Anal Gland Cancer in Dogs

The anal glands are small sacs found on either side of the anal opening of your dog. The lining of the sacs produces a small amount of liquid, which is eliminated each time your dog defecates. The development of a tumor in this area can be significant; even with the presence of a small growth there is the definite possibility that the tissues will be invaded and the cancer will spread (metastasize). In some cases, the tumor can cause hypercalcemia (elevated blood calcium), leading to kidney failure.

An anal gland tumor is not always obvious to the eye as the tumor may be growing inward. If your dog has an anal gland tumor, he may present some or all of these symptoms:

• Scooting his hind end along the ground
• Licking of the perianal area
• A lump beside the anus
• Straining and displaying difficulty passing feces
• Blood in the stool

Apocrine Gland Adenocarcinoma may lead to kidney failure due to elevated blood calcium which may present as follows:

• The increased need to drink
• Frequent urination
• Vomiting
• Muscle weakness

As we find in humans, the cause of cancer is not always easily discovered. We do know that cancer found in the anal gland is diagnosed equally in male and female dogs. This type of cancer is most often found in dogs of medium to middle age. Reports have shown that spaniel breeds are found to be at increased risk for Apocrine Gland Adenocarcinoma.

At the start of the examination, the veterinarian will ask you to describe the concerning symptoms and behaviors that you are noticing in your pet. Be certain to carefully explain every sign of discomfort that you may have noticed. This will help the veterinarian to reach an accurate diagnosis. A physical exam will also take place, at which time the veterinarian may discover a mass or lump in the perianal area.

If a tumor is found, the veterinarian may need to aspirate (insert a needle) into the mass to distinguish between cancerous cells and infection. This is the biopsy, and is often performed when your pet is awake or under a very quick acting injectable sedation. Blood tests, to assess the overall health of your dog as well as verify the presence of kidney trouble, will be performed. In addition, x-rays and ultrasound may be necessary in order to evaluate the lymph nodes and organs (such as kidneys, heart and lungs).

Early detection of anal gland cancer in dogs is best followed with aggressive treatment.

Surgery is the first option. If the tumor was discovered in the early stages and the spread to lymph nodes is limited, complete removal of the tumor is desirable. This provides the best possible outcome for your dog. The tumor is removed through an incision directly at the site of the mass. Large tumors may necessitate removal of additional tissue surrounding the mass. In 50% of the canine cases of Apocrine Gland Adenocarcinoma, enlarged lymph nodes are found in the abdomen. They can be removed at the same time as the primary tumor.

Chemotherapy may be the recommended second step, in order to prevent the spread of the disease. Radiation may be required also, particularly in cases where complete surgical removal cannot be realized. You may decide to have your veterinarian use the surgical approach only; however, the best way to improve the life expectancy of your dog will be with the additional treatments of chemotherapy and radiation. This is a conversation to have with your veterinarian, as each situation is different.  

If your pet has hypercalcemia, calcium lowering drugs and prednisone along with intravenous care, will be necessary prior to surgery.

Veterinary follow up is crucial to the continued health of your pet. Patients of anal gland cancer surgery and drug therapy require return visits to the clinic every 3 months for a period of 18 months. Biannual visits are important for the duration of your dog’s life.

Immediate care after surgery will involve your dog wearing an Elizabethan collar to prevent the tearing or infecting of the wound due to licking. Stool softening medication may be prescribed, and you will be instructed to limit the activity of your dog for a minimum of two weeks.

Fecal incontinence may be present in the weeks following surgery, but in most cases the problem will gradually be resolved. Continued kidney issues are a possibility which may necessitate a prescription for blood calcium reduction. The outcome of anal gland cancer depends greatly on your pet’s overall health and the size of the tumor upon discovery.

The veterinarian will likely want to do a complete tumor removal, surgically ($1,500-$3,800). The veterinarian may combine surgery with chemotherapy ($1,000 per treatment) to best avoid more growths throughout the body. If the tumor has spread to the lymph nodes or is rather large then complete surgical removal may not be an option. Radiation therapy ($2,000-$6,000) will likely be the best option to combat a large tumor that would be dangerous to remove. If your dog has been diagnosed with hypercalcemia, this will need to be treated before surgery. Treatment can consist of calcium lowering drugs, Prednisone ($40 per 100ct.) as well as, the use of intravenous fluid therapy ($40-$60).