What Is Herda in Horses? Causes Explained & Key Facts

Imagine running your hand over a horse’s sleek coat, only to feel patches of loose, fragile skin that tear at the slightest touch. For horses affected by HERDA, this isn’t just a rare discomfort—it’s a dailyreality. This genetic condition, though uncommon, leaves a lasting impact on the horses and the people who care for them. Let’s unravel what HERDA really is and why it matters to breeders, riders, and veterinarians alike.

What Is HERDA in Horses? Causes Explained

HERDA (Hereditary Equine Regional Dermal Asthenia) is a rare, inherited skin disorder that primarily affects Quarter Horses and related breeds. Often called "hyperelastosis cutis," this condition weakens the skin’s connective tissues, making it abnormally fragile and prone to tearing. Even routine activities like saddling or grooming can cause painful lesions. But let’s be honest—HERDA isn’t just about fragile skin. It’s a lifelong challenge that demands careful management and deep compassion.

The root cause? A genetic mutation in the PPIB gene, which disrupts collagen production. Collagen acts like the glue holding skin layers together, and without it functioning properly, the skin loses its elasticity and strength. The mutation is recessive, meaning a horse must inherit two copies (one from each parent) to develop HERDA. Carriers—horses with just one copy—show no symptoms but can pass the gene to offspring. This makes genetic testing crucial for responsible breeding.

Signs typically appear when the horse is young, often between six months to two years old. You might notice loose folds of skin, slow-healing wounds, or scars from minor injuries. In severe cases, the skin may even detach from the underlying tissue. While there’s no cure yet, understanding HERDA’s causes helps breeders make informed decisions and gives affected horses a better quality of life.

The Genetic Puzzle: How HERDA Spreads

HERDA’s inheritance pattern is a classic example of recessive genetics. Both parents must carry the defective gene for a foal to be affected. Statistically, if two carriers are bred, there’s a 25% chance their offspring will have HERDA, a 50% chance the foal will be a carrier, and a 25% chance it’ll be free of the mutation entirely. This makes genetic testing not just helpful—it’s ethical.

The mutation’s prevalence is highest in performance-bred Quarter Horses, particularly those from cutting or reining lines. Some suspect the famous stallion Poco Bueno may have introduced the gene into the breed decades ago. Today, responsible breeders use DNA tests to screen for carriers, reducing HERDA’s spread. It’s a slow process, but progress is being made.

Identifying HERDA: Symptoms and Diagnosis

Spotting HERDA early can save a horse from unnecessary pain. Key symptoms include:

• Hyperextensible skin that stretches abnormally
• Easy bruising or tearing, even from light contact
• Slow-healing wounds and scarring
• Loose skin folds, especially along the back or pressure points

Diagnosis involves a combination of clinical signs, skin biopsies (which show disorganized collagen fibers), and genetic testing. A definitive DNA test, developed in 2007, can confirm whether a horse is clear, a carrier, or affected. Early testing is a game-changer for breeding programs.

Living with HERDA: Care and Management

While HERDA can’t be cured, careful management improves quality of life. Affected horses need:

• Protective gear: Soft saddles, padded wraps, and fly masks prevent injuries.
• Skin care: Regular cleaning and moisturizing reduce infection risks.
• Environment control: Smooth, clean surfaces and shade minimize trauma.

Some horses adapt well to light work, but most are retired to pasture. The key is minimizing skin stress while keeping them mentally stimulated. It’s a balancing act that requires patience and creativity.

The Bigger Picture: HERDA’s Impact on Breeding

HERDA has forced the horse world to confront tough questions about genetics and ethics. While carrier horses are healthy, breeding two carriers perpetuates the cycle. Many registries now recommend testing, and some even restrict carrier-to-carrier matings. It’s a step toward eradicating HERDA—but education is just as important as regulation.

The takeaway? Genetic diversity matters. Outcrossing to non-carriers or using tested stallions reduces risks without sacrificing bloodlines. For breeders, it’s about looking beyond short-term gains and prioritizing the breed’s long-term health.

When you stand beside a horse with HERDA, you see resilience in motion. These animals, despite their fragile skin, often exhibit a quiet strength that humbles everyone around them. While science searches for better treatments, our role is clear: breed responsibly, care deeply, and advocate for the horses who can’t speak for themselves. Every small step toward awareness is a stride toward a future where HERDA is a footnote in history—not a life sentence.