Anal Gland Cancer In Cocker Spaniels

The anal sacs are two glands located immediately inside the rectum (in the clock-face position of 4 & 8 o'clock),  they produce territorial marking secretions which are expelled in small quantities with each bowel movement. Anal gland tumours can be benign (anal sac adenomas) or malignant (anal sac adenocarcinomas), the commonest form of tumour is malignant.

Photo courtesy Vet Surgery Central Inc

What are the symptoms of anal gland tumours?

Symptoms very depending on the size of the tumour and whether hypercalcemia has occurred (tumours often produce a hormone which causes blood calcium levels to rise above normal levels). Common symptoms include:

• Straining to pass stools
• "Ribbon-like" stools
• Swelling/protrusion around the anus
• Increased thirst/increased urination
• Decreased appetite/weight loss
• Muscle weakness/low heart rate
• Vomiting
• Stilted walking/back pain

Diagnosis

Diagnosis is confirmed by rectal palpation followed by a complete blood count, serum chemistry profile and urine analysis which will identify hypercalcemia. Aspiration biopsy is useful, this will provide cells from the tumour which can be microscopically examined for signs of malignancy and tumour identification. Additionally, X-Ray and ultrasound of the tummy may be performed to check the internal organs and look for evidence of metastasis (the spreading of a disease (especially cancer) to another part of the body).

Ultimately the tumour can be surgically removed or by taking a biopsy with tissue samples being sent for histopathologic examination.

How are anal gland tumours treated?

The preferred treatment option is surgical removal of the tumour and any affected lymph nodes (sublumbar lymph nodes). Chemotherapy is recommended following surgery to kill any remaining cancer cells, additionally radiotherapy may prove beneficial. Hypercalcemia will resolve without treatment once the tumour is removed.

Prognosis

In cases where diagnosis is swift & surgery is also undertaken swiftly, providing the cancer has not spread, the outlook for the dog is reasonably good with life-span relatively normal or only marginally reduced.  Long-term chances of survival are increased by chemotherapy/radiation treatment.