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Featuring Demian Dressler, DVM and Sue Ettinger, DVM, Dip. ACVIM (Oncology), authors of The Dog Cancer Survival Guide

Carcinoma of the Anal Gland

Updated: October 1st, 2018

One of the less common cancers is carcinoma of the anal gland.

Carcinoma of the anal gland occurs on the rear end of dogs, and are found on the anus, in it, or on the edge where the haired skin starts.  Sometimes they can be found only by doing a rectal exam, which is a good reason every senior (or early senior) dog should have a rectal exam, even females.

There are scent glands within the wall of the anus in dogs and many other animals, which are called anal sacs.  These sacs have anal glands within them which are used for marking territory.  Anal glands are also located in other areas in and around the anus.

These tumors start from an anal gland.

Most commonly, anal sac carcinomas are found in older female dogs who have been spayed.  Sometimes male dogs get the tumor however.

Whenever one of these growths is suspected, a test should be done to see whether the tumor is an anal gland carcinoma, or whether it is a different tumor type.

This type of tumor can sometimes cause elevated blood calcium levels, which will increase your vet’s suspicion of anal sac carcinomas.

However, for real diagnosis, a test of the actual tumor material is needed.  One of the most widely used is a fine needle aspirate.  Sometime though, a biopsy (either before or after removal) is the first step to get a diagnosis, since the tumor may be too sensitive, or in an area that  cannot be reached, using a fine needle aspirate procedure.  Another instance when a biopsy would be used is if the fine needle aspirate was not conclusive.

In this case the growth may be removed or sampled so a piece of tissue is submitted to the lab.

Results of the pathology report usually are returned in 10 days or so.

A plan should be made at this point. Usually the tumor is staged, and an assessment of spread is made.  Using the results of blood and urine testing, X-rays, ultrasound, and sometimes other tools, an idea of how much spread has already happened can be formed.

We should keep in mind though that some of these tumors will spread microscopically (micrometastasis).

The most important treatment step is to have them surgically removed, with as wide margins as possible.  Sometimes they will spread into lymph nodes under the lower spine, or to the lungs.  These tumor should be considered at moderately aggressive overall, and can endanger the lives of dogs with them.

Radiation and chemotherapy are used often along with these steps, depending on how aggressive the tumor is and whether spread has happened or is considered likely in the future.

In the next post, we will look at this dog cancer in more detail.

Best,

Dr D

 

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  1. Denise on September 28, 2020 at 10:48 am

    Hello, My Shih-Tzu has two hard lumps,
    one near each side of his anus. His vet said they may be tumors or cysts but said there was no bloodwork, imaging or aspiration (which I inquired about) that would provide answers. She said the only way to know would be to surgically remove them. She advised against it due his age of 14. I’m thinking I may need to get a second opinion. Do you have any advice? Thank you!

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