Historical, clinical and nasal endoscopic findings in 1600 cases of equine sinonasal disease and associations with case outcome.

Overview

• This study analyzed clinical data from 1600 horses with sinonasal disease to identify factors in their medical history, clinical signs, and nasal endoscopy findings that influence treatment outcomes.

Background and Objective

• Sinonasal disease in horses involves inflammation or infection of the nasal and sinus cavities, which can lead to breathing issues and other complications.
• Prior to this study, no large-scale research had comprehensively described the patient characteristics (signalment), treatments before referral, and clinical or endoscopic findings related to this disease.
• The objective was to explore connections between case outcomes (such as complete cure vs. ongoing disease) and various factors including horse demographics, previous treatments, and clinical or endoscopic observations.

Methods

• Retrospective case series using medical records from 19 equine hospitals.
• Inclusion criteria: Each case had confirmed sinonasal disease and underwent CT imaging for diagnosis.
• Data extracted included:
  • Signalment: Age and other demographics of the horses.
  • Pre-referral treatments: Antibiotics and surgical interventions before cases were referred.
  • Clinical signs at presentation, such as nasal airflow obstruction and facial swelling.
  • Nasal endoscopy findings, such as exudate presence and abnormalities in nasal passages.
  • Case outcome data obtained from follow-up via records and contact with owners or vets.
• Statistical analysis: Multivariable logistic regression to find variables significantly associated with outcomes, analyzing 650 cases with complete data.

Key Findings

• Total cases studied: 1600 (1457 unilateral, 143 bilateral sinonasal disease).
• Most cases were chronic, with a median duration of nearly 18 weeks before referral.
• Common pre-referral antibiotics included:
  • Potentiated sulphonamides
  • Doxycycline
  • Procaine penicillin
• Pre-referral surgical treatments included:
  • Extraction of maxillary cheek teeth (234 teeth in 201 horses, or 12.6% of cases)
  • Sinoscopy (endoscopic sinus examination, 11.8%)
  • Nasofrontal sinus osteotomy (5.2%)
  • Maxillary sinus osteotomy (3.6%)
• At referral presentation:
  • Nasal airflow obstruction was present in 14.9% of cases.
  • Facial swelling occurred in 26.9% of cases.
  • Nasal endoscopy revealed:
    • Exudate at the sinonasal ostium in 65.8% cases.
    • Abnormalities in the middle meatus (part of the nasal cavity) including thickened exudate, bone sequestra (dead bone fragments), and sinonasal fistulae in 44.6%.

Factors Associated with Treatment Outcome

• Using multivariable logistic regression on 650 cases, several factors significantly associated with a reduced chance of complete cure were identified:
  • Age over 12 years at presentation (Odds Ratio [OR] 0.53). Older horses had about half the odds of complete cure compared to younger horses.
  • Sinonasal disease duration longer than 8 weeks (OR 0.63), indicating chronicity decreased cure likelihood.
  • Having undergone nasofrontal sinusotomy before referral (OR 0.36). This prior surgery was linked to a substantially lower chance of cure after referral.
  • Presence of facial swelling or bilateral nasal discharge at referral presentation (OR 0.33), indicating more severe or widespread disease.

Conclusions and Clinical Implications

• Equine sinonasal disease is typically chronic by the time of referral, often involving complicated clinical and endoscopic findings.
• Older horses and those with longer disease duration have poorer prognosis, suggesting early diagnosis and intervention are important.
• Prior surgical interventions, especially nasofrontal sinusotomy, may decrease likelihood of complete recovery post-referral, possibly reflecting more severe or refractory cases.
• Presence of facial swelling and bilateral nasal discharge at presentation indicate more advanced disease and lower chances of cure.
• These findings provide veterinarians with prognostic indicators to help manage expectations and tailor treatment strategies for sinonasal disease in horses.
• Limitations: Retrospective design and incomplete data for some cases may affect generalizability.