Computed tomographic findings in 1600 cases of equine sinonasal disease and associations with case outcome.

Overview

• This study analyzed CT scans of 1600 horses with sinonasal disease to identify common imaging findings and investigated how those findings relate to treatment outcomes.
• It specifically examined the impact of sinus infections, bone changes, and dental infections on the chances of recovery.

Purpose and Background

• Sinonasal disease in horses affects the sinuses and nasal passages, commonly leading to sinusitis.
• Computed tomography (CT) provides detailed images useful for diagnosing sinus disease and related conditions.
• No large-scale study had previously described typical CT findings in equine sinonasal disease and how these findings correlate with outcomes.
• This research aimed to fill that gap by retrospectively analyzing a large number of cases.

Methods

• Retrospective case series using data from 1600 horses referred for sinonasal disease at 19 equine hospitals.
• All included horses underwent CT imaging for diagnosis.
• Clinical records were reviewed to gather information on CT findings and case outcomes (whether the horse was cured or not).
• Outcome data was supplemented by contacting clients and referring veterinarians when necessary.
• Multivariable logistic regression was used to identify CT findings at presentation that were statistically associated with the likelihood of cure.

Key CT Findings

• Most horses (1457/1600) had unilateral sinusitis, with the remaining 143 showing bilateral disease.
• The rostral maxillary sinuses were most often affected (86.1% of cases), followed by the ventral conchal sinuses (74.8%).
• Approximately 21-39% of cases showed fluid or distortion in the ventral nasal conchal bullae (NCB), and 16-28% in the dorsal NCB.
• Inflammatory thickening of sinus bones (hyperostosis) was present in:
  • 35.5% mild cases
  • 19.8% moderate cases
  • 8.7% severe cases
  • Absent in 36.1% of cases
• A total of 659 infected teeth without fractures and 200 fractured apically infected teeth were identified, highlighting dental infection as a common problem.
• Interestingly, scans of “normal” opposite sinuses in 100 horses showed 114 cheek teeth with apical infections, indicating subclinical dental infections may exist.

Associations with Case Outcome

• Statistical analysis included 674 cases with complete data.
• Horses with dental sinusitis (apically infected teeth, fractured or non-fractured):
  • Had a higher likelihood of cure (Odds Ratios ~2.0), suggesting these types of infections respond well to treatment.
• Cases with caudal group sinusitis had a significantly lower likelihood of cure (OR ~0.48), meaning infections in rear sinuses are harder to treat effectively.
• Moderate or severe bone hyperostosis also correlated with a lower chance of cure (OR ~0.53), indicating that chronic or severe inflammation of sinus bones compromises recovery.

Conclusions

• Dental infections, specifically involving cheek teeth, do not always cause clinical sinusitis even when evident on CT.
• Bone hyperostosis and involvement of caudal sinus regions predict poorer treatment outcomes, likely reflecting more advanced or difficult disease.
• Cases of sinusitis caused by apical tooth infections have better odds of successful treatment, potentially because these causes are more straightforward to address surgically or medically.
• The study was limited by incomplete data for some cases and its retrospective nature.
• These findings help veterinarians better understand CT imaging features linked to prognosis in equine sinonasal disease and may guide treatment planning.