Horse Species Symposium
By: Meghan Thorndyke
Dr. Jim Heird kicked off the 2019 ASAS horse species symposium with the topic of horses and the horse industry, Texas and beyond. During his talk, he mentioned the size and scope of the equine industry and the impact in the United States and Texas. Dr. Heird proceeded to address the issues in the equine industry. He mentioned the decline in participation which could be an effect of the recession in 2008 as the horse industry is controlled by discretionary money. Declining breed registration trends since 2008 are hurting the equine industry as breed associations make revenues through registration, transfers, memberships, and sponsorships. This idea results in a decline in income to the breed associations which result in a domino effect to decreased advertising, membership, support to events in shows and cause a decline in sponsorships and therefore a decrease in employee number and level of customer service. Youth participation is also struggling as a result of competition form other youth activities such as sports, the cost, and engaging actives. Dr. Heird brought to light the idea of unwanted horses, public without livestock experience, and welfare issues and growing influence of animal welfare groups. The idea of most individuals being three generations away from animal agriculture has caused an increase in anthropomorphism in youth and Dr. Heird did mention the need for training in young horse leaders to help ensure the longevity of the equine industry.
Dr. Molly McCue a DVM, Ph.D. discussed using genomics to better understanding muscle function and dysfunction. Her major focuses were genomic and unraveling recurrent exertional rhabdomyolysis (RER) as well as genomics and understanding energy deficient in horses with GYS1 mutation (PSSM1). The objectives of Dr. McCues RER study were to identify candidate genes and function mutations for RER susceptibility and to predict individuals at risk for RER before symptoms using genome -association studies (GWAS), Random forest analysis, and biological candidate gene technologies. When combining the three methodologies 16 million WGS variants were able to be narrowed down to 7,778 variants with 210 predicted functional effects and ~32,000 variants used for predictive assay and identify likely functional alleles. Overall the implication of stratification of disease risk in RER was able to find risk from near or lower than average risk to extreme risk over the life time absolute risk for RER and the animal welfare consequences associated with each risk level. In term of her studies on PSSM1, the hypothesis that PSSM1 horses develop rhabdomyolysis during submaximal exercises due to altered expression of genes involved in skeletal muscle energy metabolism and clinical improvement resulting from consistent daily exercise is due to the restoration of more normal gene expression patterns in the metabolic pathway. Dr. McCue’s group was curious as to why these horses tie up if they can make and utilize glycogen and found decreased rations of cytosolic ATP:ADP, activated AMP deaminase and increase levels of muscle IMP.
Attempts to improve equine athletic performance via hypoxia-inducing techniques from Dr. Brian D Nielsen from Michigan State University was next. He focused around blood doping, the ability to better oxygen carrying capacity in the blood. He mentioned traditional means such as spinning down blood and pumping red blood cells back into the body as well as EPO. His main focus though for this talk was to determine if Equine blood doping was plausible first he addressed the issue of cobalt in the industry and its ability for blood cell formation (hematopoiesis) by hypoxia inducing characteristics which results in a similar in function to EPO and results in an elevated rate of erythropoiesis. He found that the splenic contraction in horses results in RBC release and render the possible effects of Cobalt seeming useless. Dr. Nielsens group then became interested in answering if high altitude chambers can mimic hypoxia environments in horses as a form of high-altitude training. The objectives of his studies were to evaluate if horses could be acclimated to high altitude chambers (HAC), performance in standardize exercise test (SET), and racing performance. In conclusion, the group found that horses could be adapted to HAC and improved in race performance were not noted in preliminary work.
Dr. Sarah H White wrapped up the horse symposium with the topic of using skeletal muscle mitochondrial profiles to create individual management programs for elite performance horses. Dr. Whites research addresses energy availability and training stating that we know immunomodulary effects, muscle protein synthesis, regulation autophagy, enhanced antioxidant status, and mitochondrial biogenesis are involved in training of horses but is interested in understanding the exact response elicited. During the course of her research, she found that training did not improve mitochondrial biogenesis, but in fact, the mitochondria are getting larger making the animals more efficient through citrate synthase (CS) activity responsible for mitochondrial volume density and cytochrome c oxidase (CCO) activity responsible for mitochondrial function. Through this research, she is now interested in determining if there are different management strategies for different individual horses and if it was possible to predict which horses will succeed and make it through a training regimen at a young age in order to improve animal welfare in the industry.