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While a bacterial infection is the most common reason why sinusitis occurs, other primary conditions can cause the sinuses to become filled with mucus and swell. Premolar and molar tooth roots can become diseased, a cyst or tumor could cause a blockage, or a condition such as Cushing’s disease could predispose a horse to sinus problems. While treatment for many causes of sinusitis through medical and surgical therapies is effective, it should be sought as soon as possible to prevent a progression into more serious conditions, such as tissue necrosis.
The sinuses are air filled cavities inside the head, face and parts of the mouth. Sinusitis occurs when those cavities become inflamed or infected. Seen in all ages of horses, sinusitis is most commonly caused by an upper respiratory infection. Symptoms of a foul smelling nasal discharge, trouble breathing, and facial swelling can be a signal that your horse needs medical attention.
Sinusitis can be classified as primary or secondary. Either type of sinusitis can be either acute or chronic.
This type of sinusitis results from a bacterial infection of the upper respiratory tract. This causes a buildup of mucus or pus within the sinus cavities. It generally affects all the paranasal cavities, but can affect only the ventral conchal sinus cavity.
This type is caused by another primary condition, such as dental disease, bone fractures, granulomatous lesions, sinus cyst, or a neoplasia, and accounts for half of all cases of sinusitis. More often, infections and problems with the last four cheek teeth cause secondary sinusitis, since these teeth are located within the maxillary sinuses.
Causes of sinusitis in horses include:
After a complete physical and oral examination, your veterinarian will perform tests to be able to correctly diagnose sinusitis, and to identify the cause. These tests can include an endoscopic exam to look for the origin of the discharge, X-rays and CT scans to identify fractures, sinus cysts, neoplasia, or dental disease, and percussion of the sinuses. To further diagnose a bacterial or fungal infection, or a neoplasia, bacterial cultures are tested from biopsies, aspiration, or a sinoscopy.
The goal of the treatment of sinusitis is to remove the discharge in order to restore your horse’s normal drainage system. This is done with medication, irrigation, and surgery if needed. Treatment that is delayed or ineffective can lead to more serious conditions, such as osteomyelitis, abscesses, and advanced necrosis.
While acute cases of primary sinusitis can clear spontaneously, antibiotics can be prescribed early on to help. Anti-inflammatories are prescribed to reduce swelling from the sinusitis or from any surgical procedures. Antimicrobials and antifungal medications may also be needed.
Chronic cases will need lavage and drainage, which can be performed with a sinus irrigation of sterile saline. Trephination is performed while the horse is standing under sedation and anesthesia, and uses an antibiotic solution to flush out the sinuses. An endoscopy can be used to assess the progress. Sinusotomy can also take place on a standing horse, and involves placing a catheter to assist in drainage. Drainage procedures may need to be repeated several times before the condition is resolved.
Additional surgery may be needed to remove excess mucus, or to perform surgical debridement in cases of osteomyelitis or abscess. Secondary sinusitis may need surgery to remove diseased teeth or resolve dental conditions, to repair fractures, to remove cysts, lesions, or neoplasia, or to remove or debulk a fungal infection.
Your horse may need to be hospitalized for 3 to 7 days, depending on how invasive the treatment is. Your veterinarian will want to schedule an exam to evaluate the success of treatment.
The rate of recovery depends on the cause and treatment of your horse’s sinusitis. Many cases can be completely resolved with treatments, which may involve supportive therapies or medications at home. Exercise may also be recommended to aid in mucus expulsion. A future veterinary visit is often scheduled to assess your horse’s progress.
Causes of secondary sinusitis may have more guarded results, as lesions can reoccur, and neoplasias are often difficult to completely remove. Your veterinarian will discuss your horse’s recovery based on his particular condition.
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My horse was diagnosed with sinusitis Jan 18. He was treated with 2 rounds of antibiotics then 2 different drugs and a final round of antibiotics. These treatments failed so our vet referred us to a clinic to have lavage done. Here, they xrayed and thought he had a fractured tooth. Referred to equine dentist. She thoroughly examined teeth and couldn't see a problem in tooth. Referred to University College of Dublin Vet Hospital where dental and sinus specialist would see him. CT showed chronic left sided sinusitis, slight query over tooth but not enoigh evidence to warrant extraction. 4 days of trephination and seemed ok. A few months later the problem returned. Back to UCD to find tooth needed extracted. Followed by 10 days of trephination. 2 months on and nasal discharge is still there. It had improved to a certain degree but seems to have plateaued. If anything seemed to he slowly getting worse. Next step could be back to UCD for frontal bone flap but need to give it a little more time to see if it self resolves
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