Insulinomas - tumors of the pancreas


Insulinomas - tumors of the pancreas

Question: DR. RICHARDS, I have a six year old shep/husky that we believe has a tumor on his pancreas, his last blood work showed his insulin level @ 1400 and his sugar level @31.His sugar level is so low he is extremely weak. I can not find anyone who has any information on the chances of removing the tumor,and the risks involved. It is very diffucult to make a decision about exploratory surgery with very little information .I understand that you can't diagnois via internet, but would appreciate greatly any input you could give me. I really need to gather facts as soon as possible. THANK YOU

Answer: Joseph-

Insulinomas, the tumor of the pancreas that leads to low blood sugar and high insulin production, will commonly metastasize (some people say this tumor always metastasizes) and recurrences of the tumor after removal do occur in most patients. It is a good idea to have chest X-rays taken prior to making a surgical decision, since it would be much less likely to help if there are already visible tumors in the chest. If there is a good ultrasonagrapher in your area, an ultrasound exam can help to determine the size of an insulinoma prior to surgery and help to determine if there is a metastasis to the liver.

Surgery increases the lifespan of affected dogs because it helps to reduce the amount of excessive insulin being produced by the tumors. This effect is usually temporary because the tumor has usually spread. It isn't possible to find all the tumors once this has happened and eventually there will be a recurrence of the hypoglycemia. As an average, according to information on the Veterinary Information Network, the interval before return of clinical signs is about 8 months if there are already visible metastases prior to surgery and about 14 months if there are no metastases visible at the time of surgery. With a combination of medical and surgical therapy, life spans of about 2 years have been recorded for patients after diagnosis of insulinoma.

It is risky to do surgery on patients who have low blood sugar. It is probably best to have an experienced surgeon for this procedure. We have removed insulinomas in our practice and the surgery itself is not all that difficult but fluids with dextrose should be administered during surgery and blood glucose monitored during surgery, as well. I am still more comfortable referring these patients to a facility with twenty-four hour care and board certified surgeons when possible.

After surgery, when hypoglycemia returns as a problem, medical therapy works for a while to control clinical signs. Medical therapy includes feeding many small meals, administration of prednisone and use of diazoxide. There may be some addition information available to your vet by calling a veterinary school, as there has been a small amount of work done on specific chemotherapy agents for this condition and the use calcium channel blockers (usually used to control blood pressure) as an aid in controlling blood sugar since they sometimes lower it as a side effect to their normal actions.

It is possible to use medical therapy without doing surgery but surgical removal of as much of the mass as possible helps more than anything else in extending lifespan of patients with insulinomas. This is a temporary effect, so you have to think about how important it is to you and your dog to gain a year or so of time. There are a few dogs who actually seem to recover completely post surgically but the percentage is probably less than 5% and may be even lower than that.

Hope this helps some.

Mike Richards, DVM 6/5/2000


Q: DEAR DR. MIKE; MY DOG , SUKI , GOLDEN RETRIEVER LAB MIX , EIGHT YEARS OLD: - STARTED HAVING SEIZURES BACK IN NOVEMBER. - AFTER MANY TESTS MY VET DIAGNOSED HER WITH INSULINOMA. - SHE HAD AN OPERATION AND THEY REMOVED TUMORS FROM HER PANCREAS, LYMPH NODE, LIVER. - They had to leave a tumor that was too dangerous to remove near an artery. - She is on hormonal injection 2x's / day AM & PM = "Sandostatin." - The vet has us feeding her 4 small meals per day which has seemed to help the seizure problem (only problem she still loves to steal food! -that's good!) - She injured her shoulder (a few month's after the operation - she started feeling better and wanted to run & play).

The VET prescribed prednisone @ 1/2 tab (whole tab = 20mg.) 1x every other day and this seems to have helped the limping from the shoulder injury. - She seems to have suffered some nerve damage on the right side of her face (she had been on the prednisone for c. 2 mos. at this point): drooping = right ear, right side of mouth = constant drooling, right eye not able to blink & I think there is some loss of sight in that right eye. - HISTORY OF IMPORTANCE: was always very active & got plenty of exercise but has now slowed down some, she had LYME DISEASE c. 8 yrs. ago, has arthritis in her back.


Answer: I don't think that the prednisone is a likely suspect as a cause of the facial paralysis. This happens spontaneously in some golden retrievers and it is also associated with hypothyroidism and brain tumors. Since your dog has a metastatic cancer, pressure on the facial nerve from a tumor has to be considered.

Octreotide (Sandostatin Rx) is a relatively new treatment for insulinoma and the initial reports on it were promising. A journal article by Simpson et. al in the Journal of Small Animal Practice suggests that it is not an effective treatment, though. I have no personal experience to draw from and can not help with deciding who is right (the vets who think it works or the ones who think it doesn't).

An alternative medication is diazoxide (Proglycem Rx). It is expensive and sometimes hard to find but it has been the standard treatment for the hypoglycemia associated with insulinomas for some time. It is almost always used in conjuction with prednisone so it is unlikely you could discontinue the pred with its use.

There is an alternative veterinary medicine question and answer board on AOL (keyword pets, then use the veterinary hospital button) if you wish to seek alternative treatment advice.

Mike Richards, DVM


Michael Richards, D.V.M. co-owns a small animal general veterinary practice in rural tidewater Virginia. Dr. Richards graduated from Iowa State University's College of Veterinary Medicine in 1979, and has been in private practice ever since. Dr. Richards has been the director of the PetCare Forum...