Characterization of the Laminitic Hoof Transcriptome in the Horse

Laminitis, inflammation of the sensitive structures of the hoof, is a major concern for many hooved livestock species. The etiology of the disease is complex and not well-characterized. In the horse, laminitis is the second leading cause of both lameness and euthanasia. Current research of the transcriptomic changes in the hoof have utilized qPCR or microarray methods, which require prior knowledge of gene structures. Whole transcriptome sequencing provides a unique opportunity to access differential gene expression across the genome despite incomplete annotation, as well as to identify novel expressed loci in the equine hoof tissue. Whole transcriptome sequencing of sagittal lamellar sections from one control and two affected cases was performed to evaluate the potential benefits of the technology to laminitis research. The control animal presented with no evidence of lameness upon veterinary examination and no gross pathological evidence at necropsy. The selected cases represented two different disease states of laminitis, with one acute case (secondary to enterocolitis) and one chronic case (repeat episodes related to Equine Metabolic Syndrome). An initial differential expression analysis comparing gene expression in each case relative to the control separately revealed 54 significant loci in common. In addition, there were 122 and 107 differentially expressed loci unique to the acute and chronic samples respectively. Analysis of affected pathways and overrepresented gene ontologies is currently on-going. Sequencing of the hoof transcriptome represents a powerful potential to examine the transcriptional affects of laminitis and may aid in the identification of targets for novel treatments.