Perianal Adenoma and Perianal Adenocarcinoma


Perianal adenocarcinoma treatment - non- surgical

Question: Our 8 year old Siberian Husky was diagnosed with perianal adenocarcinoma back in September. Ultrasound confirmed mets to the abdominal lymph nodes. We followed up with an oncologist for a second opinion and after discussing the risks and benefits of surgery we decided against it.

She has been doing fairly well externally. She is eating and eliminating waste well. She does not appear unhappy or uncomfortable. She is on 2 Colace stool softeners once a day and we have been giving her Prednisone to help control the calcium levels. We started her on 20mg 2x/day. Her calcium rose to 13 (11 is high limit) and we increased the Pred to 30mg 2x/day. This seemed to have lowered it back to around 11. But its hard to confirm that it was the Pred and not just a natural fluctuation. Her most recent bloodwork showed the calcium to be at 14.8. We are going to try to increase the Pred to 40mg 2x/day. But I get the impression from the Vet that it probably wont make much of a difference.

Do you know of any alternatives we can try instead of or in combination with the Prednisone? We are willing to try herbal/alternative medicines as well. We definitely don't want to put Chinook into kidney failure and would like to give a good attempt at getting this calcium under control. Also, at what levels do the kidneys start to have significant problems? In general, how long does it take (ballpark)? What signs would we look for and how quickly does it progress?

Thank you so much for your help. I know you cant give any definite answers because cases and animals vary. I'm just trying to get a few opinions so that we can be at peace with our decisions.

Thank you, Jody

Answer: Jody-

The most commonly used treatments for increased calcium are corticosteroids, furosemide (a diuretic) and administration of fluids containing sodium chloride. In some cases, administration of sodium bicarbonate may help a little, as well. There are other medications, such as calcitonin administration, mithramycin and peritoneal dialysis are possible, but have significant side effects in some patients and should probably be withheld until other options have been exhausted.

It is necessary to use the higher end of the dosing spectrum for furosemide. It is often used at 1 to 2mg/kg for other purposes but works better in the 2 to 4mg/kg range for reducing calcium in the blood stream. At this dose it is important to make sure that the patient stays hydrated or there can be kidney problems. Most dogs will drink enough water to stay hydrated but it must be available at all times. When patients are getting sodium chloride fluids intravenously at the same time furosemide is being used dehydration is less of a problem.

Hypercalcemia starts to be worrisome at about 15mg/dl and becomes threatening to the kidneys, heart and nervous system at about 18mg/dl. It is often possible to keep the levels below this point with treatment, even without being able to treat the underlying malignancy.

Good luck with this.

Mike Richards, DVM 1/15/2001

Perianal Adenoma

Q: My 8-year-old female Cocker Spaniel was recently diagnosed as having a perianal adenoma. Her doctor suggests surgical removal. What causes this condition? Is the condition likely to reoccur? What are the chances that this would be a malignant tumor?

A: Perianal adenomas are usually a benign tumor that affects older, intact, male dogs. In male dogs these occur in tissues around the rectum that are responsive to androgens (like testosterone) and develop into benign tumors under the effect of these hormones. Unfortunately, when these tumors occur in spayed female dogs they are much more likely to be malignant than not. A malignant version of this tumor is known as a perianal adenocarcinoma. There is no way I know of to tell them apart based on appearance visually. The tumor should be removed and sent to a pathologist for histopathologic examination. Careful examination of the surrounding tissues might reveal metastasis of the tumor. If your female dog is unspayed, there is a greater chance that the tumor would be benign but it would still be more likely to be malignant than in a male dog.

There are a number of skin growths that can resemble perianal adenomas and perianal adenocarcinomas. Even though the above information is scary, please don't get too concerned until you have the pathologist's opinion. After many mistaken guesses about what type of tumor is present on an exam, I am less and less willing to make a guess prior to biopsy.

Mike Richards, DVM

Growth at anal area - Perianal Adenoma

Q: Dear Dr Mike; I have an 11 year old male Chow Chow that has not been neutered. Yesterday, I noticed an apparent growth near the anus. It is approximately 1/2 inch long and about 1/4 in diameter. I immediately took the dog to our local Vet, and was told that it is a common problem in older intact males. The Vet indicated there is a 15% probability of it being malignant. Their recommendation is to have the grow surgically removed AND that the dog be neutered. I seem to recall that several years ago, a similar growth was detected, and the Vet merely aspirated the growth and it disappeared. This particular vet indicated that this would be something we should keep an eye on, but that it was common and not to be overly concerned. Unfortunately, the Vet I visited several years ago has since retired out of the country and cannot be contacted. I would appreciate any comment you could make! Thank you, Curtis

A: Curtis- If your new vet thinks that the growth is a perianal adenoma, which would be the most likely tumor around the anal area then his or her advice is correct. These are generally benign but growth is stimulated by testosterone and castration will reduce the risk of recurrence and the risk of a malignancy developing. If you are concerned that the diagnosis is not correct you can always opt for a biopsy first and castration if the results come back perianal adenoma -- but that would mean that there would be two surgeries and two anesthetic procedures which is less than ideal, unless the tumor can be biopsied with a local anesthetic.

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...