Discussion: Breeding Protocol

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The following is the opinion of Annette L. Gerhardt, B.S., J.D.:

I am informed that the final draft of the recommendations of the RMHA Genetics Committee to be presented to the Board on January 10, 1998, would prohibit breeding AA horses after 1998. The recommendations seek to completely eliminate the ASD gene from the RMH gene pool. What is not taken into account is that to do so would apparently also eliminate the silver dapple gene from the RMH, thus eliminating the gene which produces the beautiful colors chocolate, red chocolate and yellow silver. I do not believe this to be either necessary or appropriate. The restriction on the breeding of AA horses should only be on breeding AA to Aa or AA horses, not on breeding AA to aa. The results of breeding AA to aa would be 100% Aa horses, all only carriers with harmless cysts, none with ASD and resulting vision impairment. So, for example, breeding an AA chocolate to an aa black would result in 100% chocolate horses, all of them only carriers, all having only harmless cysts. Since it is not necessary to protect either the horses or the buying public by prohibiting the breeding of AA to aa, to do so would inflict an unneccessary economic hardship on those who are already most adversely affected by the ASD problem, the owners of chocolate, red chocolate and yellow silver horses. The sound genetic reasoning on which this opinion is based are set forth in the next thread of this discussion.(See Responsible Breeding.)

-- Annette Gerhardt (gerhardt@sinosa.com), January 01, 1998


Responsible Breeding:

It appears that the ASD gene follows the silver dapple gene almost 100% of the time. The silver dapple gene is responsible for the chocolate color in our horses. To continue producing chocolate horses, but eliminate ASD, we cannot breed a mare and stallion that both carry the silver dapple gene. This will only increase the number of ASD horses and increase the probability of dead, blind, or vision impaired foals. It is possible to breed silver dapple gene horses to non-silver dapple gene horses and get the chocolate color. Chocolates bred to true blacks (non-silver dapple gene) will produce 50% chocolates and 50% blacks. The chocolates will be Aa and, thus will not have ASD. The blacks will be aa, and will not be ASD carriers. True blacks should be black with black manes and tails with no silver hairs. Chocolates bred to true bays will produce red chocolates that are Aa. True bays should have black manes and tails with no silver hairs.

The silver dapple gene produces chocolate, red chocolate, and yellow silver. If a horse, that would be black, inherits the silver dapple gene, it becomes chocolate. The body color can range from a very light, almost blue color, to a very dark, almost black color. The mane and tail can range from white (to appear bleached) to very dark, although usually streaked with silver. Dr. Phil Sponenburg, the author of the book, "Horse Color," calls such a horse a "blue silver." A bay horse that inherits the silver dapple gene is usually called a red chocolate. The black "points" (ear tips, lower legs, mane, and tail) are affected by the silver dapple gene, but the red or brown of the body is not affected. The ear tips and legs turn some shade of chocolate ranging from very light to very dark. The mane and tail turn flax, in the same range as described above. Dr. Sponenburg, in his first edition of "Horse Color" called such horses "silver dapple bays." In his second edition, he used the term "red silver."

Not well recognized by breeders, there are also silver dapple brown bays, or brown bay chocolates, which Dr. Sponenburg calls "brown silvers." They are usually confused with blue silvers and simply called chocolate, even though they are actually a type of bay rather than a black horse that has inherited the silver dapple gene. A brown bay is a bay that lacks the gene that normally turns the body color a red bay, and so the body color is brown. A brown bay is a brown horse with black points. If such a horse inherits the silver dapple gene, the ear tips and legs are chocolate and often very close to the same color as the brown body. The mane and tail are flax. Thus, the horse may "appear" to be chocolate. If the horse produces a bay (or any derivative of bay: buckskin, red chocolate, or yellow silver) foal, the horse is actually a silver dapple brown bay, not a blue silver.

