Anal Sac Cancer in Dogs

Picture of a Sporting Dog

Both cats and dogs can develop anal sac cancer. Both species are equipped with a pair of anal sacs, which are typically located on either side of the anus. The sacs are have anal glands on the inside, which can cause a variety of problems, especially in our canine friends (particularly if they become impacted).

In today’s article, we’re looking at anal sac cancer — its causes, clinical signs, diagnosis, and treatment options, as well as whether you can prevent this condition or not. Read on to find out more.


Unfortunately, as is the case with many other types of cancer and that might affect a variety of other organs, it is yet unclear what might be at the root of the disease.

It’s generally acknowledged that cancer can be caused by a range of factors such as the food that the dog eats and how healthy it is or a genetic predisposition to developing cancer. For example, if your canine friend’s parents both had anal sac cancer, your puppy does have a chance of developing it at one point in his life, too.

Other environmental or circumstantial factors also have a say as to whether a dog develops anal sac cancer. There are oncogenic viruses out there, and if your pet comes in contact with one and his immune response isn’t up to par, he could get the disease.

However, almost in every case of cancer, the exact cause remains unclear. It is more common in middle-aged to senior dogs.


If your dog has an anal sac tumor, he might show some of the following clinical signs:

  • Blood in the feces
  • Straining to pass feces
  • Constant licking of his nether region
  • A visible or palpable lump close to the anus
  • Scooting on the ground (but this can also be seen if your dog has internal parasites, so it is not a specific symptom of the disease)

Sometimes, anal sac cancer can be so severe, and it might have spread to other organs to such an extent that the dog will show other symptoms of generalized diseases, such as vomiting, increased thirst and urination, lethargy, and muscle weakness.

Anal sac cancer can lead to kidney failure, so that is why some dogs exhibit a variety of urinary clinical signs.


Anal sac tumors have to be diagnosed as thoroughly as possible in order for the veterinarian to be able to set a course of the treatment and choose the appropriate therapy alongside yourself.

The biggest issue with most anal sac tumors is that they can spread quickly to other organs in a dog’s body. In fact, most anal sac/gland tumors are carcinomas, which have a massive malignancy rate compared to other types of cancer.

Most anal sac cancer cases are diagnosed during routine examinations. It is recommended that you take your canine friend to the vet clinic once or twice a year for regular check-ups whether there’s something wrong with him or not.

The most common diagnosis method currently utilized for anal sac cancer is a fine needle aspirate. The technique involves using a very, very fine needle attached to a syringe, with the help of which the veterinarian or cytologist retrieves a number of cells from the tumoral mass.

Other diagnostic methods that your vet can recommend in case the fine needle aspirate doesn’t prove to be effective are a biopsy and various imaging techniques such as an X-ray, for example.

It is paramount for the tumor to be diagnosed correctly, as well as its type, its size, and its malignancy potential, and the stage of development that it has reached. It’s also critical for the vet to determine whether it has spread to other organs, and if it’s malignant and not benign.

How Can Anal Sac Cancer in Dogs Be Treated?

There are three therapies available for all types of cancer these days: surgery, radiation therapy, and chemotherapy. The last and the first are usually associated with treating anal sac cancer, especially since radiation therapy can be rather painful.

Your veterinarian might recommend chemotherapy before your dog goes through the surgery, but given that the operation is not simple and the recovery process can be quite lengthy, chemotherapy is usually administered following the surgical procedure.

With the appropriate treatment, many dogs can continue to live for one year or more after being diagnosed with anal sac cancer.

Recovery Process

The biggest issue with anal sac cancer recovery is that the dog really has to behave and avoid touching the area where the operation was performed.

This means that your pooch will not only have to wear a so-called ‘cone of shame, but you’ll also have to keep an eye on him as best as possible so that no scooting on the ground happens.

Dogs can also infect the operation site if they constantly lick it, so that is another thing you have to prevent as best as possible.

If the patient has already developed kidney disease besides the anal sac cancer, he will also have to receive medication for that health problem.


The average life span of dogs that are operated and treated using chemotherapy is 16 to 18 months, but this is the case for animals that also have had their enlarged local lymph nodes removed.

If your dog is in overall great health condition and he is not suffering from any other chronic diseases that might put his life at risk because of the chemotherapy and surgical procedure, he can definitely live for more than 18 months.

Can Anal Sac Cancer Be Prevented?

The answer to this question is no. Anal sac or gland cancer can’t be prevented using any practical method, especially if your dog is genetically predisposed to the condition.

However, if you take your dog to the vet on a regular basis (at least once a year between the ages of 1 and 6/7 and then twice a year), the vet has a chance of diagnosing the condition before it metastasizes to other organs.



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