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What is Perianal Fistula?

Tunnel-like formations in your dog’s skin and deeper tissues in the surrounding area of your dog’s anus are called perianal fistulas. These lesions can be minor or more serious; they begin as small holes in your dog’s skin and then can become wide and deep and can ultimately surround your dog’s anus in its entirety. This condition is most likely to occur in German Shepherds, though it can happen in any breed. 

Perianal fistulas can cause a great deal of pain and discomfort in your dog. Dogs that experience a perianal fistula may also have chronic diarrhea as a result of inflammatory bowel disease; it is thought that these two conditions may be connected.

Perianal fistula, which is also known as anal furunculosis, occurs when a dog experiences chronic lesions around their anus that worsen, leading to deep ulcers that drain and are painful to the dog.

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Symptoms of Perianal Fistula in Dogs

Should your dog have a perianal fistula, you may observe the following:

  • He is experiencing pain when defecating
  • He is struggling to defecate
  • He is constipated and/or experiencing diarrhea
  • Mucus or blood in his stools
  • Extensive licking and biting of his anus
  • He may appear restless and cry out when he is about to have a bowel movement.
  • Should you try to lift his tail he may struggle or bite.

Types 

A dog can experience a mild perianal fistula or his condition may be moderate or severe.

Causes of Perianal Fistula in Dogs

The exact reason that perianal fistulas occur is not known. It is thought that the condition begins as inflammation of the sweat and oil glands that are in and around your dog’s anus. This then results in an infection of the area, which can then lead to abscesses that open and drain. The area under the tail and around the anus is warm and moist, which makes it easy for bacteria to multiply.

While perianal fistulas most often affect German Shepherds, they can occur in any breed of dog. German Shepherds often carry their tail low between their hip bones, which will cover their anus; it is thought this may predispose them to this condition. Because German Shepherds are more often affected, genetics may play a role in the condition developing.

Diagnosis of Perianal Fistula in Dogs

Should you notice any of these symptoms in your dog, you will want to schedule an appointment with your veterinarian. In addition to asking you for information regarding the symptoms you have seen in your dog and when you first noticed them, your veterinarian will conduct a physical examination. This will include a rectal exam because perianal fistulas may be caused by an infection or blockage of the anal sacs. Some dogs will need to be sedated in order for the exam to be conducted. Your veterinarian will obtain samples of cells or tissues from the anal sacs or fistula which can be looked at under a microscope or used for bacterial culture and sensitivity testing.

Treatment of Perianal Fistula in Dogs

Your veterinarian will likely consider providing both medical and surgical treatments as 80% of those experiencing perianal fistulas will experience a recurrence of the condition. When the condition is relatively mild, your veterinarian may clip any hair in the anal area and cleanse the area with an antiseptic solution and then flush the area with water. Should the condition be more severe, treatment options include:

  • Modifications in your dog’s diet (a novel protein diet)
  • Antibiotics (for example metronidazole)
  • A combination of oral cyclosporine and ketoconazole
  • Administration of oral anti-inflammatory and immunosuppressive medications like prednisone (this has been less effective than cyclosporine and ketoconazole)
  • Topical immunosuppressive medications

Treatment will usually take place for 7-9 weeks, though recurrence is typical once treatment is stopped, particularly in dogs with moderate disease.

Your veterinarian may also consider surgical treatment which will include removing any affected tissue, whether through freezing it, cautery or laser surgery. Anal sacs may also be removed during surgery. In some cases, the veterinarian may recommend removing the tail as it may help with keeping the area clean and aerated, which will assist with healing of current fistulas and decrease the chance that the condition will recur.

Recovery of Perianal Fistula in Dogs

Should a dog undergo cryosurgery or laser surgery he will have open wounds for a few weeks. These will need to be cleaned daily and dead tissue, bacterial and fecal material will have to be removed. Your veterinarian will likely recommend that your dog take stool softeners to help your dog not experience pain when having a bowel movement. An e-collar will likely be necessary so that your dog does not cause harm to the wounds.

The condition will often have to be managed over the course of your dog’s life, through diets and medication (immune suppressants). In cases where the dog experiences chronic damage to the perianal area, whether from the fistulas or after surgeries, it can impact the area’s nerves, which can cause fecal incontinence.

