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Perianal Fistula FAQs

By Edited Jul 24, 2016 0 0

Chances are, if your dog has a perianal fistula, you will know it.

According to Dr. Cathy Alinovi of Hoofstock Veterinary Services, fistulas are incredibly painful for your pet.

In this exclusive interview session, she answers some of the most commonly asked questions about fistulas and offers some dog health tips for pet owners.

Dr. Cathy Alinovi
Credit: Image provided by and used with permission of Dr. Cathy Alinovi, Copyright 2012, all rights reserved

Donna Cosmato (DC): What are perianal fistulas?

Dr. Cathy: Perianal fistulas are inflammations occurring in the skin around the rectum and may also be referred to as:

  • Anorectal abscesses
  • Perineal fistulae
  • Perianal fissures
  • Perianal sinuses

DC: What causes them?

Dr. Cathy: The cause of perianal fistulas is not fully known but it is suspected to be an autoimmune condition. It is also suspected to be a genetic issue since it occurs primarily in German Shepherd dogs. German Shepherds have more apocrine sweat glands than other dogs – the apocrine glands are the ones that make smelly, oily, sweaty discharge, whereas regular sweat glands produce watery discharge.

In fact, 80% of dogs with perianal fistulas are German Shepherds, and most affected dogs are males over five years old.

DC: What signs or symptoms would alert me that my dog has perianal fistulas?

Dr. Cathy: Perianal fistulas look like deep cracks and crevices that ooze smelly pus and discharge in the area around the rectum. Dogs with perianal fistulas smell bad under their tail or may spend a lot of time itching and chewing their rectum. They may scoot and they may scream or run if their human friend tries to lift their tail and look underneath. Fistulas get worse and better with time. These dogs may have constipation and/or diarrhea, or these symptoms may alternate.

DC: How does the vet make a diagnosis of this condition?

Dr.  Cathy: A biopsy (sample of tissue that is surgically obtained) of the perineal tissue provides diagnosis of perianal fistulas. Other things that must be differentiated from perianal fistulas are

  1. Cancer of the anus (squamous cell carcinoma)
  2. Hyperplastic anus
  3. Perianal adenoma (benign tumor)
  4. Anal sac rupture

Biopsy differentiates between all of these.

DC: What are the treatment options?

Dr. Cathy: The most important thing to realize is this ailment takes time to treat and flare-ups are common. Treatment can be medical or surgical. Medical treatment can be conventional or alternative; conventional medical treatment includes: 

  • Antibiotics
  • Stool softeners
  • Immune suppressive drugs
  • An anti-inflammatory diet

Some options include:

  1. Antibiotics are used when the fistula is oozing pus or has formed an abscess.
  2. Stool softeners make defecation less painful and are recommended for quality of life.
  3. Immune suppressive drugs such as prednisone, cyclosporine, and/or azathioprine can help quite a bit to reduce the pain and inflammation.

About Medications

Remember, these drugs suppress the immune system, so the dog is at higher risk of secondary infections; additionally, some of these drugs have pretty nasty side effects.

These medications may be used in combination with metronidazole or ketoconazole, which can also have side effects.

Tacrolimus, which modulates the immune system, can be applied topically to the region (if the dog isn’t too sore to tolerate it) to help with the symptoms.  Regardless of the medication, monitoring is highly recommended so potential side effects don’t get out of control.


Feeding an anti-inflammatory diet is one big thing pet parents can do for their dogs with perianal fistulas. These diets are usually made from unusual proteins that the dog has hopefully never eaten before. Typically, these diets include:

  • Rabbit
  • Duck
  • Kangaroo
  • Fish
  • Venison

Many of the prescription food lines have these purported “allergy” diets. Please keep in mind that these diets are still highly processed, especially the dry diets, and may still cause immune-related overstimulation.

DC: What’s your opinion about using natural treatments or dietary modifications?

Dr. Cathy: As mentioned above, diet plays a huge role in treating perianal fistulas. I suggest to my clients to prepare foods at home using cooling foods like turkey, rabbit, fish, pears, and cucumber and to consider feeding them raw, as raw foods cool as well. Fistulas are hot—just rest your hand over the area—it’s hot!

Changing the diet helps tremendously to decrease inflammation (the perineal region is definitely inflamed with fistulas). Other things to decrease inflammation include detoxification for heavy metals, intestinal parasites, yeast and other causes of leaky gut  such as intestinal dysbiosis.

Other modalities, which may be helpful in treating fistulas, are homeopathy or Ayurvedic medicine. Regardless of the modality chosen, treating perianal fistulas is tough and time-consuming. Be patient and stick with it, keeping your baby as comfortable as possible.

DC: What happens if the vet has to remove the fistulas?

Dr. Cathy: Surgical treatment is still used commonly in humans with perianal fistulas, however, it is really only used in dogs when medical treatment is not enough. In dogs, the goal of surgery is to remove any stricture or scar tissue; surgery is also needed if the fistula extends to the anal glands. Laser surgery has been successful in controlling pain and preventing recurrence; however, 20 percent of these patients end up with fecal incontinence.

DC: Will my dog need special care or a special diet after surgery?

Dr. Cathy: Stool softeners are probably the most important things after surgery as there is a need for time for things to heal without creating a huge pain syndrome or damaging the surgery site.  The perineum will need to be cleaned daily by the owner because the dog will probably wear a cone or a donut so as to not over-clean the area.

Complications of surgery are fecal incontinence, restricted anus, and no improvement of the fistulations.

DC: What is the prognosis for these dogs?

Dr. Cathy: Not great – recurrence is common and because this condition can be so painful for the dog, owners often worry about the dog’s quality of life.

DC: What can pet parents do to prevent their dogs from developing perianal fistulas?

Dr. Cathy: Because the causes are not known, this question is difficult to answer. However, as fistulas are inflammation going wrong, reducing any inflammation in our dog’s lives should help reduce the risk of perianal fistulae. This means:

  • Feeding a high quality, meat-based diet (no corn, no dyes, no by-products, preferably real food)
  • Avoiding overuse of medications and vaccinations

Fistulas in Dogs

If you suspect your dog has a perianal fistula, consult your veterinarian as soon as possible because early intervention and treatment is critical to your pet.

This information is provided for educational purposes only and is not intended to diagnosis or treat any dog health problems. While the information is deemed factual and reliable, no warranties either expressed or implied are made.



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