Creme is an incomplete dominant and a dilute of sorrel. Sorrels (and the variations: palomino, cremello, perlinos, and silver smokies) CAN carry the silver dapple gene, but will not show it. A sorrel (and its variations) is produced by the creme gene. Distinguishing between cremellos, perlinos, and silver smokies is not important to this discusion, therefore I will call all three cremellos. They are creme horses with blue eyes. The breeder just needs to know that any sorrel, palomino, or cremello may carry the silver dapple gene without showing it, except by the presence of cysts or ASD that are detected in an eye exam. For this reason, these horses should be tested. A sorrel horse that inherits one creme gene will be a palomino. A bay horse that inherits a creme gene will have a palomino body, but black points, and thus be a buckskin. A bay horse that inherits one copy of the creme gene, and one or two copies of the silver dapple gene, will be a silver dapple buckskin. Dr. Sponenburg calls this a "yellow silver." Sometimes, these horses have legs so light as to blend with the body, and will look like a palomino or even a cremello. They are often registered as cremellos, but they can be distinguished from cremellos because they do not have blue eyes. If, by careful examination, the legs are slightly darker than the body, they are not palominos, but yellow silvers.

A grey horse may also carry the silver dapple gene and not show it. A grey horse is born dark and turns grey and possibly white over time. Grey can be a fast grey or a slow grey. Old Soppy, an MPHA foundation stallion, was double dominant for the fast grey gene. All of his offspring turned grey by the time they were a year or two old, and white by the time they were four or five. Caudill's Casey, an RMHA foundation stallion sired by Sam, is a single dominant for the slow grey gene. He was chocolate with a flax mane and tail as a young horse. He greyed out by the time he was 8, and at 15 is still a dapple steel grey. It is believed that Casey is an Aa horse, because he is a single dominant for silver dapple, having sired both chocolate and black foals. To look at him now this would not be apparent, because he is grey. Greys that were not born clearly black or bay, or whose original color is not known, should have an eye check. Color linked eye problems are not limited to horses. Dog breeders of chocolate Labs and Standard Poodles have a similar problem. They cannot breed chocolates to chocolates or the resulting pups may have an eye problem, including blindness. They breed chocolates to blacks and get 50% chocolates and 50% blacks. In this way, the breeders are controlling the eye problem. The chocolate is a sought after color in Labs and Poodles and brings higher prices. This will also be true of our chocolate horses, because there will be fewer of them.

We should make responsible breeding decisions. It is my opinion that AA horses should be eliminated from the gene pool (breeding program). If we continue to breed these horses there will be an increase in foals that are born dead, blind, or vision impaired. That is a cruelty that I cannot advocate or condone. However, we can breed for and use the present AA horses to breed for more chocolates by breeding them to aa horses. AA bred to aa will produce 100% Aa, horses with only harmless cysts and no vision impairment. Thus, no harm is done to the horse or the horse owner. Once the AA horses are eliminated from the gene pool, chocolate will still be prized and valuable for the color, because, as in the dog breeding programs, the chocolate color can only be bred for indirectly by breeding chocolate to black, rather than bred for directly by breeding chocolate to chocolate.

In order to make responsible breeding decisions, we need to have the eyes of ALL BREEDING HORSES checked to determine their ASD status. This will provide the best information available for our near-term breeding decisions. The eye exam is not foolproof because there is a 12% incomplete penetrance factor of the ASD gene. This means that 12% of the horses with clear eyes will not be aa but actually be Aa and still carry the gene, and 12% of the horses with cysts will not be merely Aa, but will actually be AA. So, we still need to raise the funds to get the genetic marker test developed. The genetic marker test will ascertain the ASD status of each horse. It will also allow us to determine if there are, in fact, silver dapple carriers that are free of the ASD gene. If so, we will be able to breed silver dapples without the ASD gene to other silver dapples. But until that time, we should only breed silver dapples to non-silver dapples.

-- Annette Gerhardt (gerhardt@sinosa.com), January 01, 1998.

I would like to make one correction to Annette's message - it is my understanding that the RMHA Genetics Committee's recommendations to the Board re breeding restrictions include the elimination of AA STALLIONS ONLY after l998 from the certified breeding stock - no restrictions on mares have been proposed.

