Open Connection Between the Mouth and Nose in Dogs (Oronasal Fistula)

  • Occurrence: rarer
  • Location of disease: Head/Neck
Author: Dr. med. vet. Gisa Löwe | Last modified: 02.06.2026
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When to visit the vet?

Non-urgent see a veterinarian within 2–3 days

?

If the condition worsens / symptoms persist, consult a veterinarian.

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Definition

An oronasal fistula in dogs is an abnormal connection between the oral cavity and the nasal cavity, often caused by a defect in the hard palate. This fistula allows the unintended passage / transit of fluids and food from the oral cavity into the nasal cavity, which can lead to various health problems.

The most important facts at a glance

Oronasal fistulas in dogs are connections between the oral and nasal cavities, often caused by a defect in the hard palate. Causes of these fistulas are often tooth extractions, especially of the upper canine teeth, as their roots lie close to the floor of the nasal cavity. Improper extractions can lead to perforations. Traumas, infections, Tumors, or congenital defects can also cause fistulas. Symptoms include nasal discharge, Sneezing, and visible holes in the gums. Diagnosis is made through clinical examination and imaging such as X-ray or CT, sometimes supplemented by endoscopy and bacteriological tests.

Treatment usually requires surgery, in which the fistula is covered with tissue from the surrounding mucosa. Multiple procedures may be necessary, depending on the size of the fistula and the dog’s health. After surgery, antibiotics and a soft diet are important to promote healing. The prognosis is usually good with timely and correct treatment. Prevention includes good oral hygiene, regular dental check-ups, and careful tooth extractions by experienced veterinarians. Traumas should be avoided, as should chewing on hard objects. Early detection and treatment of infections or Tumors can reduce the risk of fistula formation.

Causes

Oronasal fistulas often develop due to a defect in the hard palate, which separates the oral cavity from the nasal cavity. The hard palate consists of bone covered by a thin mucosal layer. This structure can be damaged by various causes, leading to the formation of a fistula.

One of the most common causes of an oronasal fistula in dogs is tooth extraction, especially when the upper canine teeth need to be removed. The roots of these teeth are located close to the floor of the nasal cavity, and improper extraction can lead to a perforation. Traumas such as blows or falls can also damage the palate and cause a fistula to form.

In addition, infections or Tumors in the area of the oral cavity or palate can contribute to weakening of the tissue structure and thus to the formation of a fistula. Congenital defects of the palate, which are more common in certain dog breeds, can also play a role.

Symptoms

Rare symptoms:

Dogs with an oronasal fistula often show various symptoms that indicate an unintended exchange of substances between the oral and nasal cavities. A common sign is food particles or fluids coming out of the dog’s nose, especially after eating or drinking.

Affected dogs may also develop Sneezing, nasal discharge, or chronic nasal inflammation. Another common symptom is Cough or Respiratory distress, which can be caused by food or fluids entering the airways.

In some cases, Weight loss or refusal to eat may also occur, as eating can be uncomfortable or painful for the dog. Bad breath and Inflammatory conditions in the mouth are also possible symptoms.

Diagnosis

Diagnosis of an oronasal fistula is usually made through a thorough clinical examination of the dog. The veterinarian will carefully inspect the oral cavity for visible defects or abnormalities in the palate area. A fistula can often be identified through direct visual inspection.

In addition, imaging procedures such as X-rays or computed tomography (CT) can be used to determine the extent of the fistula and possible underlying causes such as dental problems or Tumors.

In some cases, endoscopy of the nasal cavity may be required to assess the severity of the fistula and rule out other possible causes of the symptoms. A bacteriological examination of the nasal discharge may also be performed to identify secondary infections.

Therapy

Treating an oronasal fistula in dogs usually requires surgery to close the connection between the oral and nasal cavities. The surgeon will clean the affected tissue and cover the fistula with a tissue flap taken from the surrounding mucosa or from other parts of the oral cavity.

In some cases, it may be necessary to perform the procedure in several stages, especially if the fistula is large or complex. The success of the operation depends on various factors, including the size of the fistula and the dog’s overall health.

