16/09/2026
It might seem an unlikely connection, but some of your horse’s upper teeth sit close to the sinuses, the air-filled spaces inside their head. An infection around a tooth’s root can sometimes spread into those spaces.
A study published last week in the BEVA Equine Veterinary Journal looked at CT scans from 1,600 cases of horses with nasal and sinus disease, gathered from 19 equine hospitals.
Researchers found infections around the roots of both broken and unbroken teeth. They also found that a tooth infection doesn’t always lead to a sinus infection.
So, what should you look out for?
According to the American College of Veterinary Surgeons, signs of sinus problems can include:
• A runny nose on just one side, sometimes with a bad smell, pus or blood.
• Swelling on one side of the face.
• A watery eye.
• Unusual sounds when breathing in.
A runny nose doesn’t automatically mean a tooth problem. Sinus trouble can have several causes, and your vet may need to look beyond what’s visible from the outside to work out what’s going on.
If nasal discharge keeps coming back or isn’t clearing up, especially from just one nostril, contact your vet. Swelling, blood or changes in breathing also need veterinary attention.
Knowing what’s normal for your horse, and noticing when something changes, is something every owner can do.
