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Anal Gland Cancer in Dogs (Anal Sac Adenocarcinoma)

What Is Anal Gland Cancer in Dogs?

Anal gland adenocarcinoma is the most prevalent form of anal gland cancer observed in dogs. Adenocarcinomas originate from glands. Situated on each side of a dog’s anus, the anal glands serve as scent glands. During defecation, these glands release a small amount of malodorous substance, aiding dogs in marking their territory. The secretions from the anal glands are stored in the anal sacs.

Cancer can develop in the apocrine (sweat) glands linked to the anal sac. Typically, this cancer manifests as a mass that veterinarians may detect through a rectal examination.

Symptoms and Types

Signs of anal cancer in dogs can manifest through various symptoms:

  • Discomfort in the perianal region
  • Presence of anal discharge
  • Scooting behavior across the floor
  • Excessive licking around the perianal area
  • Difficulty or straining during bowel movements
  • Episodes of constipation

Detection of anal gland cancer at home might prove challenging. Instead, identification often occurs during routine veterinary examinations. If the tumor grows significantly, it may appear as swelling in the anal region, potentially impeding the dog’s ability to defecate and causing ribbon-shaped stool.

Approximately 25% of anal gland adenocarcinoma cases in dogs are associated with elevated blood calcium levels. Elevated calcium levels can result in increased thirst and urination, alongside decreased energy levels and appetite. Failure to address heightened calcium levels medically poses risks of kidney failure or damage to your dog’s health.


The precise cause of anal gland cancer in dogs remains unidentified. This type of cancer can impact both male and female dogs. It is more frequently diagnosed in certain breeds, including:

  • German Shepherd
  • Alaskan Malamute
  • Dachshund

Spaniel family breeds such as:

  • English Cocker Spaniel
  • Cavalier King Charles Spaniel
  • Springer Spaniel


Diagnosis of anal gland cancer in dogs typically occurs when a veterinarian detects a mass during a rectal examination or when swelling in the anal region is observed, indicating the presence of a mass.

To confirm the presence of anal gland cancer in your dog, the veterinarian will perform a procedure known as a fine needle aspirate. This involves inserting a thin needle into the affected gland to extract a small sample of cells, which are then examined under a microscope.

If cancer is still suspected following the fine needle aspirate, the diagnosis will be confirmed and the specific type of cancer determined through a biopsy with histopathology. This procedure involves collecting additional cells for close examination. Additionally, bloodwork, abdominal ultrasound, and chest x-rays may be recommended. Bloodwork assesses the overall health of your dog’s organs and checks for elevated calcium levels, which can be indicative of cancer.

Chest x-rays are used to identify cancer that may have spread to the lungs or nearby organs. An abdominal ultrasound helps determine if the cancer has spread to internal organs and lymph nodes. Upon diagnosis of anal sac cancer, consultation with a board-certified veterinary oncologist is strongly advised.


Upon diagnosing anal gland cancer in dogs, it is typically advised to opt for surgical removal of the anal gland and sac. This procedure aims to extend your dog’s lifespan and reduce heightened calcium levels by eliminating the tumor.

In instances where the cancer has disseminated to nearby lymph nodes, surgical removal of these nodes is also commonly recommended.

If the cancer has already metastasized to other parts of your dog’s body, surgery to extract the anal gland mass may still be undertaken to enhance your dog’s comfort, albeit it might not necessarily prolong their lifespan.

Living and Management

Chemotherapy is often advised to hinder further spread or recurrence. If surgery is not viable, radiation therapy might be suggested to reduce the size of your dog’s tumor.

Anal Gland Cancer in Dogs FAQs

What is the life expectancy for dogs with anal gland adenocarcinoma?If the tumor is surgically removed and there is no evidence of metastasis, dogs can live for 1-2 years.

How aggressive is anal gland cancer in dogs?Anal gland adenocarcinomas are highly aggressive and infiltrate surrounding tissues. They also have a high tendency to metastasize. Typically, anal cancer in dogs spreads to local lymph nodes initially.

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