Diagnosed causes of sinonasal disease in 1600 horses and associations with clinical signs, computed tomographic findings and case outcome.

Overview

• This study analyzed 1600 horses with sinonasal diseases using computed tomography (CT) to identify the causes, associated clinical signs, CT imaging features, and the outcomes of different conditions.
• It aimed to correlate specific diagnoses with observable symptoms, CT findings, and final treatment success or failure.

Introduction and Purpose

• Sinonasal disorders in horses affect the nasal and sinus cavities and can result from diverse causes such as infections, cysts, tumors, trauma, or fungal infections.
• CT imaging has improved the ability to diagnose these disorders more precisely compared to traditional methods.
• The objective was to explore how specific diagnoses relate to clinical signs and CT images, and how these diagnoses predict case outcomes.

Methods

• A retrospective case series design was used, analyzing data from medical records at 19 equine hospitals.
• All horses included in the study underwent CT imaging to confirm the diagnosis.
• Outcome data was collected from clinical records, follow-up communications with clients, and referring veterinarians.
• Statistical analysis using logistic regression assessed associations between diagnoses, clinical and CT features, and outcomes.

Results: Diagnoses and Frequency

• A total of 1600 cases were categorized by diagnosis, with dental sinusitis due to apical infection being the most common cause (43.3% or 693 cases).
• Other diagnoses included:
  • Primary sinusitis (20.6%, 329 cases)
  • Sinus cysts (11.1%, 178 cases)
  • Progressive ethmoid haematoma (PEH) (6.3%, 100 cases)
  • Traumatic sinonasal disease (5.6%, 90 cases)
  • Sinonasal neoplasia or suspected neoplasia (5.4%, 86 cases)
  • Other non-neoplastic growths (0.6%, 11 cases)
  • Mycotic infections (4.1%, 65 cases)
  • Other less frequent causes including pneumocele, oro-nasal fistulae, sinus mucocele, and facial suture infection

Results: Clinical Sign Associations

• Facial swelling was more frequently seen in cases with sinonasal cysts, tumors, traumatic injuries, and fungal infections compared to other causes.
• Nasal malodour was most commonly associated with dental sinusitis, likely due to infection-related odors.
• Nasal airflow obstruction was prominent in cases of sinus cysts, PEH, and tumors, indicating mass effect or blockage.
• Empyema, or pus accumulation in nasal conchal bullae, was seen less in cysts, PEH, trauma, and tumors, indicating these conditions are less purulent.
• More severe bone thickening (hyperostosis) on CT scans correlated with sinus cysts and tumors, reflecting chronic or aggressive disease processes.

Results: Outcome Analysis

• Sinonasal tumors had a significantly lower likelihood of cure (Odds Ratio [OR] 0.03, CI 0.01-0.07) compared to primary sinusitis, indicating poor prognosis.
• PEH also had reduced chances of full recovery (OR 0.23, CI 0.12-0.43) relative to primary sinusitis.
• Primary sinusitis showed better treatment success rates, serving as a reference for favorable outcomes.

Conclusions and Implications

• Equine sinonasal disease includes many different underlying causes, each affecting clinical presentation and treatment outcomes differently.
• CT imaging is valuable in differentiating these causes based on anatomical and pathological features like hyperostosis, cyst formation, and tumor presence.
• Facial swelling, nasal odor, and airflow obstruction vary with the disease cause and provide clinical clues for diagnosis.
• Prognosis depends heavily on diagnosis; tumors and PEH have poorer outcomes than primary sinusitis.
• The study acknowledges limitations such as its retrospective nature and lack of histology in some cases, which may affect diagnostic accuracy.
• Overall, this research supports the use of CT for better diagnosis and management planning in equine sinonasal diseases, highlighting the need for tailored treatment based on specific disease types.