Scanning electron microscopy and fungal culture of hoof horn from horses suffering from onychomycosis.

This study investigates the presence and effects of fungal infections in the hoof horns of horses showing symptoms of a disease known as equine onychomycosis. The researchers cultured fungi from the hoof samples and used scanning electron microscopy to examine the structure of the affected hooves, highlighting marked differences between infected and healthy hoof material.

Sampling and Cultural Examination

• The researchers collected hoof samples from eight horses that exhibited clinical signs of onychomycosis in at least one of their hooves.
• The typical hoof abnormalities were sand cracks, white line disease, brittleness around nail holes, parakeratosis (a skin disorder), and bruising.
• For examination, the scientists transferred the samples onto Sabouraud Dextrose Agar and Dermatophyte Test Agar, both of which are mediums used for the favorable growth of fungi.
• The cultures were kept at room temperature for 30 days in order to observe fungal growth. After 30 days, the fungi types were identified by their structural features and the appearance of their spore-producing structures (conidia) under the microscope.

Scanning Electron Microscopy Observation

• Further investigation of the samples was conducted using Scanning Electron Microscopy (SEM). SEM allows detailed observation of the surface structures on a microscopic level and reveals any structural changes that might have occurred due to the disease.
• The hoof samples were kept at -80°C until they were ready for electron microscopy examination.

Findings

• The results of the fungal growth showed that all eight horses were infected with keratinophilic fungi, which is capable of using keratin as a nutrient source and thus can cause disease in keratinous tissues such as hooves.
• Other keratin-digesting fungi, namely Trichophyton spp. and Scopulariopsis brevicaulis, were also detected in six out of the eight horses’ samples.
• SEM imaging displayed significant alteration in the hoof structure in infected samples comparing to healthy hoof samples, such as change in the tubular structure of the hoof wall, disruption of horny layers, superficial decay of cornified cells, and the evident presence of fungal elements.
• However, the hoof samples without dermatophyte or Scopulariopsis infection showed similarity with healthy hoof horn, which suggests that these infections are likely responsible for the observed structural damage.

It’s critical to note that the implications of this research could aid in the improved detection and treatment of equine onychomycosis, enhancing our understanding of fungal infections in horses more broadly.