HC/HERDA Update; Owners of Carrier Stallions Notified

Approximately 100 Quarter Horse stallion owners have received, or will receive, a telephone message from Ann Rashmir, DVM, MS, Dipl. ACVS, associate professor of surgery and head of the Hyperelastosis Cutis (HC) Research Program at Mississippi State University, that contains unwelcome news. The message is that the stallion is a carrier of the recessive gene that causes HC, also known as hereditary equine regional dermal asthenia (HERDA).

Being a recipient of that information, says Steven Hanson, a Billings, Mont., attorney as well as a cutting horse exhibitor and breeder, just might serve to place a special responsibility on the stallion owner to reveal to mare owners that the stallion is a carrier.

Rashmir says she has no immediate plans to make the names of the known carrier stallions public.

"I think it is only fair that the owners should be informed first," she said. "They shouldn't have to read about it in a publication. My hope is that they will then make this information available to persons planning to breed mares to their stallion or stallions."

The stallions known to be carriers are those which have sired an HC-affected offspring. Siring even one HC offspring is proof that the stallion is a carrier, says Rashmir.

Rashmir and Nena Winand, DVM, PhD, a geneticist and assistant professor in the Department of Molecular Medicine at Cornell University, announced earlier that 100% of the horses they have studied which are afflicted with HC trace through both sire and dam to Poco Bueno or his immediate relatives--Poco Bueno's sire, King, and Poco Bueno's full brother, Old Granddad. Rashmir and Winand are collaborators on HC research.

What is HC?
When a horse has HC, there is a lack of adhesion within the dermis, the deep layer of skin, due to a collagen defect. Collagen serves as a form of glue that holds the skin layers together. In horses with HC, the "glue" is inferior and the skin layers separate. When the horse is ridden under saddle or suffers trauma to the skin, the outer layer often splits or separates from the deeper layer, or it can tear off completely. It rarely heals without disfiguring scars. New damaged areas arise continuously, sometimes without obvious trauma. Click here to see images of HC/HERDA.

The condition has manifested itself more frequently in cutting horses, but other disciplines are not immune, with cases showing up in reiners and pleasure horses which trace back to Poco Bueno.

Because the condition is caused by a recessive gene, it means that both sire and dam must possess the gene before an offspring of the two will be afflicted. Even when both sire and dam possess the gene, the disease will not necessarily be manifested. Under the laws of genetics, if a carrier is bred to a carrier, 25% of the offspring will have HC, 25% will not be afflicted or be carriers (they'll be genetically normal), and 50% will become carriers but not be afflicted.

One of the reasons that HC rears its head more often in cutting horse circles than any other, it is theorized, is that one of the most popular lines traces back to Poco Bueno through Doc O'Lena and Dry Doc and their dam, Poco Lena, a daughter of Poco Bueno. Both Doc O'Lena and Dry Doc are proven carriers of the recessive HC gene. Through the years, cutting horse breeders have tended to utilize the Doc O'Lena and Dry Doc bloodlines on both sides of the pedigree--breeding cousins to cousins. In essence, they have created a gene pool of carriers.

"It isn't the horse's fault," says Rashmir. "The problem revolves around the way we have bred them. Carriers have been bred to carriers. Breeders have a responsibility to avoid doing this if they know that stallion and mare are indeed carriers."

This does not mean, she says, that one should avoid the Poco Bueno bloodline when establishing a breeding program.

"If you owned Poco Bueno and knew that he had a genetic flaw, would you have stopped using him as a breeding stallion?" she asked rhetorically. "Not at all. He was a wonderful athlete and a great progenitor, but you would have, or should have, worked around the problem by avoiding inbreeding. It's the same with many of his descendants. They are great athletes and even if they are carriers, it has no effect on their performance capability. Simply having the recessive gene produces no harm to that individual. The problem arises when carrier is bred to carrier, setting the stage for HC to be manifested."

The American Quarter Horse Association (AQHA) is funding research at the University of California, Davis, aimed at finding a genetic marker for the disease. Researchers say they are two to three years away from being able to identify the recessive gene.

AQHA also has funded research at Mississippi State where Rashmir and associates are attempting to establish a protocol for dealing with afflicted horses. While the disease is a death sentence for many, Rashmir said, there has been some progress in developing ways to mitigate the effects of HC. Some afflicted horses, she said, have been able to perform in at least a limited manner.

Owners of Carrier Stallions
What are the legal ramifications when a stallion owner knows that his horse is a carrier? Is he/she bound to disclose that information to mare owners?

We asked attorney Hanson to respond to that question. Here, in part, is what he had to say:

"Because apparently there is no method yet developed to test through tissue biopsy for carrier status in breeding stock, at present the only known method of determining whether a mare or stallion is a carrier, if not themselves affected, is to confirm the existence of the condition in affected offspring. The production of an affected offspring means that both sire and dam are carriers.

"That begs the question of whether the stallion owner should make disclosure once he has knowledge of his sire's carrier status," continued Hanson. "If a mare owner has a known carrier, or a mare with known carrier ancestors, he can avoid producing an affected foal by mating the mare with a non-carrier stallion; but if the mare owner is unaware of a prospective sire's carrier status, and the owner of the stallion does not disclose the stallion's genetic flaw, does the mare owner have a legally enforceable cause of action against the stallion owner in the event the resulting offspring is affected with HC?

"Normally, saying nothing stands a better chance of avoiding legal liability than saying the wrong thing; i.e., speaking falsely or in a manner that misleads," added Hanson. "When dealing with fraud or misrepresentation, however, silence may be construed as actionable.

