Histopathological findings in equine sinonasal disorders.

This study looks at the histological examination of biopsy samples from 79 horses diagnosed with various sinonasal disorders. Different features such as type and integrity of epithelial, inflammatory cellular response, fibroplasia, and presence of pathogens were observed. The findings uncovered chronic inflammatory changes similar to human sinusitis and some pathological characteristics with unclear cause-and-effect relationships.

Methodology and Sample Population

• The biopsy samples were collected from a total of 79 horses suffering from different predominant sinonasal diseases. This included 27 horses with primary sinusitis, 10 with secondary dental sinusitis, 19 with sinus cysts, 11 with progressive ethmoid haematomata (PEH), 4 with false nostril epidermal inclusion cysts, 4 with sinonasal polyps, 3 with sinonasal mycosis, and 2 control animals with no known disorders.

Observations and Findings

• The authors made several observations based on qualities such as epithelial type and integrity, cellular inflammatory response, fibroplasia, and the presence of potential pathogens in the tissue samples.
• Most horses with sinonasal diseases exhibited chronic inflammatory changes including mucosal thickening, ulceration, and significant fibroplasia, phenomena also observed in human chronic sinusitis.
• Although bacteria were variably present on the sinusitis mucosae, their role in causing the sinusitis is unclear.
• Some cases showed irreversible changes, including fibroplasia. This may explain why some horses with sinus diseases respond poorly or show delay in response to treatment.

Comparisons and Contrasts

• Sinus cysts in the sample horses had histological similarities to human mucocoeles.
• The analysis of progressive ethmoid haematomata revealed discernible recent and older haemorrhage, an observation also made for sinus cysts and, to some degree, chronic sinusitis cases.
• Despite the presence of haemorrhage in both sinus cysts and PEH, no evidence supporting a common cause between these two disorders was found.

Implications of the Study

• This study broadens the understanding of the histopathological characteristics of equine sinonasal disorders and provides a basis for comparison with similar human conditions.
• The findings can help direct future research on the aetiology of these diseases, as well as improving diagnostic accuracy and the treatment strategies for different equine sinonasal disorders.