Sinus Disease in Horses by a Vet – 2025 Guide to Chronic Nasal Discharge, Tooth Root Infections & Sinus Surgery 🐴🦷

By Dr Duncan Houston, BVSc

Introduction

Persistent nasal discharge is one of the more frustrating problems in equine veterinary care—and sinus disease is often the hidden cause. In 2025, veterinarians continue to diagnose sinus infections, dental-root related infections, cysts, and hematomas as major culprits when a horse has one-sided nasal discharge that does not resolve with antibiotics. Treatment often requires surgical intervention to drain or remove the source of infection or obstruction.

Understanding the Equine Sinus Anatomy 🧠

• Horses have 7 pairs of paranasal sinuses
• These include the frontal, maxillary, dorsal, and ventral conchal sinuses
• These spaces are air-filled cavities in the skull, connected to the nasal passages
• Drainage can be impaired by infection, masses, cysts, or tooth root abscesses

When to Suspect Sinus Disease 🧪

Key Signs:

• Persistent or recurrent nasal discharge
• Discharge is often one-sided (unilateral)
• May be purulent (pus), foul-smelling, or bloody
• Facial swelling or bony deformity
• Bad odor from the mouth or nose
• Reluctance to eat or chew on one side

Common Causes of Equine Sinus Disease 🦠

1. Bacterial Sinusitis

• Often secondary to upper respiratory infections
• May resolve initially with antibiotics but then return
• Often requires surgical sinus flushing to clear infection

2. Tooth Root Infections

• Cheek teeth in the upper jaw have roots that extend into sinus cavities
• Dental abscesses can infect the sinus, causing foul nasal discharge
• Requires dental extraction—often under general anesthesia

3. Sinus Cysts

• Fluid-filled sacs within the sinus cavity
• Not infected, but may cause drainage, facial swelling, and breathing difficulty
• Treatment is surgical removal via bone flap or sinusotomy

4. Ethmoidal Hematomas

• Benign masses arising from the ethmoid region near the sinuses
• Cause intermittent bleeding from the nose
• Treated by laser therapy or formalin injection

5. Tumors or Cancer

• Rare, but must be ruled out with persistent symptoms
• Diagnosis via biopsy, endoscopy, and advanced imaging

Diagnostic Tools for Sinus Disease 🛠️

• Endoscopy: Nasal scope to inspect sinus openings and rule out guttural pouch disease
• Skull Radiographs or CT Scan: Identify fluid levels, bone changes, or masses
• Oral Exam: Check for dental disease or feed packing in cheek teeth

Treatment of Sinus Disease 💊🔧

Flushing the Sinus

• Requires creation of a bone hole or surgical flap into sinus cavity
• Flushes remove pus and debris; repeated daily for several days

Tooth Extraction

• Required for dental infections
• Can be performed via oral extraction or sinus approach

Cyst or Tumor Removal

• Requires full access to the sinus cavity
• Surgical dissection and curettage needed for cystic structures

Case Example: Gelding with Foul One-Sided Discharge

1. 10-year-old gelding presented with thick, green, smelly discharge from left nostril
2. No response to oral antibiotics after 2 weeks
3. Endoscopy and x-ray revealed maxillary sinus infection
4. Oral exam showed decay in left upper 3rd molar
5. Horse underwent sinusotomy, dental extraction, and 5 days of flushing
6. Discharge resolved within 10 days post-op

FAQs About Sinus Disease in Horses

Q: My horse has had discharge for a month—is that normal?

A: No. If nasal discharge lasts more than 2 weeks, especially from one nostril, your horse needs evaluation for sinus disease.

Q: Can antibiotics alone treat sinus infections?

A: Rarely. Sinuses are poorly drained and often need to be flushed surgically for effective resolution.

Q: Is sinus surgery risky?

A: It’s routine and well-tolerated in most horses. Complications are uncommon with proper care and technique.

Conclusion

Sinus disease is a common yet complex cause of chronic nasal discharge in horses. In 2025, the most effective treatments still involve diagnosing the underlying cause—whether it's bacterial infection, dental disease, or cyst—and applying surgical techniques to drain, extract, or remove the problem. Long-term discharge from one nostril should never be ignored. Early intervention leads to faster recovery and less stress for horse and owner alike.

Need help diagnosing your horse’s nasal or facial issue? Visit AskAVet.com or download our app 📱 to consult Dr Duncan Houston for sinus and dental evaluations. 🩺🐴