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Also Known As

Sinus infection


The sinuses in a horse are  a cavity in the vone of that skull that communicates with the nostrils and contains air. In a horse, the paranasal sinuses connect with the nasal cavity and are lined by a mucous membrane similar to that in a human nose.

Primary sinusitis is the result of an upper respiratory tract infection that involves the paranasal sinuses in the horse's head. It may involve all sinus cavities or may be confined to one sinus.

Horses are primarily nasal breathers and any problem with the paranasal sinuses can lead to chronic nasal discharge along with distortion of the face. Because the horse must breathe in large quantities of air at proper temperatures and humidity if he is to perform athletic activities, treating equine sinusitis is an urgent matter


  • Nasal discharge, usually unilateral, becoming purulent or bloody
  • Halitosis
  • Facial deformity with a pushed-out appearance over sinus area
  • Discharge from eyes
  • Difficulty chewing food
  • Labored breathing
  • Shaking of head
  • Exercise intolerance


The cause of sinusitis is usually an infectious disease of the upper respiratory tract. Dental disease, cysts, tumors, and trauma to the head and respiratory system also can lead to infection affecting the sinus cavities and causing sinusitis. In some cases, fungal infections that spread into the head and neck areas result in sinusitis. .


Good horse management, including prompt attention to any evidence of infections, problems with teeth, nasal discharge, injury to the head, or signs of cysts or tumors will help prevent sinusitis in most cases.

Prevention of all cases of sinusitis is unrealistic, but adequate attention to general horse health, keeping the environment as clean as possible, and evaluating each horse's health routinely will minimize the seriousness of the condition.


Treatment of primary cases of sinusitis first requires making a definitive diagnosis based on examination of a fluid sample that is cultured for aerobic and anaerobic bacteria and fungi.

If any plant or feed particles are found during the cytological examination, a diseased tooth is likely the problem, or the horse may have an oral-nasal fistula. If halitosis is present, X-rays of the head will determine if the teeth are diseased.

Antibiotic treatment is suggested by most veterinarians based on results of the fluid culture, in conjunction with flushing of the sinus cavity daily for a few days.

Steam inhalation, the administration of medication to thin any discharge and aid in drainage, and light exercise will help the horse return to normal health.

Secondary sinusitis treatment is based on what is causing the problem. In the case of a diseased tooth, the tooth must be removed.

If the sinusitis is the result of cysts, tumors, or injury to the head, these problems must be diagnosed and dealt with before progress can be made in treating the sinusitis. A veterinarian can determine the best course of action.

Once the mucous membranes that line the sinus cavities become infected, the infection can affect the bones of the sinus, making it more difficult to treat the disease.

In some cases, where the disease has affected the sinuses, mucous membranes, and the bone structure, complete recovery will take time and effort, and it is possible that the horse may never fully recover from the infection.

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EquiMed Staff

EquiMed staff writers team up to provide articles that require periodic updates based on evolving methods of equine healthcare. Compendia articles, core healthcare topics and more are written and updated as a group effort. Our review process includes an important veterinarian review, helping to assure the content is consistent with the latest understanding from a medical professional.