I have seen Gus Cothran's models for reducing the prevalence of the ASD gene in the population; I did not get the impression that they contemplate actually eliminating the presence of ASD in the population entirely, but do reduce it to much smaller numbers. When we get the genetic test we will then know how closely linked the ASD gene is to the "chocolate" gene. So far it appears to be pretty closely linked, but even nature is not perfect, and there are a lot more chocolate horses examining as normal than the 12% incomplete penetrance factor postulated, so maybe there is some hope that there are some genetically normal chocolates out there. Until we get some proof of this, however, not breeding chocolate to chocolate will probably remain good advice.

-- Paula Morgan (COPCO@webtv.net), January 01, 1998.

I have a fundamental disagreement with the goal of reducing or eliminating the ASD gene, because it is so closely tied to the silver dapple gene. As is set forth in detail in my post, I do not see that as desireable or necessary for the protection of the horses or the public. AA stallions bred to clear eyed mares should produce Aa horses with only cysts, which are not harmful to the horse. I find that much more ethical than allowing Aa to Aa breedings where we KNOW that 25% will be AA, with all the risks of ASD, vision impairment, blindness, death. Some of our most outstanding stallions are silver dapple, and many will probably be AA. To ban them from breeding does not make sense when it is simply not necessary. All should keep in mind that I have always bred first for temperament and gait, and have never been all that hot on chocolate. But it is a color that attracts people to our horses, and that many people like. Since the genetics of what I am proposing, AA to aa, is simply a lesson taken from the dog breeders who have been successfully managing similar problems for a long time, without the benefit of a genetic test, I see absolutely no reason we can not do the same thing, and thereby avoid eliminating some of our best horses of an already small gene pool, and avoid inflicting on the owners even more economic hardship than is already being inflicted by this problem.

I welcome discussion. I expected that my proposal would be controversial, and I think some people who know me well will be surprised at it, as I have always been a ferocious defender of the horses, ALL of them, regardless of the labels people have stuck on what is essentially the same horse with three different names for political reasons that have little to do with the horses themselves. Try to tell me that the double and triple registered horses I have in my paddocks are not all the same breed. I have also had a long history of telling people to look beyond the color and choose a horse for the important reasons, temperament and gait, the last being the single biggest flaw in Mountain Horses, weak gait of about 80% of them that leads to pacey horses. I could have simply kept silent, because the goal of reducing or eliminating the ASD gene, since it has the side effect of also reducing or eliminating the silver dapple gene, would force the breeders to compete with other gaited breeds on their merits, temperament and gait, and not on the color as has happened so much in the past. But I can not stay silent when I believe that to eliminate the silver dapple gene is not necessary, and when I have formulated a breeding program that will allow the use of AA horses and have them eliminated by time and attrition, rather than abrupt deletion from an already small gene pool, and thereby also save unnecessary economic hardship on those already hardest hit by the ASD problem.

Thank you all for consideration of my thoughts.

-- Annette Gerhardt (gerhardt@sinosa.com), January 01, 1998.

I think you have a valid point of view which many would share, and I agree with it up to the point of allowing AA stallions to breed. I just do not think we should have breeding stallions with ASD or other avoidable genetic defects. If there are no restrictions at all on the breeding of these horses, there will be little incentive for some people not to continue breeding as they have done in the past.

Also, even under your breeding proposal, Annette, you need a pretty good number of those normal horses around to breed the AA and Aa horses to. We are losing our population of normal-eyed horses fast. We need some encouragement to breed for them and to keep them in the breeding population. That is really what the Cothran models try to do - increase the percentage of normal eyed horses being produced so we can have them to breed to, so we will not have to produce AA horses.

As a practical matter, other than decertifying AA stallions (which I do hope they do, but they may not) I imagine people will be free to breed how they wish, which is probably a good thing. It is really the marketplace which will determine how people's breeding practices evolve.

-- Paula Morgan (COPCO@webtv.net), January 01, 1998.

