A horse with sinus disease may show any of the following signs: a one-sided nasal discharge of thick white or yellow pus or mucus, blood, or a distinctive unpleasant odor from one nostril.
The horse has several sinus cavities, with the maxillary sinuses being the largest. The maxillary sinuses are divided by a thin wall into two parts, called rostral and caudal. The roots of some of the upper molars lay in these sinuses and are only separated from the sinuses by a thin sheet of bone. These teeth can develop an infection that travels into the sinuses, which is called secondary sinusitis. Secondary sinusitis means a sinus infection caused by another problem, such as a tooth infection, periodontal disease, cyst, or mass. The most common cause of secondary sinusitis is a dental infection. Primary sinusitis is caused by a bacterial or fungal infection without a secondary cause.
An oral examination, endoscopy and radiographs will help to confirm a secondary dental sinusitis. To treat it, a veterinarian will extract the problem tooth and sometimes flush or clean out the sinuses. In these cases, the infection cannot be resolved until the affected tooth has been extracted. Antibiotics may temporarily clear up the sinus infection, but because bacteria can hide inside the tooth despite long courses of antibiotics, once the antibiotics are discontinued, the sinus infection will return. This type of sinusitis can be complicated to treat, however, regular dental exams by a veterinarian can often catch infected teeth or periodontal disease before they cause a sinusitis.
As discussed in our last blog post, Cushings disease suppresses the horse’s immune system and increases the risk for periodontal disease and sinus infections. Untreated dental problems in Cushinoid patients can be life threatening, which is why routine oral examinations by your veterinarian are important, especially in older horses.
As always, if you notice something abnormal going on with your horse, don’t hesitate to call your veterinarian. It is always better to be proactive about your horse’s health!