Onychomycosis in white line disease in horses: pathology, mycology and clinical features.

The research article focuses on investigating the occurrence, causes, and impacts of onychomycosis, a fungal infection, in horses suffering from white line disease. The study identifies specific fungi associated with this condition and analyses their effects on the hooves of the observed horses.

Study Design and Sample Collection

• The researchers examined 100 hooves from 51 Thoroughbred horses suffering from white line disease, a condition affecting the hoof wall.
• Out of these, 15 hooves from 13 horses also had severe hoof wall fissures, deep cracks, or splits in the hoof wall, presenting more serious complications.
• The team performed both histopathology (study of changes in tissues caused by disease) and cultures to identify the fungi involved. The diagnosis of onychomycosis was confirmed histologically, meaning it was visually confirmed under a microscope.

Findings and Results

• They diagnosed ten samples as being affected by onychomycosis, seven of which showed severe inner hoof wall fissures.
• They managed to isolate Scedosporium apiospermum or its variant form, Pseudallescheria boydii, a type of soil fungus, predominant in the fissure cavities, the terminal horn of the white line, and the terminal horn-like laminae of the metaplastic white line-like tissue.

Implications and Conclusions

• This study concludes that onychomycosis frequently triggers or exacerbates white line disease.
• Deterioration of the submural condition (condition under the hoof wall) often accompanies this.
• Scedosporium apiospermum was identified as the main fungus associated with onychomycosis in this study.
• The most susceptible area to infection was found to be the terminal horn of the hypertrophied white line and/or the terminal horn-like laminae of the metaplastic white line-like tissue.