Comparative microcomputed tomographic structural analysis of the trabecular and cortical bone architecture of radius and ulna in toy dog breeds.

Radius and ulna fractures can be detected in dogs with an incidence of 18.0% and occur more frequently in toy breeds with increased complication rates. The reasons for the predisposition and the increased complication rate of antebrachial fractures in toy breeds are not yet fully understood. The aim of this study was to research the associated mechanisms by investigating the trabecular structure parameters (BV/TV (%), Tb.N (mm), Tb.Th (mm), Tb.Sp (mm), Conn. D (mm), DA) and the cortical bone density (Mean Density (mg HA/ccm)) for toy breeds and small dogs of other breeds using microcomputed tomography and to identify the differences between both groups. A total of 70 forearms, originating from toy breeds (n = 36) and small dogs of other breeds (n = 34) were evaluated by microcomputed tomography. The results of this study showed a lower bone volume fraction (BV/TV), more (Tb.N) but thinner trabeculae (Tb.Th) with greater separation (Tb.Sp) and decreased diaphyseal cortical density (Mean Density) in toy breed dogs. This could thus contribute to the increased risk of antebrachial fractures in toy breeds. Within the group of toy breeds inhomogeneous results were observed, whereby the values of the Chihuahuas deviated. This breed had significantly thinner trabeculae (Tb.Th) with a greater trabecular separation (Tb.Sp), lower bone volume fraction (BV/TV) and significantly lower diaphyseal cortical density (Mean Density). These parameters could therefore indicate an increased antebrachial fracture and complication risk, especially in Chihuahuas.