Rectal Tumors in Dogs

By Jane Meggitt

While it's not the most pleasant part of pet ownership, keeping track of your dog's defecation behavior and output is important. That's because changes in his elimination habits or his feces could signal various internal problems, including canine rectal tumors. Take your dog to the veterinarian for a checkup if he exhibits any changes in his daily constitutional.

Rectal and Anal Gland Tumors

Rectal tumors occur more often in middle-age to older male dogs, although any canine can develop these masses. Rectal tumors generally develop within the large intestine or at the midpoint or end of the rectum, near the anus. Benign tumors, or polyps, usually occur in the rectum's end. While most rectal tumors are inside the bowels and are not visible, an initial sign of anal gland cancer in a canine is a mass near the anus. Female dogs are equally vulnerable to anal gland or sac tumors. Certain breeds, including German shepherds, springer and cocker spaniels, malamutes and dachshunds, have higher rates of anal gland carcinoma.

Rectal Tumor Symptoms

Dogs suffering from rectal tumors usually have difficulty defecating. You might also see blood in the feces. Straining may accompany symptoms that include obvious pain while defecating including whimpering or yelping, mucus in the feces, diarrhea or constipation. Other symptoms include weight loss, lethargy, vomiting, dehydration, rectal bleeding and abdominal pain.

Rectal Tumor Diagnosis

Your vet diagnoses a rectal tumor via palpation of the rectum and abdomen, along with blood tests, an endoscopy -- sending a tiny camera into your pet's bowels to photograph the interior -- X-rays and ultrasounds. In cases of anal gland tumors, the vet will perform a biopsy of the mass by inserting a fine needle and extracting cells for testing.

Rectal Tumor Treatment

While most canine rectal tumors require surgical removal, the procedure might be too little, too late. That's because, by the time the tumor is discovered, any cancer may have already spread. However, not all rectal tumors are malignant. Up to half of rectal tumors are benign. If your dog does have cancer, your vet might recommend chemotherapy or radiation as additional therapies to prolong your dog's life. Average survival times for dogs with rectal cancer depend on the type of tumor. These times range widely, from 32 months for dogs with pedunculated tumors, or those growing on stalks, to just over a month for dogs with annular, or encircling, tumors.