Large equine CT study links diagnosis to sinonasal disease outcomes

CURRENT FULL VERSION: A major new Equine Veterinary Journal paper is putting hard numbers behind a familiar equine practice challenge: chronic sinonasal disease is common, heterogeneous, and its outcome depends heavily on the underlying diagnosis. In the study, researchers analyzed 1,600 horses with CT-confirmed sinonasal disease and found that dental sinusitis caused by apical infection was the leading diagnosis, representing 43.3% of cases. They also reported that horses with sinonasal tumors and progressive ethmoid hematoma had significantly worse cure rates than horses with primary sinusitis, while primary, dental, and mycotic sinusitis had the highest complete cure rates overall. (madbarn.com)

The paper sits within a broader four-study EVJ package from the same international dataset, giving the findings more clinical depth than a single retrospective review usually can. According to the associated Dryad dataset, the cases came from 21 contributors across 19 equine clinics in the UK, continental Europe, and the U.S. The authors used CT-confirmed inclusion criteria, which is notable because the investigators said in an EVJ podcast discussion that many sinus cases are now better understood as “sinonasal” disease due to frequent involvement of the nasal conchal bullae, especially since standing CT and more targeted endoscopy became more widely used. (datadryad.org)

That framing also helps explain why this series may mark a shift from older equine sinus literature. Earlier work by Dixon and colleagues, including a 200-case EVJ study and a 277-case treatment follow-up, established the value of endoscopy, sinoscopy, and radiography, but those studies were built in an earlier imaging era. More recent reviews have emphasized that clinical examination is still the starting point, yet CT is often required to define the underlying cause, especially when dental, cystic, traumatic, fungal, or neoplastic disease can all present with overlapping signs such as unilateral nasal discharge. (beva.onlinelibrary.wiley.com)

The new paper’s topline finding, that dental sinusitis dominates the caseload, matters because it aligns diagnosis with a potentially more actionable treatment pathway. The companion historical and clinical paper shows just how chronic and pre-worked many of these horses were before referral: median disease duration was 17.9 weeks, 12.6% had already undergone maxillary cheek tooth extraction, 11.8% sinoscopy, 5.2% nasofrontal sinus osteotomy, and 3.6% maxillary sinus osteotomy. At presentation, nasal airflow was obstructed in 14.9% of cases and facial swelling was present in 26.9%; on nasal endoscopy, 65.8% had exudate at the sinonasal ostium and 44.6% had middle meatus abnormalities including inspissated exudate, sequestra, and sinonasal fistulae. In the companion CT paper from the same 1,600-horse cohort, cases with apically infected teeth had a higher likelihood of cure, while caudal sinusitis and bone hyperostosis were linked to lower cure rates. In the treatment paper, based on 1,299 horses with CT-confirmed disease, sinoscopic debridement with maxillary septal bulla fenestration was performed in 47.3% of horses, sinoscopic lavage in 54.7%, nasofrontal sinusotomy in 24.9%, and maxillary sinusotomy in 7.2%. Sinoscopic treatment and oral extraction were associated with higher likelihood of cure, while nasofrontal sinusotomy was associated with poorer outcomes, although the authors note that more difficult cases may have been overrepresented in the osteotomy group. Taken together, the series suggests that the “what is it?” question may be as important as the “how bad is it?” question when advising a pet parent or referring veterinarian on prognosis. (madbarn.com)

The authors and EVJ’s podcast host also highlighted the scale of the work as part of its significance. In the podcast episode published September 2, 2026, the researchers described the four papers as a “mammoth” effort and said the multicenter design was intended to overcome the low case volumes even referral hospitals may see individually. They also noted that all included horses had disease confirmed by CT, with retrospective review of clinical records, prior workups, treatments, and outcomes. That doesn’t eliminate the usual limitations of retrospective research, but it does strengthen confidence that the diagnostic categories were more consistently defined than in older series based mainly on clinical impressions or radiography. (podscan.fm)

Why it matters: For veterinary professionals, especially equine practitioners balancing first-opinion work with referral decision-making, the study sharpens three practical points. First, chronic nasal discharge should prompt a broader sinonasal mindset, not a narrow sinusitis label, because nasal cavity structures may be part of the disease process. Second, CT-supported etiologic diagnosis appears to improve prognostic clarity, with dental disease generally carrying a better outlook than tumors or progressive ethmoid hematoma. Third, timing still matters: in the companion historical and clinical paper, older age, longer disease duration, prior nasofrontal sinusotomy, and the presence of facial swelling or bilateral nasal discharge at presentation were all associated with lower odds of complete cure. The treatment analysis adds that oral extraction was associated with increased likelihood of cure, while nasofrontal osteotomy and moderate-to-severe bone hyperostosis were associated with lower cure odds. (podscan.fm)

For hospitals with CT access, the series may also support more standardized case pathways around imaging, dentistry, sinoscopy, and referral communication. For practices without CT, it gives stronger evidence for when persistent or atypical cases should move up the diagnostic ladder. And because the dataset spans Europe and the U.S., the findings may feel more generalizable than single-center reports, even if referral bias still likely enriched the population for more complex disease. That last point is an inference from the study design and the authors’ own description that many cases were referred in for CT and treatment. (datadryad.org)

What to watch: The next step is whether this unusually large dataset changes frontline workups, earlier referral patterns, and uptake of less invasive sinoscopic approaches as the EVJ special focus issue formally publishes on October 5, 2026, and the papers begin to circulate more widely in continuing education and case discussions. The treatment paper gives that question some immediate relevance: sinoscopic approaches were common and linked with better outcomes, whereas horses needing nasofrontal osteotomy were less likely to achieve cure, whether because of procedure choice, case selection, or both. (podscan.fm)