What Is Perianal Fistulas In Dogs?

Perianal (more generally anal) fistula is a chronic disease that a large number of dogs suffer from. It is defined as a lesion affecting the anal area of ​​the dog.

It is a serious and painful condition which, by extension, can affect the anus and rectum. Also called anal furunculosis, this disease affects, in particular, German Shepherds.

What is a perianal fistula?

The perianal fistula is a painful and difficult condition to treat. This is an abnormal duct connecting the anus to its periphery. It affects, as we have said, the anal area, but can also extend over several Inches, on the skin of the dog.

The causes

There is no precise cause for this disease, but several elements seem to be involved:

  • immune system dysfunction
  • infection of the anal glands or sebaceous glands (those around the anus)
  • heredity (80% of affected dogs are German Shepherds)
  • moisture in the anal area
  • a food allergy
  • certain hormonal conditions such as hypothyroidism
  • poor dog hygiene
  • age (this pathology is very common in dogs from 4 to 7 years old)


The symptoms of perianal fistula are usually visible. We note:

  • Pain in the anus
  • Bloody losses
  • Faecal incontinence
  • Excessive licking around the anal area
  • Loss of appetite
  • A characteristic odor due to infection

The diagnosis

The diagnosis is based on the dog’s report as well as the signs observed. The veterinarian may need to view the colon using a camera (colonoscopy) to validate the diagnosis of the disease. Then he can take a biopsy, in case he suspects there is a tumor in the anal area.


There are two types of treatment for dogs with perianal fistula. We find the surgical treatment which basically aims to extract the affected tissues and prevent their extension on the skin of the animal. But the surgery can cause certain complications such as fecal incontinence or the narrowing of the size of the anus, which is why veterinarians only resort to it in certain specific or very serious cases.

They often opt for medical treatment at first. This consists of treating the lesions with oral or cutaneous medications, changing the dog’s diet in favor of hypoallergenic food, in order to prevent and avoid allergies. Finally, medical treatment also aims to maintain good hygiene in the affected area of the dog. It should be shaved, clean, and dry.

Perianal fistula is painful and difficult to treat. Many breeders choose to euthanize their dogs to avoid seeing them suffer and to avoid the high cost of treatment. Please note that your pet’s health insurance could help. It is a disease that requires a lot of patience and persistence, but a lasting cure is possible.

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