More Than a Runny Nose

When a horse presents with a foul-smelling discharge from just one nostril, it’s a strong clue that there may be an underlying dental issue. In this case, a 26 year old mare appeared comfortable overall—bright, eating well, and acting normal—but a persistent foul odor and one-sided discharge prompted further investigation. A comprehensive dental exam was performed and multiple abnormalities were found including periodontal disease, multiple ulcers on the roof of the mouth, and gingival hyperplasia.  The most significant finding, however, was a fractured molar. This fracture had pulp exposure, which means the sensitive parts of the tooth like nerves and blood vessels are exposed. This can lead to to discomfort, infection, and decay of the tooth.

To complete the work up, radiographs were taken of the skull and teeth. X-rays showed a fluid line present in the maxillary sinus, indicating the cavity was infected and had fluid and pus inside. It also showed significant disease and tooth root loss of the fractured molar.

Why this happens

The roots of the upper cheek teeth sit very close to the maxillary sinuses. When a tooth becomes fractured, decayed, or infected, bacteria can easily travel from the tooth root into the sinus, leading to chronic infection and discharge. As long as the diseased tooth remains, sinus infections often persist despite antibiotic treatment. Treatment focuses on eliminating the source of the infection and clearing out the sinuses.

Treatment and Hospitalization

The first step in treatment was to remove the fractured tooth that was causing the infection. Using sedation, local anesthesia, and specialized dental tools, the tooth was extracted. Because of her extensive periodontal and dental disease, a second tooth was removed as well to prevent future infections.

Following the removal of the tooth, she was kept at the Shoreline clinic to manage the sinus infection. A needle was placed through the thin facial bones in the face into the sinus cavity. This allowed us to flush warm fluids through the sinus and out the nose.  A flush was performed daily for a week until her flushes no longer had discharge. During this time, she was also given oral antibiotics twice daily.

Discharge

After a week of care, this patient was doing wonderfully. Her nasal discharge had resolved, the extraction sites healed beautifully, and she continued to eat well and be bright. At home, she finished out a course of antibiotics, but continued to do well and required no other supportive care. She was rechecked again 4 weeks after her procedure to ensure healing was complete. Due to now missing teeth and her abnormal dentition, she will require more frequent dental exams and equilibration (floating).

The Takeaway

Persistent, foul-smelling discharge from one nostril is rarely a simple issue. Dental evaluation is a critical part of diagnosing and treating these cases early and effectively. If you notice ongoing nasal discharge or odor in your horse, we are always happy to help determine the cause and discuss next steps.