June 30th 2025
WRITTEN BY Valerie de Vries
What Makes a Horse Breed Endangered?
Category: Conservation
Across the world, horses have shaped cultures, powered economies, and supported generations. Yet, many unique horse breeds are quietly disappearing, their genetic legacies at risk of vanishing forever. But what exactly makes a horse breed endangered? At the Equine Legacy Project, our mission is to raise awareness for rare and endangered horse breeds and inspire action to protect these irreplaceable animals before it’s too late. Below, we explore the criteria for endangerment, the threats to genetic diversity, and the global conservation efforts that offer hope for the future.
- Population Size: Many conservation groups have developed their own classification systems for ranking a breed’s risk level. For example, The Livestock Conservancy classifies a breed as “critical” if there are fewer than 2,000 animals worldwide, or “threatened” if the number is below 5,000. Other factors that may be considered include the number of active breeders, the breed’s geographic distribution (whether they are concentrated in one area or spread across the world), and trends in population decline.
- Genetic Diversity: Low genetic variation within a breed increases vulnerability to disease, infertility, and environmental changes. Effective population size and inbreeding coefficients are key indicators used to evaluate genetic health. One of our seven breeds, the Sorraia horse, is critically endangered with only around 350 individuals worldwide. While Sorraias have not yet faced major disease issues, they do experience infertility problems and have a high inbreeding coefficient. In the Sorraia’s case, this means that all the horses are closely related.
- Breed Management: The existence of a breed association, conservation program, and access to preserved genetic material (such as semen or embryos) are also important factors in risk assessments. For example, the Clydesdale—one of our featured breeds—benefits from breed associations around the world. Some breeders in Scotland even send semen to breed enthusiasts in other countries, making it easier for people outside Scotland to help preserve and breed Clydesdales.
Defining Endangerment:
When Is a Horse Breed at Risk?
"Every living being is nature’s finest creation. Losing them would mean erasing her art forever."
Figure 1. A simplified extinction vortex for endangered horse breeds.
The Extinction Vortex: How Small Populations Spiral Toward Extinction
One of the most serious threats facing endangered horse breeds is the so-called “extinction vortex.” This concept describes how small populations become trapped in a cycle of decline:
“As a breeding population shrinks, it can become dangerously inbred, resulting in low conception rates, poor semen quality, and increased neonatal mortality. This creates what biologists are calling an ‘extinction vortex.” (1)
There are several types of extinction vortices, but for horses, the most relevant are those driven by genetic factors. As numbers dwindle, inbreeding and genetic drift (random loss of genes by chance) reduce diversity, further weakening the population and making recovery increasingly difficult. Over time, this spiral can lead to extinction if not addressed.
"The loss of rare alleles and unique genetic combinations means that once a breed is gone, its contribution to the broader equine legacy is lost forever."
Genetic diversity is the foundation of a breed’s resilience. Unfortunately, modern horse breeds have lost significant diversity in just the last two centuries—on average, over 16% compared to their ancestors (2). Selective breeding for specific traits, such as speed or appearance, has further narrowed the gene pool. For example, the Puerto Rican Paso Fino, one of Equine Legacy Project’s horse breeds, has been selectively bred on their gait for generations, and this has reduced their genetic diversity considerably.
The loss of rare alleles and unique genetic combinations means that once a breed is gone, its contribution to the broader equine legacy is lost forever.
Loss of Genetic Diversity: Why It Matters
- Inbreeding: As populations shrink, the risk of breeding closely related animals increases, leading to health problems and reduced fertility.
- Habitat Loss and Changing Roles: Mechanization and urbanization have reduced the need for traditional working horses, leaving many breeds without a clear role or economic value.
- Crossbreeding: Hybridization with more common breeds can dilute unique genetic traits, further endangering rare breeds. This is for example how the direct ancestor of the endangered Fell Pony, the Galloway Pony has disappeared.
- Limited Resources for Conservation: Insufficient funding, expertise, and manpower often leave breed organizations unable to fully realize their conservation goals. You can read here more about how you can help these organizations
Threats Facing Endangered Horse Breeds
"By understanding what makes a horse breed endangered and supporting global conservation efforts, we can ensure that these magnificent animals continue to enrich our world for generations to come. Will you help preserve them?"
Ways to help
- Selective Breeding Programs: Carefully managed breeding plans help rebuild population numbers and maintain genetic diversity.
- Finding New Purpose: As the traditional working roles of many horse breeds have disappeared, new opportunities have also emerged for people to enjoy and appreciate these horses. For example, the surefooted yet endangered Mountain Pleasure Horse, once essential for transportation in the Appalachians, is now celebrated for its exceptional abilities as a trail riding horse.
- Genetic Resource Banks: Collecting and storing genetic material ensures that rare genes are preserved for future generations.
- International and Cross-disciplinary Collaboration: Conservation is most effective when breeders, scientists, and organizations work together across borders.
- Public Awareness and Support: Projects like ours, the Equine Legacy Project, use storytelling, photography, and education to inspire action and connect people to the fate of endangered horses.
Global Conservation Efforts: A Ray of Hope
Get the book
At the Equine Legacy Project, we believe every horse breed is a living piece of history, culture, and biodiversity. Our mission is to give a voice to endangered horses, educate the public, and support the conservation efforts that can secure their future. Learn more about our vision and how you can help on our mission page.
If you’re inspired to support our work and discover the beauty of these rare breeds, consider purchasing our coffee table book—a celebration of equine diversity and a call to action for conservation. Visit our buy page to make a difference today.