idea to monitor electrolytes as low potassium and low calcium levels can be serious concerns in cats with pancreatitis.

In dogs there does not seem to be much use for corticosteroids but in cats they may be essential to control pancreatitis induced by inflammatory bowel disease or cholangiohepatitis. If this is the case there are usually no problems with using corticosteroids even though pancreatitis is present. Some veterinarians believe that pancreatitis is an immune mediated disease in cats and that there may be direct benefits to the pancreas from the use of corticosteroids but this is uncertain.

Cats get into trouble when they don't eat much faster than dogs. Any cat who appears to have pancreatitis and who has not been willing to eat for more than 48 to 72 hours should probably have a feeding tube placed and should be fed through the tube. For temporary feeding a nasogastric tube is sufficient but for longer term feeding it is necessary to consider an esophageal, gastric or jejunal feeding tube, all of which require surgical implantation of the tube. This is another situation in which it can be very helpful to consider asking for referral to a critical care facility as they are much more likely to place a feeding tube and to maintain the tube until it is clear that the risk of secondary hepatic lipidosis (a form of liver disease) is over. This point is reached when the cat will readily take foods in orally on its own.

It is critically important to remember that pancreatitis in cats must be recognized to be treated. Whenever a cat has inflammatory bowel disease or increases in liver enzymes it is necessary to consider the possibility that pancreatitis may be present. This is especially true when treatment for liver disease or IBD is not going as well as is expected.

* * * * * *

Preventing future occurrences of pancreatitis

In dogs there is a general consensus that a low fat, moderate fiber diet is helpful in preventing future occurrences of pancreatitis. In addition to diet, weight control is a very important factor in controlling the incidence and severity of future attacks of pancreatitis. Overweight dogs seem to have more severe bouts of pancreatitis when it occurs and to have recurrences more frequently. Dog breeds, or individual dogs, prone to hyperlipidemia, especially miniature schnauzers, may also benefit from the use of statin medications, such as Lipitor (Rx) to control the lipid levels in their bloodstream. This has not been proven at this time but reports from vets trying these medications on an experimental basis seem positive -- just remember that anecdotal evidence is always suspect and that this is an experimental therapy.

Cats seem to benefit from control of any contributing or concurrent illnesses, such as inflammatory bowel disease or cholangiohepatitis. It is unclear whether or not there is any benefit to dietary changes in cats, other than those that may benefit concurrent illnesses. In another instance of having to rely on unproven medical therapies, there does seem to be benefit for some cats from the use of low doses of prednisone to prevent future occurrences of pancreatitis. There is a very good chance that the major benefit may be due to effects on the intestinal tract and liver and it may be more important to consider this therapy in cats with IBD or cholangiohepatitis than for pancreatitis that seems uncomplicated. It is very likely that weight control has a place in preventing future attacks of pancreatitis in cats but this is also not well documented at this time. Cats with either inflammatory bowel disease or pancreatitis can be deficient in Vitamin B12 (cobalamin). Supplementing this vitamin through periodic injections may be very beneficial for some cats. Oral administration of cobalamin doesn't seem to work as well. This information is relatively new in veterinary medicine but can be found in the new edition of the "Textbok of Veterinary Internal Medicine" if your vet needs a reference for the rationale and dosing requirements.

New Stuff

For those of you with cats or dogs suffering from chronic kidney disease, which seems to be the current accepted term for kidney insufficiency or chronic kidney failure, there is a new phosphate binder on the market. If you have tried Amphogel (tm) or similar products in the past you might appreciate Epakitin (tm), a chitosan supplement that is supposed to taste good and to be easy to administer. There aren't many supportive studies in veterinary medicine at the present time but human studies support the use of chitosan as a phosphate binder.

Thanks for your Support!

The VetInfo Digest is published by:

TierCom, Inc.

P.O. Box 476

Cobbs Creek, VA 23035.

The opinions expressed in this newsletter are those of Michael Richards, DVM., author.