After surgery, careful follow-up care is important to support healing and prevent complications. This includes administering antibiotics to prevent infections and providing a soft or liquid diet to protect the palate during the healing phase.

Prognosis and follow-up care

The prognosis for dogs with an oronasal fistula depends on various factors, including the cause of the fistula, the extent of tissue damage, and the effectiveness of treatment. In many cases, surgical correction can lead to successful healing, especially if the fistula is detected and treated early.

Timely treatment and correct surgical technique are crucial for a positive prognosis. Complications such as infections or recurrence of the fistula can impair healing, but are less common with proper aftercare.

Dogs that are successfully treated can usually lead a normal and healthy life, although regular veterinary check-ups are important to ensure that no new problems arise.

Prevention

Prevention of oronasal fistulas in dogs focuses primarily on avoiding risk factors that can lead to fistula formation. Careful oral hygiene and regular dental check-ups can help detect and treat dental problems before they lead to a fistula.

For tooth extractions, especially of the upper canine teeth, it is important that the procedure is performed by an experienced veterinarian to minimize the risk of complications. The veterinarian should be well informed about the anatomy of the jaw and use appropriate techniques to avoid damage to the palate.

In addition, avoiding traumas to the mouth and head area can help preserve the integrity of the palate. Owners should ensure their dogs do not chew on hard or sharp objects and minimize potential hazards in their environment.

Early detection and treatment of infections or Tumors in the oral cavity can also help reduce the risk of developing an oronasal fistula.

Frequently asked questions (FAQs)

1. What is an oronasal fistula?
An oronasal fistula is a pathological connection between the oral and nasal cavities. Through this opening, food, fluid and saliva enter the nose. Typical signs are sneezing after eating, unilateral nasal discharge and chronic inflammation of the nasal mucosa.
2. What are the causes?
Most oronasal fistulas develop as a consequence of severe periodontitis, particularly at the maxillary canine. The bone plate between tooth root and nasal cavity is very thin there and breaks down with advanced bone loss. Other causes include trauma, tumors, surgical complications and rarely congenital clefts.
3. Which breeds are particularly affected?
Small and toy dogs with narrow jaws — Dachshund, Pomeranian, Maltese, Yorkshire Terrier and Toy Poodle — are at considerably higher risk because of the narrow maxilla and frequent periodontitis. Dolichocephalic breeds with narrow muzzles are also more prone.
4. What symptoms point to it?
Characteristic features are chronic, often unilateral purulent or bloody nasal discharge, sneezing after eating, food particles in nasal secretions and sometimes airway noises. Foul oral odor is usually present because the underlying periodontitis is typically marked.
5. How is the diagnosis made?
Diagnosis is made during dental examination under anesthesia. Careful probing of the affected periodontal pocket reveals the connection to the nasal cavity. Dental radiographs or CT show the extent of bone lysis and aid surgical planning.
6. How is an oronasal fistula treated?
The treatment of choice is surgical closure. The affected tooth is extracted, the fistula is excised and the defect is closed tension-free with a mucosal flap (single- or double-flap technique). Antibiotic therapy supports healing, especially with concurrent rhinitis.
7. Can the fistula heal on its own?
No. Once formed, the connection does not close spontaneously, as the constant flow of air and fluids prevents healing. Without surgery, chronic rhinitis, secondary infections and significant impairment of quality of life develop.
8. What is the prognosis after surgery?
With careful surgery and tension-free suturing, success rates are about 80 to 90 percent. Recurrences are most often caused by tension on the suture, infection or premature chewing of hard food. Recurrence requires a second surgery.
9. What postoperative measures are necessary?
After surgery, the dog is fed soft food for several weeks, must avoid hard toys and should not be subjected to strain on the head. Mouth rinses with chlorhexidine support healing. Follow-ups are scheduled after 10 to 14 days.
10. How can it be prevented?
Regular dental care and annual dental examinations with professional cleanings are the most important preventive measures. Periodontitis must not be overlooked, especially in small dogs. Early extraction of severely affected canine teeth can prevent fistula formation.