Abstract
Craniofacial sutures are fibrous connections between the flat bones in the skull, allowing a small amount of movement to absorb strain and load as long as they are patent. In the present study, we examined the histological appearance of facial suture lines in horses of different ages. The internasal, nasofrontal and maxillolacrimal sutures were macroscopically identified and extracted from the skulls of six horses aged 1 day (two horses), 5 days, 2, 6 and 9 years and prepared into histological samples. The suture lines were then examined for width, form, cell density and morphology, vascularisation and morphology of the surrounding tissue and compared based on the age of the horse. Although macroscopically the sutures became difficult to identify in the 6‐ and 9‐year‐old horses, histologically they were clearly visible in all samples, indicating that the sutures were patent and consisted of connective tissue in all analysed horses. The sutures became subjectively narrower with lower cell density in older horses as compared to young horses, and there was a noticeable maturation from woven to cancellous bone surrounding the sutures. Vascular structures were present in all sutures regardless of age or location. In conclusion, this study raises awareness of the histological suture conformation in neonatal and adult horses and their persistence into adulthood. A better understanding of the histological structure of facial sutures and their continued patency into adulthood can aide in the interpretation of radiographs and computed tomography images of the head and in improving treatment methods and outcomes for horses affected with suture exostosis. In addition, if biopsies are taken, clinicians will have a basis on which to determine which cells are related to the disease process and which are normally occurring.
Geitzenauer, Lindsay