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Diagnosis
Conditions or ailments that are the cause of a problem that you see - your observation.

Your vet may diagnose

Orbital Cellulitis

Synonyms: Infection Around or Behind the Eye

Summary

Summary
Cellulitis is an infection of tissues and tissue planes. Orbital cellulitis is a bacterial infection of the soft tissues surrounding the eyeball — the fat, muscles, and connective tissue that fill the eye socket (orbit). It causes rapid, painful swelling around the eye, often making the eye appear to bulge forward. The horse usually has a fever and shows significant pain, especially when trying to open its mouth or chew. The area is extremely sensitive to touch and horses guard the area carefully.

This condition develops when bacteria invade the orbital tissues, usually from a wound near the eye, a tooth root infection, sinus infection, or sometimes a foreign body like a wood splinter or plant material. Orbital cellulitis is a veterinary emergency. Without treatment, the infection can damage the eye itself, form an abscess behind the eye, or spread to surrounding structures.

The good news is that most horses respond well to aggressive antibiotic and anti-inflammatory treatment, especially when caught early. Your vet needs to see this horse today — the faster treatment starts, the better the outcome.

When It Happens
Orbital cellulitis typically develops rapidly — often within 24-48 hours. You may notice sudden swelling around one eye that gets worse quickly. It can follow a wound near the eye, but sometimes there is no obvious injury. It can happen at any age and any time of year. Horses with dental disease or sinus problems may be more prone because infection can spread from the teeth or sinuses into the orbit.


YOUR ROLE

• Call your vet immediately — this is a same-day emergency.
• Take your horse’s temperature. Fever supports infection.
• Do NOT try to open the swollen eye or apply pressure.
• Put a fly mask on if tolerated — protects from flies and debris.
• Note whether the horse can chew and eat normally. Pain opening the mouth is a hallmark.
• Look for discharge, abnormal color, or third eyelid covering part of eye.
• Take photos from multiple angles and send directly to your vet.
• Keep horse in a clean, fly-free area until the vet arrives.
• If you have bute or banamine, ask your vet if you should give a dose.

my vet's role

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OTHER DIAGNOSES CONSIDERED

Other conditions or ailments that might also need to be ruled out by a vet.

Very Common
Less Common
Rare
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PROGNOSIS AND RELEVANT FACTORS

The prognosis is good if there is not a foreign body, fracture or injury to the eye. The prognosis depends on these factors. The prognosis for orbital cellulitis is generally good when caught early and treated aggressively with antibiotics and anti-inflammatories. Most horses show significant improvement within 3-4 days of starting treatment. However, relapses can occur, especially if an underlying cause (tooth root infection, sinus disease, foreign body) is not identified and addressed. In complicated cases, treatment may take longer and may require surgery. Rarely, severe or neglected cases can result in permanent damage to the eye or loss of vision.

my role

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I might observe

You might make these observations when a horse has this condition.

Very Common
Less Common
Rare
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Questions To Ask Your Vet:
  • Could this be from a tooth root problem or sinus infection, or is it from a wound?

  • Does the eye itself appear damaged, or is it just the tissues around it?

  • Will my horse need imaging (X-rays, ultrasound, or CT) to find the cause?

  • How long will treatment take, and what is the risk of relapse?

  • Is there a chance the eye could be permanently affected?

  • Should I be watching for signs that this is getting worse or coming back?
Prevention

There is no way to completely prevent orbital cellulitis, but you can reduce the risk. Keep your horse’s environment free of sharp objects and protruding hazards that could cause eye-area wounds. Use fly masks, especially in fly season, to protect the eyes from insects and debris. Stay current on dental care — routine dental exams help catch tooth root problems early, before they can spread to the orbit. If your horse sustains a wound near the eye, have your vet evaluate it promptly rather than waiting to see if it heals on its own.
Breeds at Risk
All breeds equally. No breed predisposition is documented for orbital cellulitis.

further reading & resources

Author: Doug Thal DVM Dipl. ABVP