Pathogenesis of OCD: how does this translate to management of the clinical case?

Introduction

Osteochondrosis (OC) is common in many breeds of horses. Osteochondrosis is a decisively invalidating disease only in relatively exceptional cases where lesions are so extensive that no repair is possible. Nevertheless, it has a strong impact on equine welfare and on the economics of the equine industry because of the loss of potential breeding stock and the decrease in value of affected horses. Research in recent years has shed more light on the pathogenesis and provided more insight in this very complex disease, which may help us in reducing the impact of the disorder.

Current concepts in the pathogenesis of OC

The greatest recent breakthrough on the mechanisms of the pathogenesis at tissue level of OC is the evidence that damage to the micro-vasculature plays a pivotal role in the early pathogenesis of OC. The transition in the arterial source of vessels in the cartilage canals of the growth cartilage from perichondrial to vessels crossing the ossification front represents a vulnerable period for the occurrence of damage [1]. With the early pathogenetic mechanism now well established, the underlying aetiology is more complex. Many factors of both genetic and environmental character are known to be of importance.
Linkage and association analyses and genome-wide association studies identified regions of the genome that were associated with some phenotypic manifestation of OC on not less than 22 of the 33 chromosomes of the horse [2], showing the complex genetic background of the disease which is also confirmed by the large differences in heritability (h2 ) per joint [3].
Growth rate, no matter whether driven by genetics or a high nutritional intake is positively correlated with the occurrence of OC [4]. Exercise is a double-edged sword. There are associations between both the prevalence and the severity of osteochondrotic lesions with irregular access to pasture, as well as with keeping animals in very large plots [5,6]. Stabling overnight and pasture access during the daytime and rough and slippery grazing grounds are risk factors as well [7].  […]