Equine Oral Health Resources

Horses have several sinus cavities, including the ventral conchal and maxillary sinuses, which are located near the upper molars. The roots of these molars are only separated from the sinuses by a thin layer of bone, making them vulnerable to infection. When a tooth becomes infected, the infection can spread into the sinus cavity—this is known as secondary sinusitis. Secondary sinusitis is typically caused by an underlying dental issue, such as a tooth infection, periodontal disease, cyst, or mass.

In contrast, primary sinusitis is caused directly by a bacterial or fungal infection, without any underlying dental problem.

A horse with sinus disease may develop one-sided nasal discharge of thick white or yellow pus or mucus. Blood may also be present. You will also likely notice a distinctive unpleasant odor coming from one nostril.

If left untreated, a dental infection can progress into a serious sinus condition. Over time, the sinuses can fill with fluid, pus, and even food, causing significant discomfort. While antibiotics may temporarily clear up the infection, they often fail to completely eradicate it. This is because bacteria can hide within the infected tooth, and once antibiotics are discontinued, the sinus infection will return.

An oral examination, endoscopy and radiographs will help to confirm a secondary dental sinusitis. To fully resolve secondary sinusitis, the infected tooth must be extracted—antibiotics alone are not enough.

Regular dental exams by a veterinarian can often catch infected teeth or periodontal disease before they cause sinusitis.

In the CT image below, the sinuses appear black, indicating they are filled with air. However, on the left side of the image, you can see a tooth with an apical infection and a surrounding gray area, indicating that the sinus is filled with material. When an infection progresses this far, sinus surgery may be needed to remove the inspissated (thickened) material in addition to extracting the infected tooth and providing antimicrobial treatment.

This case involved a mare presenting with a six-week history of left-sided malodorous nasal discharge. Despite antibiotic treatment, the symptoms persisted. Upon oral examination, the mare was found to have an enlarged lymph node on the left side of her head, along with nasal discharge. Additionally, she had a complicated crown-root fracture and caries (decay) of the 209 tooth.

Diagnosis and Imaging
Radiographs revealed a tooth root infection in the 209 tooth, which had led to secondary sinusitis.

Challenges with Cheek Teeth Extractions
Cheek teeth extractions can be particularly challenging due to dental interlock—the teeth are so tightly packed together that it becomes difficult to maneuver them within the tooth socket (alveolus). This issue is often worse in young horses with larger teeth or in cases where the teeth are fractured, causing adjacent teeth to shift into the space of the fractured tooth.

To overcome these challenges, a partial coronectomy technique was used. This procedure involves removing a sliver of the mesial (front) or distal (back) portion of the tooth to create more space for extraction, allowing the tooth to be moved more easily within the socket.

The Partial Coronectomy Procedure
Given that the crown of the 209 tooth was already fragile due to the previous fracture, the decision was made to perform a partial coronectomy. The procedure involved carefully removing a sliver from the distal aspect of the tooth to provide more room to manipulate the tooth during extraction.

By doing this, the tooth was successfully extracted without causing further fracture to the remaining crown.

Post-Operative Care
Post-operative radiographs confirmed that the entire tooth was successfully extracted. The alveolus (tooth socket) was packed with dental impression material to aid in healing and was removed approximately two weeks later. The mare continued antibiotic treatment for another two weeks to ensure the sinus infection resolved.

With proper treatment, the sinus infection was cleared, and the socket healed effectively.

This case involved a 28-year-old Warmblood gelding with a more than one-year history of left-sided malodorous nasal discharge. Despite several rounds of antibiotic treatment and a partial extraction of tooth 211 by a lay person, his nasal discharge persisted. Upon oral examination, the horse showed faint malodor from the left nostril and had an enlarged lymph node on the left side of his head. There was no active nasal discharge at the time of the exam. His 209 tooth was worn down to the gum line due to his age, and his 210 tooth was fractured with fragments of the 211 still present.

Diagnosis and Imaging
Radiographs revealed:

• Periodontal disease and tooth infection in the 209 and 210 teeth
• Retained fragments of the 211 tooth
• Evidence of a sinus infection, likely secondary to the tooth infections

Challenges and Procedure: Tooth Extraction via Sectioning
The patient was sedated, and the left side of his head was numbed using a local nerve block. The 209 tooth was so worn down from age that there wasn't enough crown left to grasp with forceps. Normally, a tooth with no crown to hold onto would require a sinus surgery, which is highly invasive with a risk of complications. However, in this case, we opted to section the 209 tooth into two halves using a specialized burr. This technique allowed us to extract each half individually, avoiding the need for more invasive surgery.

Additionally, the 210 tooth was also extracted, as it was fractured. The retained roots of the 211 were left in place.

Addressing the Sinus Infection
Since horses with secondary sinus infections due to dental disease often have two separate infections (the tooth infection and the sinus infection), the first step was to extract the infected teeth. While antibiotics may resolve the tooth infection, sinus infections, especially chronic ones, require additional treatment.

In this case, sinus surgery was necessary. The sinus infection had persisted for so long that the mucus in the sinuses had become thick, similar to cream cheese, preventing it from draining properly through the small sinus passageways. Antibiotics alone could not penetrate or clear this thickened material.

To address this, a local surgeon performed a sinoscopy, a minimally invasive procedure involving a small, quarter-sized hole made in the sinus. A flexible endoscope (a small camera) was inserted to inspect the sinuses. Specialized instruments were used to flush and remove the infected material from the sinuses.

Outcome
After the tooth extractions and the sinus surgery, the nasal discharge resolved, and the horse recovered. The horse’s sinus infection was successfully treated, and his condition improved significantly, marking a positive outcome for this case.