Perianal Fistula Questions and Advice from Veterinary Professionals

Beau
German Shepherd Dog
6 Years
Moderate condition
1 found helpful
Moderate condition

Hi, my gsd Beau is on Atopica 100mg daily,but she has lost so much weight although she eats well. She poos a lot and often eats it. Is there anything I can feed her to put weight on (she eats complete food plus chicken or fresh whole sardines or tinned meat). Is there any other medication options.
Many thanks
Issy
Many thanks

Dr. Callum Turner, DVM
Dr. Callum Turner, DVM
2466 Recommendations
If Beau is on a complete diet which is supplemented with Chicken, then there are a few possibilities it why she is losing weight including parasites, malabsorption, hormonal conditions, pancreatic disorders among other causes; I do not think any weight gain supplements would be beneficial for her if she isn’t gaining weight on her current diet, you should visit your Veterinarian to determine if there is any underlying cause for the weight loss. Regards Dr Callum Turner DVM

Thank you for prompt reply. If it's malabsorption what can be done to help this?
Thanks issy

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Ponyo
German sphepherd
6 Months
Fair condition
0 found helpful
Fair condition

I rescue a 6 month old female germen shepherd and notice a red opening next to her anus. Is it possible it is a perianal fistula? She has problems pooing in one place, she poos a little then walks a little then poos a little and walks again little again and poos again. She like to hide to pee and poo. I tried to train he but it has been difficult, she likes her privacy. She is going to be nurtured in December and was wondering can it be done at the same time to minimize the pain for her. Please advise.

Thank you

Dr. Callum Turner, DVM
Dr. Callum Turner, DVM
2466 Recommendations
If Ponyo has a perianal fistula or another issue around that area it may be surgically corrected at the same time as the spay; but you should visit your Veterinarian beforehand to examine Ponyo so they can diagnose the problem and to plan the surgery before she goes in. In the meantime try to see Ponyo some plain canned pumpkin to try to loosen her stool to make defecation easier. Regards Dr Callum Turner DVM

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Whity
Labrador Retriever
6 Years
Critical condition
0 found helpful
Critical condition

How many months it will take to cure large anus wounds in lab dog ...??? Is it fully curable...any wound scars remain......cost of treatment per day.....any ideas to cure in easy way

Dr. Callum Turner, DVM
Dr. Callum Turner, DVM
2466 Recommendations
The treatment and timeframe for recovery would be dependent on the severity and the origin of the original wound; wounds around the anus may be caused by trauma, tumours, fistulas or tearing of the anal sphincter. If there is a perianal fistula or an anal gland issue then surgical correction would be required to correct the issue; smaller wounds from scratching or other trauma may require conservative treatment. Without carrying out a thorough examination I cannot commit to any course of treatment and the cost of treatment would be dependent on the original condition, severity and your location (cost of Veterinary care varies widely depending on location); it would be best to visit your Veterinarian for an examination who will be able to advise you about Whity’s specific case. Regards Dr Callum Turner DVM

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Haydn
German Shepherd
11 Years
Moderate condition
0 found helpful
Moderate condition

Has Symptoms

Straining To Defecate
Straining To Defecate
straining to defecate, blood around anus

My German Shepherd has perianal fistulas. He has been on a combination of oral cyclosporine and ketoconazole for about 7 weeks and is much better. The medication is very expensive and I was thinking of giving him the cyclosporine once a day instead of twice for a few weeks and see if he continues to be OK. This obviously will reduce the cost of his treatment. My vet says he will have to stay on this medication for the rest of his life. The vet also suggests I put him on a hyper-allergic food. What do you think I should do?

Dr. Callum Turner, DVM
Dr. Callum Turner, DVM
2466 Recommendations

Perianal fistulas are unpleasant for dog, owner and Veterinarian as the treatment and management may be unrewarding and frustrating at times. I cannot recommend reducing the dosage of cyclosporine as it is a prescription medication and Hayden is not under my duty of care (I haven’t examined him) and there is the minimum effective dose to be considered too; but dietary changes, immunosuppressive therapy and antibiotic therapy are the normal course of medical treatment which may be coupled with surgical treatment to get the best result, recurrence is common in dogs and recurrence rates are around 80%. Regards Dr Callum Turner DVM
www.acvs.org/small-animal/perianal-fistulas
www.merckvetmanual.com/digestive-system/diseases-of-the-rectum-and-anus/perianal-fistula

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