Identification and validation of risk loci for osteochondrosis in standardbreds.

BACKGROUND: Osteochondrosis (OC), simply defined as a failure of endochondral ossification, is a complex disease with both genetic and environmental risk factors that is commonly diagnosed in young horses, as well as other domestic species. Although up to 50 % of the risk for developing OC is reportedly inherited, specific genes and alleles underlying risk are thus far completely unknown. Regions of the genome identified as associated with OC vary across studies in different populations of horses. In this study, we used a cohort of Standardbred horses from the U.S. (n = 182) specifically selected for a shared early environment (to reduce confounding factors) to identify regions of the genome associated with tarsal OC. Subsequently, putative risk variants within these regions were evaluated in both the discovery population and an independently sampled validation population of Norwegian Standardbreds (n = 139) with tarsal OC. RESULTS: After genome-wide association analysis of imputed data with information from >200,000 single nucleotide polymorphisms, two regions on equine chromosome 14 were associated with OC in the discovery cohort. Variant discovery in these and 30 additional regions of interest (including 11 from other published studies) was performed via whole-genome sequencing. 240 putative risk variants from 10 chromosomes were subsequently genotyped in both the discovery and validation cohorts. After correction for population structure, gait (trot or pace) and sex, the variants most highly associated with OC status in both populations were located within the chromosome 14 regions of association. CONCLUSIONS: The association of putative risk alleles from within the same regions with disease status in two independent populations of Standardbreds suggest that these are true risk loci in this breed, although population-specific risk factors may still exist. Evaluation of these loci in other populations will help determine if they are specific to the Standardbred breed, or to tarsal OC or are universal risk loci for OC. Further work is needed to identify the specific variants underlying OC risk within these loci. This is the first step towards the long-term goal of constructing a genetic risk model for OC that allows for genetic testing and quantification of risk in individuals.

Rutgers Young Horse Teaching and Research Program: undergraduate student outcomes.

Equine teaching and research programs are popular but expensive components of most land grant universities. External funding for equine research, however, is limited and restricts undergraduate research opportunities that enhance student learning. In 1999, a novel undergraduate teaching and research program was initiated at Rutgers University, New Brunswick, NJ. A unique aspect of this program was the use of young horses generally considered "at risk" and in need of rescue but of relatively low value. The media interest in such horses was utilized to advantage to obtain funding for the program. The use of horses from pregnant mare urine (PMU) ranches and Bureau of Land Management (BLM) mustangs held the risks of attracting negative publicity, potential of injury while training previously unhandled young horses, and uncertainty regarding re-sale value; however, none of these concerns were realized. For 12 years the Young Horse Teaching and Research Program received extensive positive press and provided invaluable learning opportunities for students. Over 500 students, at least 80 of which were minorities, participated in not only horse management and training but also research, event planning, public outreach, fund-raising, and website development. Public and industry support provided program sustainability with only basic University infrastructural support despite severe economic downturns. Student research projects generated 25 research abstracts presented at national and international meetings and 14 honors theses. Over 100 students went on to veterinary school or other higher education programs, and more than 100 others pursued equine- or science-related careers. Laudatory popular press articles were published in a wide variety of breed/discipline journals and in local and regional newspapers each year. Taking the risk of using "at risk" horses yielded positive outcomes for all, especially the undergraduate students.

Rutgers Young Horse Teaching and Research Program: sustainability of taking a risk with "at risk" horses.

In 1999, the Young Horse Teaching and Research Program (YHTRP) was initiated at Rutgers University. The unique aspect of the program was using horses generally considered "at risk" and in need of rescue, but of relatively low value. The risks of using horses from pregnant mare urine (PMU) ranches and Bureau of Land Management (BLM) mustangs were high, but, ultimately, unrealized. No students or staff members were seriously injured over the course of the next 12 yr, and the horses were sold annually as highly desirable potential athletes or pleasure horses, usually at a profit. The use of "at risk" horses generated a significant amount of positive media attention and attracted substantial funding in the form of donations and sponsorships, averaging over $60,000 (USD)per year. Despite economic downturns, public and industry support provided sustainability for the program with only basic University infrastructural support. Taking the risk of using "at risk" horses paid off, with positive outcomes for all.

Evidence-based equine nutrition.

One of the most difficult problems in equine nutrition research is often the lack of objective and clinically relevant end points. Nevertheless, this article attempts to present the best evidence (or lack thereof) for some of the most common clinical questions pertaining to such topics as the evaluation of glucose and insulin tolerance and factors that may confound results, dietary management of horses prone to laminitis and rhabdomyolysis, nutritional prevention of gastric ulcers and developmental orthopedic disease, the efficacy of commonly used herbal products, and feeding geriatric horses.

Beyond blood sugar: the potential of NMR-based metabonomics for type 2 human diabetes, and the horse as a possible model.

Metabonomic analysis is a powerful tool for identifying and characterizing metabolic disorders, for example type 2 diabetes and the metabolic syndrome. Nuclear magnetic resonance (NMR) spectroscopy is an essential tool for such analysis, with special benefits. The review assesses the current status and potential of NMR-based metabonomics of type 2 diabetes. The horse is proposed as a possible model for studying this condition and disease. Some examples are shown of horse blood analyses by NMR.

Insulin and glucose regulation.

Abnormally high or low blood glucose and insulin concentrations after standardized glucose tolerance tests can reflect disorders such as pituitary dysfunction, polysaccharide storage myopathies, and other clinical disorders. Glucose and insulin responses, however, are modified by the diet to which the animal has adapted, time since it was last fed, and what it was fed. Body fat (obesity), fitness level, physiologic status, and stress also alter glucose and insulin metabolism. Therefore, it is important to consider these factors when evaluating glucose and insulin tests, especially if only one sample it taken. This article describes the factors affecting glucose and insulin metabolism in horses and how they might influence the interpretation of standardized tests of glucose tolerance.