Sinusitis is an infection of the lining in the frontal and/or maxillary sinus of the horse, caused by bad teeth, tumours, Streptococcus bacteria or fungal infections. It is a relatively uncommon disease, although there is a high incidence of respiratory disease affecting stabled horses. Sinusitis can affect horses of any age; however, tooth infections are generally the cause of sinusitis in older horses.
Generally, with sinusitis a thick, creamy nasal discharge is present. The normal hollow sound heard when tapping the sinus cavity becomes dull, especially when the sinus is full of pus. According to Dr. Barak Amram, writing in the Vet Moves website, the eye on the infected side might have a discharge, and swelling below the eye is possible. Typically, if the source of the infection is a tooth, other symptoms such as, fetid odour, painful chewing and blood in the discharge are present.
The overall attitude of the horse is an indicator of the pain he is experiencing in his head from the pressure of the fluid in his sinus cavity. Through X-rays of the head and a complete physical examination, the veterinarian can determine whether the sinuses are filled with fluid and pus.
Early cases of sinusitis respond positively to a course of antibiotic and monolithic drugs such as sputolosin. Turning the horse out to pasture as much as possible also aids in healing, as the head-down eating posture facilitates drainage from the affected sinus.
In cases of secondary sinusitis, horses who do not respond to medical treatments undergo a surgical procedure to make holes into the sinus, a technique known as trephining. Another effective procedure involves performing continuous lavage of the sinus with an antiseptic solution for several days until the infection has cleared up. Large amounts of fluid flushed in and out of the sinus help dilute bacteria and debris. If the initial cause of the sinus infection is a bad tooth, a veterinary specialist can remove the tooth.
Regular examinations by a veterinarian to detect dental impactions, infection, disease in teeth sockets, and periodontal disease is one preventive measure for secondary sinusitis.