The AQHA recommends owners screen their Quarter Horses for five diseases: glycogen branching enzyme deficiency (GBED), heredity equine regional dermal asthenia (HERDA), hyperkalemic periodic paralysis (HYPP), malignant hyperthermia (MH), and polysaccharide storage myopathy (PSSM). | Photo: iStock

Audrey Kelleman, DVM, Dipl. ACT, clinical assistant professor and large animal reproduction service chief in the University of Florida’s Department of Large Animal Clinical Sciences, described the importance of this test during the university’s 2020 Healthy Horses Conference.

First, a Primer on Genetics

Kelleman defined genetics as the way physical traits and characteristics get passed from one generation to the next—also called heredity. Genetics includes the study of genes, which have a special code called DNA that determines physical traits and susceptibility to certain illnesses.

“Our bodies are made up of cells, and within those cells are a center portion called the nucleus,” she explained. “The nucleus has chromosomes that contain genetic material for our bodies. Horses have 32 pairs of these chromosomes, making 64 total. A foal gets one copy from the mare and one from the stallion. If we unfurl these chromosomes, they have genes contained on them