Anal Gland Cancer in Dogs

A Pet Owners Guide to Anal Gland Cancer in Dogs: Causes, Symptoms, and Treatment

Katelyn Son
By Katelyn Son
Medically reviewed by Jamie Freyer
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What is Anal Gland Adenocarcinoma?

What is Anal Gland Adenocarcinoma

Anal gland cancer in dogs is a type of cancer that starts in the cells of the dog’s anal glands or anal sacs. Anal sac cancer is rare and accounts for less than 1% of dog cancer cases. 

The anal sacs are pouches on each side of the anus, between the internal and external anal sphincter muscles. These pouches are lined with apocrine glands that produce a strong-smelling secretion deposited along with a dog’s feces.

Anal gland cancer in dogs usually affects one anal gland, but both sides can become cancerous. The most common tumor type is anal sac adenocarcinoma, a highly malignant tumor that can spread to other organs, including the sublumbar lymph nodes, lungs, and liver.

Over 50% of apocrine gland adenocarcinoma cases have already undergone metastasis by the time of diagnosis.

What Causes Adenocarcinoma in Dogs?

The exact cause of anal gland cancer or any other type of cancer is hard to pinpoint. In most cases, cancer is triggered by a combination of risk factors. Such factors for anal gland cancer in dogs include:

  • Genetics. The higher rates of anal gland cancer seen in certain dog breeds suggest that genetics play a role. Anal gland cancer is more common in German Shepherds, Cavalier King Charles Spaniels, Dachshunds, Cocker Spaniels, and Springer Spaniels.
  • Age. Like most types of cancer, anal sac carcinoma is more common in older dogs. The average age of diagnosis is ten years old. However, anal gland tumors can also occur in younger dogs and adults.
  • Sex. Anal gland cancer in dogs occurs in both males and females. According to a study, it tends to be more common in female dogs (56% of the dogs with anal gland tumors were females). However, the study mentions there is conflicting information about gender predisposition. 

What are the Symptoms of  Anal Gland Cancer in Dogs? 

What are the Symptoms of  Anal Gland Cancer in Dogs

Anal gland cancer in dogs tends to grow inward, thus causing a delayed onset of clinical signs and symptoms. Here are some of the signs pet owners might notice in the advanced stages:

  • Swelling around the anal area
  • Ulceration and bleeding
  • Straining during bowel movements
  • Thin ribbon-shaped stools
  • Painful defecation.

According to DVSC, anal gland cancer in dogs results in hypercalcemia (high blood calcium levels) in 25% to 90% of cases. The elevated calcium levels are triggered by abnormal secretion of the parathyroid-related hormones by the cancerous cells and can cause:

  • Increased thirst and urination
  • Lethargy and general weakness
  • Vomiting.

If your dog is showing some of these signs, it is advisable to seek veterinary attention as soon as possible. By the time clinical signs are evident, anal gland cancer is often already advanced.

Diagnosing  Anal Gland Adenocarcinoma in Dogs 

The veterinarian will start with a physical examination and then focus on the anal gland tumor. An essential part of the physical exam is the rectal palpation (the vet inserts a finger into the dog’s rectum to feel the tumor).

To reach a definitive diagnosis, the vet will perform a fine-needle aspiration and/or biopsy. Fine needle aspiration is when the vet extracts a sample of your dog’s tumor cells and examines them under a microscope. A biopsy involves the excision of a larger tissue sample from the tumor to look for cancer indications.

Bloodwork might be necessary to check blood calcium levels. X-rays or radiographs may be done to determine if cancer has spread to other tissues and organs. Other tests your vet might perform include abdominal ultrasound, CT scans, and MRI.

What is the Best Treatment for Adenocarcinoma?

What is the Best Treatment for Adenocarcinoma

Cancer in dogs treatment is a complex process that often involves various treatments. Available treatments for adenocarcinoma are surgery, chemotherapy, and radiation therapy.

Surgery. Surgical removal of the anal glands (anal sacculectomy) is the gold standard for treating anal gland cancer in dogs. If the anal gland cancer has spread to the regional lymph nodes, they will also be removed during the procedure. Surgery may also be recommended for palliative reasons – removing the primary tumor can improve the dog’s quality of life. According to Brisbane Pet Surgery, fecal incontinence is a common side effect of the procedure.

Radiation Therapy. Radiotherapy is also an effective treatment option for anal gland cancer, especially in combination with surgery. It may be offered before surgery to shrink the tumor or after the surgery to destroy residual cells.

Chemotherapy. For anal sac tumors that have spread, chemotherapy is the best option, but it rarely yields the same results as surgery. Chemotherapy produces the best results when used in conjunction with surgery.

Ask your vet about holistic treatment options that can help your dog. Some of the effective ones include diet, physical activity, physiotherapy, acupuncture, herbs, and CBD.

Diet. Diet might especially be important for dogs with high calcium levels. Your vet or a veterinary nutritionist should be able to tell you which foods will help manage your dog’s calcium levels.

Cannabidiol (CBD) Oil. CBD has many benefits for a dog with cancer, including anti-anxiety, anti-inflammatory, and anti-pain properties. When choosing CBD for your dog, opt for a pet-safe vet-approved brand like the Honest Paws CBD Relief Collection. The collection contains bites and two balms, all formulated with full-spectrum hemp-derived CBD to support your dog’s health.

What can I do to Prevent Anal Gland Cancer in Dogs?

The question of how to prevent cancer in dogs is a tricky one. Anal gland cancer in dogs is a complex condition. Here are some of the things you can do to minimize your dog’s risk of getting an anal gland tumor: 

  • Provide a Healthy Diet. Healthy eating patterns have been shown to minimize the risk of getting chronic diseases, including cancer. Add some occasional pet-safe fruits and vegetables to your dog’s diet for their antioxidant properties.
  • Maintain a Healthy Weight. Your dog’s diet should also support a healthy weight. Obesity has been linked to an increased risk of chronic disease, including cancer.
  • Regular Vet Checkups. See your veterinarian at least twice a year to ensure your dog stays in optimal health. Anal gland cancer in dogs is often diagnosed on routine rectal examinations.

If your dog is diagnosed with anal gland cancer, you have to start treatment immediately. However, the treatment can be costly, with surgery costing up to $7000.

To prepare for such an event, get a good insurance plan like the one from OneVet. With the OneVet plan, you get 24/7 access to a licensed veterinarian, $3000 in emergency funds, and coverage for all preexisting conditions for up to six pets, all for $19.99.

How Long Can a Dog Live After Being Diagnosed With Adenocarcinoma?

How Long Can a Dog Live After Being Diagnosed With Adenocarcinoma

The median survival time for dogs with anal gland adenocarcinoma is between 12 and 24 months. Dogs whose anal gland tumors are successfully removed can live for up to four years, but this is usually when the cancer is caught very early.

Survival time for dogs with cancer is highly dependent on the type of tumor, size of the tumor, stage of cancer, and quality of treatment.