Breed the Best to the Best

Genomics is a buzz word, even among scientists. The term genomics includes the entire complement of chromosomes, genes, and DNA sequences that make up humans and animals. Technological advances during the last 15 years have led to the entire genome sequencing for humans, mice, cattle, chickens, and dogs. Thousands of bacteria and viruses have been DNA sequenced as well. We know that vertebrates have approximately three billion DNA base pairs and 20,000 genes. However, the 20,000 genes account for only 3% of the DNA bases; we do not know a function for the remaining 97%. The amount of information produced by genomics is immense and has led to a wedding of biology with computer science in a field now called bioinformatics.

What will be the impact of genomics on horse breeding? Since the late 1600s, horse breeders have been renowned as geneticists, starting with the promotion of Thoroughbred race horses by England’s King Charles II. Three hundred years of selection changed the performance and athletic abilities of the Thoroughbred. Even in the shadow of genomics, the adage remains true, "Breed the best to the best and hope for the best." Why? The point is, while genomic studies focus on details of biology, the horse breeder considers the entire breeding program. So what benefits can the horse breeder derive from genomics? The answer is apparent in the large number of diagnostic tests produced from genomics research during the last decade of human medicine. They are akin to radiographs, bacterial cultures, and blood enzyme values, and thus have the potential to help develop better vaccines and therapeutics.

Already, genomics studies have led to development of diagnostic tests for bacteria, viruses, and several hereditary diseases of horses (hyperkalemic periodic paralysis of Quarter Horses, severe combined immunodeficiency disease of Arabian horses, glycogen branching enzyme deficiency disease of Quarter Horses, overo lethal white foal syndrome of Paint horses, and epitheliogenesis imperfecta of Belgian draft horses). Furthermore, scientists are developing tests to measure how genes are controlled by nutrition, exercise, vaccination, infection, and the disease processes such as developmental bone diseases, muscle diseases, colic, and laminitis. Every management practice has an impact on gene expression in the horse, and we will be able to measure it.

However, integrating genomics research with veterinary applications might be challenging. Research funds for horses are often earmarked to find specific treatments for specific problems. Meanwhile, genomics research does not produce drugs or vaccines by itself. Consequently, an initiative by the Morris Animal Foundation to fund teams of scientists to address important health problems for horses is particularly noteworthy.

Morris Animal Foundation accepted pre-proposals in February for their Equine Health Consortium initiative. The goal of the consortium approach is to encourage scientists to collaborate on large scale and solve important problems for the horse industry. Proposals were submitted covering topics from respiratory diseases to lameness to colic to hereditary diseases. Over a period of five years, $2.5 million will be raised for one consortium project. The concept is not simply to put more money into research. The goal is to bring together and harness the creative energy, individual expertise, and diverse resources of scientists working on these problems worldwide. Normally, competition is a healthy activity and stimulates creative thought. However, when resources are limited, the consortium approach assures collaboration and sharing of resources between institutions and industry, even as scientists approach problems from different angles. This initiative has potential to bring together the right teams of scientists to benefit the health and welfare of horses and possibly even include applications from the new field of genomics.

Author: Dr. Ernest Bailey, 859/257-4757,, Maxwell H. Gluck Equine Research Center, University of Kentucky, Lexington, Ky.

Reprinted from Equine Disease Quarterly, Department of Veterinary Science, Maxwell H. Gluck Equine Research Center, University of Kentucky, Lexington, Ky. 40546; 859/257-4757;

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Equine Disease Quarterly

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