A Guide to Curly Horse Genetics

The genetics of curly horses, a unique and fascinating type of horse known for their distinctive coat, have long intrigued equine enthusiasts. To preserve and deepen our understanding of these extraordinary animals, the International Curly Horse Organization (ICHO) has partnered with Etalon Equine Genetics to get to know these horses down to their DNA. Together, we are leading the charge in unraveling the genetic mysteries behind curly horses while fostering responsible breeding practices. We recently sat down with Bunny Reveglia from the International Curly Horse Organization and Dr. Mitch Wilkinson, their research director, to talk all things curly on the Unbridled Genetics podcast. Let’s recap what we learned!

What Makes Curly Horses Unique?

Curly horses stand out because of their distinct curly coat, which is more than just an aesthetic feature. These horses typically sport a dense, curly coat in the winter, resembling sheep, and transition to a smooth coat in the summer. Many curly horse owners and enthusiasts celebrate these horses for being widely reported as hypoallergenic, although the scientific community is still investigating the reasons behind this unique characteristic.

Despite the curly coat’s outward charm, there is a complex genetic landscape behind it. Curly horses are not actually a specific breed despite what most people think, but rather a type of horse defined by genetic mutations that affect the coat. Research has revealed several mutations responsible for these curls, with two genes, keratin 25 (KRT25) and transcription factor (SP6), being particularly significant in North American populations, including Mustangs and Missouri Fox Trotters.

The Importance of Genetic Testing

Genetic testing plays a vital role in preserving curly horses and making informed breeding decisions. With the discovery that curly horses can inherit multiple curly mutations simultaneously, breeders must navigate the complexities of these mutations to avoid potential coat problems. Some combinations of mutations may lead to hair growth issues like hypotrichosis or alopecia, conditions that are becoming more common as curly horse breeding practices evolve.

Mutations in the KRT25 gene specifically are associated with hypotrichosis, a rare condition in horses characterized by hair loss or the inability to grow hair. It may occur in specific areas or across the body, often symmetrically and primarily affecting the face. The skin in the affected regions may appear scaly and feel thinner than usual. With genetic testing from Etalon, your horse would be evaluated for mutations at both the KRT25 and SP6 genes. Their results would look like a combination of the following:

Curly Coat 1 (CU1)

CU1/CU1 = homozygous for Curly Coat at KRT25, curly coat & complete/persistent hypotrichosis

CU1/n = heterozygous for Curly Coat at KRT25, curly coat & incomplete hypotrichosis

n/n = no KRT25 variant detected

Curly Coat 2 (CU2)

CU2/CU2 = homozygous for Curly Coat at SP6, curly coat trait expressed

CU2/n = heterozygous for Curly Coat at SP6, curly coat trait expressed

n/n = no SP6 variant detected

The partnership between ICHO and Etalon Equine Genetics ensures that genetic testing is a core component of the registration process for curly horses. By testing for curly coat genes, breeders are empowered to make better-informed decisions, safeguarding the health and appearance of the horses they produce. Curious to know what’s causing your horse’s curls? Check out either our Standard Package or Pro Package to find out what curly genes they may carry!

The Role of Genomic Inbreeding Testing

One of the critical tools Etalon Equine Genetics brings to the table is genomic inbreeding value testing, part of our Ancestry Package, which provides a more accurate measure of inbreeding in small populations like the curly horse community. Traditional pedigree estimates often fall short in representing the true genetic overlap between horses. By using genomic data, breeders can more accurately assess the risks of inbreeding and make strategic decisions to maintain genetic diversity.

The collaboration between ICHO and Etalon Equine Genetics demonstrates the importance of combining modern genetic testing with thoughtful breeding practices to protect the future of curly horses. Through ongoing research and the application of cutting-edge genetic tools, the curly horse population can continue to thrive, ensuring that these unique and captivating animals remain part of our equine world for generations to come.

A Growing Body of Research

What makes curly horses even more intriguing is that spontaneous mutations still occur, leading to new variations of the curly coat gene being documented. Additionally, some horses may exhibit curly traits even when testing negative for known curly coat genes. This suggests that there are still undiscovered curly mutations waiting to be uncovered—a mystery that keeps all of us in the research community invested in further exploration.

Genetic research has also highlighted the differences between specific curly horse genes and their potential applications. For example, fiber testing has shown that the KRT25 and SP6 mutations result in different fiber properties, which may influence their suitability for spinning similar to wool or mohair. This opens up an exciting avenue for further research into how these genetic variations might affect not only breeding practices but also potential uses for curly horse hair!

Conclusion

The partnership between the International Curly Horse Organization and Etalon Equine Genetics represents a significant step forward in understanding and preserving the genetics of curly horses. With advancements in genetic testing and a commitment to responsible breeding, this collaboration is paving the way for a healthier, more robust population of curly horses. As research continues to uncover new mutations and insights, the future looks bright for these incredible animals and the dedicated community of breeders and enthusiasts who support them.