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: 09.08.2026
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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 palatal segment. 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 that often result from a defect in the hard palatal segment. Causes of these fistulas are often tooth extractions, especially of the upper canine teeth, as their roots are located 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. The diagnosis is made through clinical examination and imaging techniques such as X-ray or CT, sometimes supplemented by endoscopy and bacteriological examinations.

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 largely good with timely and correct treatment. Prevention includes good oral hygiene, regular dental checkups, 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 the unintended exchange of substances between the oral and nasal cavities. A common sign is the appearance of food particles or fluid from the dog’s nasal cavity, especially after eating or drinking.

Affected dogs may also sneeze, develop 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.

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 promote healing and prevent complications. This includes administering antibiotics for infection prevention as well as 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 / relapse of the fistula can impair healing but are less common with proper follow-up care.

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

The prevention of oronasal fistulas in dogs focuses primarily on avoiding risk factors that can contribute to fistula formation. Careful oral hygiene and regular dental checkups can help detect and treat dental problems early before they lead to fistula formation.

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 versed in 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 that 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.

Outlook on current research

Research on oronasal fistulas today focuses primarily on three goals: better prevention, safer surgical closure, and more reliable healing. An oronasal fistula is a pathological connection between the oral and nasal cavities. It can develop after surgery, injuries, or Inflammatory conditions, as well as with congenital malformations, and affects eating, speaking, and Susceptibility to infection.

An important focus is the refinement of surgical techniques. Tissue flaps that are better vascularized and therefore heal more stably are being investigated. Three-dimensional surgical planning and imaging techniques are also gaining importance because they help to more accurately assess the size, location, and stress on the defect. This allows the procedure to be planned more individually.

A second area of research is regenerative medicine. Here, it is being examined whether biomaterials, collagen matrices, or the body’s own growth factors can support tissue regeneration. In the long term, stem cell-based procedures could also play a role, although these approaches are currently predominantly experimental.

Increasingly important is also the question of which factors promote failure, such as infections, tension in the wound area, poor blood circulation, or underlying diseases. The goal is to identify high-risk patients earlier and better adapt treatment.

Overall, the outlook is cautiously optimistic: research is moving away from standard solutions toward more individualized, biologically supported therapy concepts with better healing prospects.

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 nasal cavity. Typical signs are Sneezing after eating, unilateral nasal discharge, and chronic Rhinitis.
2. What are the causes?
Oronasal fistulas most commonly develop as a result of severe periodontitis, especially at the upper canine tooth. The bony lamella between the tooth root and the nasal cavity is very thin there and breaks through with advanced Bone resorption. Other causes include traumas, Tumors, surgical complications, and more rarely congenital clefts.
3. Which breeds are particularly affected?
Small and toy dogs with narrow jaws such as Dachshunds, Pomeranians, Maltese, Yorkshire Terriers, and Toy Poodles have a significantly increased risk due to the narrowness of the upper jaw and frequent periodontitis. Dolichocephalic breeds with narrow skulls are also at higher risk.
4. What symptoms indicate it?
Characteristic is a chronic, often unilateral purulent or bloody nasal discharge, Sneezing after eating, food particles in the nasal secretion, and occasionally respiratory sounds. A foul mouth odor is also often present, as the underlying periodontitis is usually quite pronounced.
5. How is the diagnosis made?
The diagnosis is made during a dental examination under anesthesia. By carefully probing the affected tooth pocket, the connection to the nasal cavity can be demonstrated. Dental X-ray or CT shows the extent of bone lysis and facilitates surgical planning.
6. How is an oronasal fistula treated?
The therapy of choice is surgical closure. First, the affected tooth is extracted, the fistula is excised, and then closed tension-free with a mucosal flap (single or double flap technique). Antibiotic therapy accompanies healing, especially with existing Rhinitis.
7. Can the fistula heal on its own?
No. Once a connection has formed, it does not close spontaneously, as the constant passage / transit of air and fluid prevents healing. Without surgery, chronic Rhinitis, secondary infections, and significant impairments in quality of life occur.
8. What is the prognosis after surgery?
With careful surgery and tension-free suturing, the success rate is approximately 80 to 90 percent. recurrence / relapse occurs most often due to too much tension on the suture, infections, or premature chewing of hard food. In these cases, a second surgery is required.
9. What postoperative measures are necessary?
After surgery, the dog receives soft food for several weeks, should not chew on hard toys, and should have minimal stress to the head. Mouth rinses with chlorhexidine support wound healing. Follow-up examinations occur after 10 to 14 days.
10. How can it be prevented?
Regular dental care and annual dental checkups with professional cleaning are the most important prevention. Especially in small dogs, signs of periodontitis should not be overlooked. Early extraction of severely damaged canine teeth can prevent the development of a fistula.

Literature

  • Smith, M. M. (2000). Oronasal fistula repair. Clinical Techniques in Small Animal Practice, 15(4), 243–250. https://doi.org/10.1053/svms.2000.21398
  • Sauvé, C. P., MacGee, S. E., Crowder, S. E., & Schultz, L. (2019). Oronasal and oroantral fistulas secondary to periodontal disease: A retrospective study comparing the prevalence within Dachshunds and a control group. Journal of Veterinary Dentistry, 36(4), 236–244. https://doi.org/10.1177/0898756420909657
  • Taney, K. T. K., Smith, M. M., Cummings, N. P., & Lozano, A. J. (2021). Risk factors for failure of hard palate mucoperiosteal flap repair of acquired oronasal communication in dogs: A pilot study. Frontiers in Veterinary Science, 8, Article 762842. https://doi.org/10.3389/fvets.2021.762842
  • Shannon, S. (2022). Surgical repair of acquired oronasal fistulas secondary to periodontal disease in dogs using a flexible bone membrane: A case series. Journal of Veterinary Dentistry, 39(1), 63–70. https://doi.org/10.1177/08987564211067862
  • Lorrain, R. P., & Legendre, L. F. J. (2012). Oronasal fistula repair using auricular cartilage. Journal of Veterinary Dentistry, 29(3), 172–175. https://doi.org/10.1177/089875641202900306
  • Marretta, S. M., & Smith, M. M. (2005). Single mucoperiosteal flap for oronasal fistula repair. Journal of Veterinary Dentistry, 22(3), 200–205. https://doi.org/10.1177/089875640502200301