Understanding Oronasal Fistula in Dogs: Causes, Signs, and Treatment

The term oronasal fistula (ONF) may seem unfamiliar to many dog owners, but it is a common condition affecting many dogs. Dogs with this condition have an abnormal connection between their oral cavity and nasal cavity. Consequently, when the dog eats or drinks, food and liquids enter the nasal passage, resulting in nasal discharge, coughing, sneezing, secondary infections, and nearly always marked discomfort. Imagine how unpleasant it would be to have food or liquid stuck up your nose whenever you eat or drink. Ouch! In order to provide peace of mind and promote the well-being of our canine companions, it is important to understand the causes, signs, and treatment of oronasal fistulas.

An Oronasal Fistula in a dog. This is where the canine tooth (fang) should be.


Causes of Oronasal Fistula in Dogs

There are multiple potential causes of oronasal fistulas in dogs, including:

Trauma: A sudden injury to the mouth or face can result in the development of a fistula. While we most commonly see oronasal fistulas as a result of dog bites, any trauma could cause an oronasal fistula.

Dental Disease: Advanced periodontal disease can lead to the loss of bone supporting the teeth, particularly the upper canines and incisors, creating an opening into the nasal cavity. In our practice, this is the most common cause. Dachshunds seem to be poster children for ONFs although all small breeds are prone.

Extraction Complications: Incorrect or complicated tooth extractions, patients self-traumatizing themselves, or sometimes just bad luck or poor healing can lead to fistula formation.

Congenital Causes: Some dogs are born with an oronasal fistula, though this is rarer than acquired causes.

Tumors: Growth or malignancies in the oral or nasal cavity can sometimes lead to fistula formation.


Signs of an Oronasal Fistula

Dogs with an oronasal fistula might exhibit:

  • Nasal discharge, especially after eating or drinking
  • Sneezing or reverse sneezing
  • Chronic nasal infections
  • Sinusitis
  • Bad breath
  • Coughing due to aspiration of food or fluids

If you notice any of these signs in your dog, it’s time to visit the vet’s office. Most often, your vet will recommend that you see a board certified veterinary dentist or oral surgeon to carry out the diagnosis and procedure.


Diagnosis of Oronasal Fistula

In some cases, a physical examination may be sufficient for the purpose of making a diagnosis, however, in the majority of cases, general anesthesia and an examination of the suspected site of injury are required. Additionally, X-rays and or other sophisticated imaging techniques, such as CT, may be beneficial in certain circumstances.


Repairing an Oronasal Fistula

Surgical repair is his preferred treatment for ONF. Below is a brief description of the surgical repair process:

 General anesthesia: The dog is put under general anesthesia to ensure they are pain-free and still during the operation.

Local anesthesia: A nerve block is given to help prevent pain and lasts for up to three days.

Debridement: The surgeon will clean the area and remove any damaged or dislodged tissue surrounding the fistula.

Flap Technique: A local flap is made and rotated to enclose the Fistula. This flap is usually made from oral mucosa or adjacent tissues. It helps the Fistula heal and seals the gap between the oral cavity and the nasal cavity.

Suturing: The flap is carefully stitched to create a seal that stops the oral cavity from communicating with the nasal cavity.

Recovery: After the operation, the patient may require a few days of soft food and may be given antibiotics and pain meds.

While surgical repair is the most definitive method for treating an oronasal fistula, the procedure’s success can sometimes depend on factors such as the fistula’s location and size, as well as the surgeon’s skill and experience.  It’s essential to consult with a veterinary dental specialist if your regular vet isn’t comfortable with the procedure.

Repaired ONF


Prevention of Oronasal Fistulas

Prevention of oronasal fistulas involves maintaining good oral hygiene and promptly addressing any oral health issues. Regular dental check-ups and cleanings can help prevent advanced periodontal disease, a leading cause of ONFs. If your dog suffers from dental trauma, seek veterinary care immediately to minimize the risk of fistula formation. Additionally, proper technique and care during tooth extractions can prevent complications that might lead to oronasal fistulas. By being proactive in your dog’s dental care, you can reduce the likelihood of this painful condition.



An oronasal fistula in a dog can be distressing for both the pet and the owner. Additionally, they can cause a variety of symptoms that impair quality of life. However, these fistulas can be successfully healed if discovered and treated early. This allows dogs to resume their normal activities without pain. Consult your veterinarian if you suspect your dog has an oronasal fistula. Your pet’s chances of a positive outcome increase the faster the problem is resolved.


Kipp J. Wingo, DVM

Diplomate, American Veterinary Dental College.

Tags: oronasal fistula, dog dental health, veterinary dentist, dog oral health, periodontal disease, oral trauma, dog dental surgery, canine dental issues, veterinary dental care, board-certified vet dentist.