What Is HERDA In Horses?

You may have heard the phrase 'this horse is 5 panel NN' when purchasing a new Quarter Horse or Paint. Do you know what they're actually testing for though? These genetic tests look for five common heredity diseases in stock type horses. They're HYPP, PSSM1, MH, GBED and HERDA.

Not every horse will be NN (which means the horse is negative and doesn't carry any copies of the disease). It's important you understand what it means if your horse is positive for any of those five conditions.

Let's take a look at hereditary equine regional dermal asthenia, also known as hyperelastosis cutis or HERDA.

HERDA Explained

This genetic skin condition is commonly found in Quarter Horses and other stock breeds. It can be traced back to the popular sires Poco Bueno and King. Other famous carriers from that line include Doc O'Lena, Smart Little Lena, High Brow Cat.

In this disease, the skin has a lack of adhesion within the layers. It's a genetic defect in the collagen. The outer skin layer will split and even tear off in some cases. These horses are left with nasty scars and lesions. Most do not live very long. Furthermore, there is no cure or treatment.

To acquire HERDA, both parents must contain a copy of the mutated gene. If the sire and dam are both carriers, then the foal has a 25% chance of being affected.

Hrd/N- Horse is a carrier for HERDA, but will not have symptoms. They will pass the defective gene 50% of the time.

Hrd/Hrd- They have two mutated copies of the gene. These horses will be affected from this disorder.

With that being said, as long as a carrier is to bred to a non-carrier the disease should not be an issue. Many cutting horses are actually carriers. Some breeders find these horses to have flexible tendons.