Completed Projects
Immune Mediated Myositis (IMM)
Equine immune-mediated myositis (IMM) is a disease occurring in Quarter horses and QH-related breeds that typically causes rapid and severe symmetrical wasting of the topline muscles, often following exposure to or vaccination against respiratory infection by Streptococcus equi, the organism responsible for equine “Strangles”. The loss of muscle mass is primarily attributable to inflammatory destruction of fast-twitch muscle fibers, with a diagnosis of IMM being based on biopsy of the atrophied muscle and identification of invasion of muscle fibers and local blood vessels by T-lymphocytes and macrophages, two types of white blood cells involved in adaptive immune responses and the clean-up of cellular debris. Full muscle mass can be regained within several weeks to months. However, approximately 40% of horses affected by IMM will experience at least one recurrence of an atrophic episode, with the extent of muscle loss and resultant decrease in quality of life being severe enough in some cases to warrant euthanasia. Among Quarter horses, IMM appears to be especially prevalent in reining and cow types (Gianino G, et al. J Vet Intern Med 2019) and has a strong familial relationship, suggesting that predisposition to this disease has a genetic basis. In collaboration with Dr. Stephanie Valberg at Michigan State University, the Finno Lab has identified a genetic variant that confers susceptibility to IMM (Finno CJ, et al. Skeletal Muscle 2018).
Idiopathic Hypocalcemia
Hypocalcemia, or low calcium concentrations in blood, can be due to a wide variety of causes. Hypocalcemia impairs maneuverability of limbs and weakens bones. Severe hypocalcemia may also result in seizures, muscle fasciculations, ileus, tachycardia, synchronous diaphragmatic flutter, and ataxia. In horses, many cases of hypocalcemia are due to hypoparathyroidism or sepsis. However, there appears to be an inherited form of hypocalcemia in Thoroughbred foals for which the cause has not yet been determined. It is hypothesized that idiopathic hypocalcemia in Thoroughbred foals is due to a genetic mutation. Currently, this idiopathic disease has only been identified in Thoroughbreds. All clinically affected foals die or are euthanized due to the severity of this disorder. In a joint effort with Dr. Gary Magdesian, our lab is currently investigating a potential genetic mutation responsible for idiopathic hypocalcemia of Thoroughbred foals.
Atypical Equine Thrombasthenia (AET)
In collaboration with Dr. Fern Tablin, we are investigating the genetic etiology of Atypical Equine Thrombasthenia (AET) in Thoroughbred racehorses. On one breeding farm, AET occurred in 1:150 Thoroughbreds. Based on pedigree analysis, the disease appears to be heritable. This disease can be diagnosed by determining the extent to which platelets bind fibrinogen, with affected horses binding 35% or less fibrinogen than a healthy horse. Currently, genetic variants are being investigated to identify one that appears to be associated with AET.
AET is characterized by prolonged bleeding and epistaxis, or nose bleeding, caused by an inability for the horse to clot normally. This disease has currently only been diagnosed in the Thoroughbred breed.