Anal glands are scent glands found in the region of the anus which can become cancerous.

Treatment typically involves both surgical removal of the tumor and chemotherapy.

Recovery from this type of surgery typically is quick and complications are infrequent.

Prognosis is improved with early detection and treatment of the tumor.

What is it?

• This type of cancer affects the anal scent glands in dogs and cats
• The cancer usually is malignant and has a high tendency to spread to other parts of the body
• If it spreads the liver and the lymph nodes are commonly affected, however, the tumor can also spread to the lungs

Pertinent Anatomy

• The anal sacs are a pair of scent glands located along side of the anus
• The secretion from the glands is foul smelling and is excreted in small amounts on the feces during bowel movements to mark a pet's territory

Clinical Signs

• Your pet may have no signs of a problem and your pet's veterinarian may find a mass in the anal sac during a routine physical examination
• Some tumors cause the calcium levels in the blood to become elevated and signs of this include: increased thirst
• Increased urination
• Decreased activity
• Decreased appetite
• Weight loss
• Vomiting
• Muscle weakness
• Low heart rate
• If the tumor is large signs may include: swelling of the anal region on the affected side
• Straining to during bowel movement
• Thin ribbon shaped stools
• Difficulty passing urine
• Arched back due to pain associated with spread of the tumor to the spine

Diagnosis

• Rectal palpation will confirm a mass
• Confirmation of the type of tumor necessitates a biopsy, which is frequently done after the tumor has been removed
• Tests done prior to surgery may include complete blood count
• Extensive blood chemistry profile to check internal organ health
• Urinalysis
• Chest x-rays
• Abdominal x-rays
• Abdominal ultrasound

Treatment

• Surgical removal of the anal sac and its associated tumor
• Surgical removal of the lymph nodes if the tumor has spread to regional lymph nodes
• Chemotherapy is usually recommended if the tumor is malignant
• Radiation therapy may be indicated if the margins are not complete

Potential Complications

• Anesthetic death is very uncommon
• Fecal incontinence is very uncommon unless both anal sacs have tumors and are removed; even then we find the risk for fecal incontinence to be low
• If the lymph nodes are large and are removed, urinary incontinence may be present, usually for a few days
• Recurrence of tumor
• Spread of cancer
• Infection is very uncommon
• Rectal prolapse from excessive straining

Aftercare

• Limit activity for 3 weeks
• Check the incision daily for signs of infection; administer antibiotics if prescribed by the surgeon
• Monitor for straining during bowel movements - if needed a stool softener may be prescribed

Prognosis

• The prognosis is highly variable
• We have seen many dogs that live tumor-free for a number of years after treatment with surgery and chemotherapy
• Better prognosis if the tumor is small and no evidence of spread is present