Anal Cancer in Dogs

Anal cancer is relatively rare in dogs, but it is nevertheless a serious form of the disease. Anal cancer spreads quickly, and can be difficult to treat. Read on to learn more about this aggressive form of cancer, how its treated, and what the prognosis is.

Causes of Canine Anal Cancer

Vets aren't sure what causes this particular type of cancer, though they believe it may have something to do with parathyroid gland imbalance. Dogs of all breeds and ages appear to be equally prone to anal cancer. Dogs with hypercalcemia, or elevated blood calcium levels, may also be more likely to develop it.

Symptoms of Anal Cancer in Dogs

The most visible symptom of anal cancer in dogs is the appearance of a growth on or near the anus. Anal cancer tumors are usually rather small, but they can still make it difficult for your dog to move his bowels. Dogs with anal cancer may become constipated or struggle to move their bowels, they may stop eating and lose weight, and they may appear excessively thirsty. Often, they also become listless and lethargic.

Diagnosing Anal Cancer in Dogs

Your vet will need a complete medical history and a thorough physical exam in order to diagnose anal cancer in your dog. A biopsy of the abnormal tissue can tell your vet whether or not the tumor is cancerous. Often, vets can get enough tissue for a biopsy by using a fine needle aspirate, but sometimes more tissue than what can be withdrawn through a needle may be needed. If that's that case, then your vet will excise tissue with a scalpel.

Ultrasounds or X-rays can usually tell your vet if the cancer has already spread. 

Treating Anal Cancer in Dogs

If your dog develops anal cancer, your vet will probably recommend surgical removal of the tumor. Your vet will also need to remove any lymph nodes that have been affected by the cancer. Your dog will also probably need radiation therapy, to keep the cancer from coming back. If your dog's cancer has already spread, radiation therapy or chemotherapy can help slow or stop the progression of the cancer, though cancer is always much harder to treat after it has spread.

Anal cancer in dogs usually carries a very poor prognosis. However, you can improve your dog's prognosis by having him treated promptly and properly. After treatment begins, monitor your dog closely for any signs that the cancer has come back. Your vet will probably recommend regular physical exams, X-rays, ultrasounds, and blood work to help monitor your dog for the recurrence of anal cancer tumors. Proper treatment and post-treatment supervision can help enhance your dog's chances of surviving anal cancer.

Anal cancer is difficult to prevent, since vets don't know what causes it. If your dog develops any signs of constipation accompanied by growths or swellings of the anal area, see your vet right away. The earlier anal cancer is diagnosed, the greater your dog's chances of recovery.