"Fraud and misrepresentation, as causes of action against the speaker, are usually associated with contract cases where the damaged party was either intentionally or negligently induced to enter into an agreement and then later discovered, to his detriment, that the other party had misrepresented or falsely stated a material fact upon which the damaged party had justifiably relied," Hanson explained. "The other party could even be held liable for damages, whether or not he intended to actually cause harm to the innocent party, if by saying nothing he covered up a fact that is construed as information that would be material to the unsuspecting party in making a breeding decision.

"The courts in such cases give consideration to numerous factors, or elements of proof, and of course each case will be decided on its own merits," he added. "In general, it may be said, however, that failure to disclose a known defect in the quality of the goods which are the subject of the contract could indeed be a basis for an award of damages against the silent non-disclosing party to the contract.

"In the end, even though it may have an adverse impact in the form of reduced breeding fee sales, owners of stallions which are known HC carriers may be placing themselves in legal jeopardy if they fail to make disclosure of the existence of the genetic defect in their breeding sires," Hanson stated. "The duty to disclose may also extend to sellers of young horses which have not exhibited the outward manifestations of HC, but which are the offspring of known carriers."

Hanson has personal experience with HC, although inadvertently. It is a story that is being told here because it demonstrates the insidious manner in which HC can surface.

Hanson purchased a promising son of the late Shorty Lena--tracing back to Poco Bueno through Doc O'Lena and Poco Lena. Wondering if the young horse was stallion material, Hanson offered to breed the stallion, free of charge, to a mare owned by a friend. At the time, Hanson and the mare owner knew little about HC. The mare's granddam, traced directly to Poco Bueno through a grandparent and a great-grandparent.

The mare, bred to Hanson's stallion, produced what appeared to be a quality filly. Before reaching one year of age, however, she manifested clinical signs of HC. A biopsy was sent to Mississippi State University. The diagnosis was hyperelastosis cutis.

Hanson did not face any major decisions as to how to handle the situation because, before learning that the stallion was a carrier, he had decided that standing a stud wasn't for him and the horse was gelded. The mare owner had not paid a breeding fee, so there were no damages from that aspect.

Hanson concluded his remarks on legal obligation involving HC carriers thusly: "The duty to disclose, or lack thereof, presents a moral as well as a legal dilemma. Ethicists may argue the question at length, but in the final analysis, each owner of a known carrier stallion will settle that debate for himself in his own mental wrestling match.

"As to the legal question, persons suffering damage in consequence of misrepresentation by silence are urged to seek the advice of an attorney who can render an opinion after consideration of all the facts and the law of the state which has jurisdiction over the parties and the subject matter of the breeding contract," concluded Hanson.

While there are approximately 100 known carrier stallions, they are only the tip of the iceberg, said both Rashmir and Winand. They fear that there are a great many others which have either sired affected offspring or which have the potential to do so.

Cutting horse trainer James Johnson of Casper, Wyo., purchased a quality two-year-old prospect from a breeder. The horse's lineage traced back to Poco Bueno through Doc O'Lena. Johnson took the horse to his ranch and turned it out in a pasture with some other horses. One day he noticed the colt had what appeared to be a slight tear in the skin on his neck. Johnson surmised that a young Longhorn bull in the same pasture might have been responsible. The wound was treated, but it didn't heal. Later, it appeared to heal, but lesions opened in other parts of the colt's body. Veterinarians were called in and specialists were consulted. Although no biopsy was taken, the conclusion was that the young horse was afflicted with hyperelastosis cutis.

"It was awful," Johnson said. "He just never healed."

The veterinarians said there was nothing further they could do and the youngster was put down.

The next question is this: Will knowing that a stallion is a carrier dissuade mare owners from breeding to him when the mare might also be a carrier? The answer is sometimes yes, sometimes no. One breeder, who requested anonymity, said he is willing to take his chances breeding carrier to carrier because the bloodlines with which he is involved are producing winners in the cutting pen. He has the financial means to take the risk.

There is another side to the coin. One breeder who feels she has suffered a damaging financial loss due to HC is Cindy Lyles of Haslet, Texas. She bred her mare and did an embryo transfer. When flushed, the mare produced two viable embryos and each was implanted in a surrogate mare. Two foals were born. Both of them demonstrated outward signs of HC early in their lives. Further analyses, including biopsies, proved they were afflicted. Lyles has donated the two colts to the HC research herd at Mississippi State University.

The woman estimates that she has invested $17,000 in the breeding fee, embryo transfers, and veterinary bills. Both sides of the pedigree trace back to Poco Bueno through Doc O'Lena. 

Until a genetic test is established that will determine carrier status, the horse owner is left with guesswork in many cases when Poco Bueno bloodlines are involved. As an assist, Rashmir has offered to analyze pedigrees and provide information concerning the odds of a particular mating producing a foal with HC. The charge for an eight-generation pedigree analysis is $25 with the proceeds going directly to the Mississippi State University HC research fund.

Rashmir also has advised stallion and mare owners to include a provision concerning HC in their breeding contracts in case a foal is affected.

About the Author

Les Sellnow

Les Sellnow is a free-lance writer based near Riverton, Wyo. He specializes in articles on equine research, and operates a ranch where he raises horses and livestock. He has authored several fiction and non-fiction books, including Understanding Equine Lameness and Understanding The Young Horse, published by Eclipse Press and available at www.exclusivelyequine.com or by calling 800/582-5604.

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