Osteochondritis Dissecans in Australian Thoroughbreds: Incidence and Metabonomic Analysis

RAMOS, MEGHAN; RALSTON, SARAH L.; THOMAS, DONALD S.; PELCZER, ISTVÁN; HOIJEMBERG, PABLO ARIEL; RICHARDS, NERIDA

Simposio; Australasian Equine Science Symposium 2014; 2014

Introduction: Osteochondritis Dissecans (OCD) is common problem in many breeds of horses, including Thoroughbreds. Genetic predisposition to OCD is well established in some breeds of horses, such as Standardbreds, Swedish Warmbloods, and Hanoverians, with significantly higher incidence in some sire lines (Ralston et al, 2011). Due to a similar incidence of OCD in Thoroughbred and Standardbred populations (25-30%) it is hypothesized that there is a heritable predisposition for OCD in Thoroughbreds. OCD maybe be inherited as a polygenetic trait that causes distinct changes in an affected horse?s metabolic profile. Metabonomic analyses using 1H Nuclear Magnetic Resonance (NMR) Spectroscopy of serum have revealed a specific metabolic profile associated with the Development of OCD lesions in Standardbreds (Ralston et al, 2011), giving insight to the underlying metabolic defects. The hypotheses were that metabonomic analyses of serum from OCD and non-OCD yearling Thoroughbred horses would reveal distinct metabolic differences, and that there would be a higher incidence of OCD within certain sire lines. Methods: A total of 375 Thoroughbred yearlings on 13 farms in the Hunter Valley, NSW Australia were evaluated radiographically (hocks, stifles, carpi and fetlocks) by local veterinarians. Detailed reports of dietary history and radiographic results were given to Dr. Richards. There were 5 rations that differed between farms. The identities of the horses and farms were not disclosed to the other authors but were randomly assigned letter/number identification codes. Blood samples were obtained by venipuncture from over 300 yearlings in the sample and serum samples were submitted to Dr. Thomas for 1H NMR analyses. The NMR spectral acquisitions were done on an 800 MHz NMR instrument (Bruker-Biospin). Spectral processing was done by the first author using Mnova (Mestrelab Research. Samples (n=220) from the offspring of 13 stallions who had at least 10 progeny were selected for in depth metabonomic analysis. Many of the farms used the same stallions so offspring of a given stallion were often found on multiple farms. The subset contained 46 OCD and 174 non-OCD horses. Binary data on presence/absence of OCD were evaluated using Analysis of Variance factoring the effects of sire, feed and farm (Statistix 13, Statistix, Tallahassee, Florida). When significance of P