The Dangers of Summer Stampedes for Wild Horses

Dr. Bruce Nock is a tenured faculty member at Washington University School of Medicine and founder of Liberated Horsemanship.

Wild horses face significant challenges during summer stampedes, particularly when chased by helicopters. This article explores the physiological and genetic impacts of such events, highlighting the risks posed by high temperatures and stress.

Physiological Stress from Stampedes

When wild horses are chased by helicopters, their bodies undergo severe stress. In hot and humid conditions, it can take less than 20 minutes of moderate exercise to raise a horse's body temperature to dangerous levels. The activation of the sympathetic nervous system during a chase exacerbates these risks, potentially leading to dehydration, colic, convulsions, and even heart and renal failure.

Horses can sweat up to 30 liters per hour, losing not only water but also essential minerals and trace elements. Simply replenishing water is insufficient; electrolytes are necessary to prevent exacerbating dehydration.

Impact on Young Foals

The summer months are particularly perilous for foals, who are only a few months old. While young animals might seem resilient, early development is a fragile period where stress can have long-lasting effects. This is where the concept of epigenetics becomes relevant.

Understanding Epigenetics

Epigenetics involves the microenvironment surrounding a gene, which influences gene activity. For instance, the same genes in a calico cat produce different colored spots due to variations in the epigenome. Similarly, epigenetic differences determine the development of organs like the heart, liver, or brain.

While genes are fixed, the epigenome can change throughout life, affecting gene activity. Adverse conditions early in life can cause epigenetic marks that negatively impact health and stress reactivity throughout an animal's life.

Long-term Consequences

Some epigenetic marks may be inheritable, affecting future generations despite extensive reprogramming during early development. This means that the actions of the Bureau of Land Management (BLM) not only impact the current generation of wild horses but could also affect their descendants.

For more detailed insights, refer to Dr. Bruce Nock's work, "Wild Horses—The Stress of Captivity," commissioned by the American Wild Horse Conservation (formerly American Wild Horse Preservation).