My name is Becky Gage and I have been breeding Paso Fino horses for 14 years. Two years ago, I got interested in the Rocky Mountain horses, and have acquired 3 (2 colts and 1 filly) for the purpose of crossing with my Pasos. Another friend and I are doing this and we have used the term "Mountain Paso" to describe the resulting offspring. Last year, I used this friend's chocolate stallion to breed to four Paso mares.

I now have 4 of these crosses on the ground, and at least 3 carry the silver dapple gene (one colt is a bay with some white hairs along the base of his tail, which either his buckskin mother or his chocolate father could have contributed). Of the three that I am sure carry the gene, one is chocolate and two are gray with white/flaxen manes and tails. One of the grays is a filly and the other three are colts, which I plan to geld since I see no reason to allow breeding of these crosses. At the most, genetically, these offspring could be Aa (carriers), since their mothers were all Paso Finos.

All their parents plus all my Rocky Mountain bloodline horses are registered KMSHA, and two of the Rockies are also RMHA, although not currently certified to breed in that registry.

I will have the vision of my rocky horses tested in two weeks. The only one I am certain must not be ASD is my black colt, a grandson of Nuncio. I also have a "KMSHA registered only" chocolate son of Clemon's Tim, and a sorrel filly that is a full sister to Kentucky Blue.

While I am a member of both the RMHA and KMSHA, I feel like an outsider because I am not breeding pure Rocky Mountain bloodline horses. But I have a stake in what happens to the Rockies, since any negative publicity affecting the Rockies is likely to also affect my horses.

I have found the effects of the silver dapple gene to be quite interesting. I have never had a chocolate baby before, and never gray babies that were born sorrel or gray (instead of the usual dark brown), and with white or flaxen manes and tails. We have dubbed these gray babies as "white chocolates"!

Even if my chocolate and sorrel Rockies have vision impairments, I plan to breed them to my Paso Finos, since I know their offspring will not have such problems. Thus, I plan to breed AA (if I have it) to normal (aa), producing Aa. I only hope that the foals will continue to be eligible for KMSHA registration. I believe my breeding plans are more responsible than breeding known Aas to Aas, since I will never produce an AA (or ASD) horse.

The breeding protocol that I would support would simply require all horse to be vision tested. No AA could be bred to anything other than an aa. This would allow the breeders to use all of their horses, even if they had to limit the number of breedings with the AAs, due to a current shortage of aas. The effect of the silver dapple gene might produce other exotic colors when more breedings were done to non chocolate horses. It should also enhance the value of the chocolates, since there would be fewer of them.

I would propose that this protocol be followed until the time a genetic test was produced and available that eliminated the risk of ASD foals born dead or with severely impaired vision.

-- Becky Gage (bgage@neosoft.com), January 01, 1998.

One point I would like to make is this: and this is only my personal opinion.

Regardless of how we breed, AA to aa mares or stallions, Aa to aa mares or stallions, we still have a narrow gene pool. If we don't get in new blood we will have other genetic problems down the road. If you limit the AA stallions and or the AA mares this will limit the current gene pool even more.

-- Kathy Naylor (knaylor@proaxis.com), January 01, 1998.

I have been saying since 1990 when I first came in contact with these horses that it was a mistake to close the books in RMHA with about 1000 horses then registered, if memory serves me (someone correct me if I am wrong about that), because I knew and told anyone that would listen that there WOULD be genetic problems that result, and that I expected them to appear fairly quickly, because the gene pool was so very small. Nonetheless, the registry has been increasingly restricted, first by requiring CBG mares to have one Rocky Mountain parent, and recently by trying to close the gelding books, not even breeding stock for crying out loud!There have also been repeated efforts to close off even the trickle of outside blood coming in with CBG mares, by trying to close the books to CBG mares completely. The only conclusions to be drawn is that the people who back these initiatives first: do not understand or ignore the problems that WILL develop in small closed gene pools, and second, are restricting the supply of horses with the RMH registration to drive up prices. While I agree with Kathy that steps should be taken to open up the gene pool, I think that in spite of our differences she recognizes that one of the reasons I do not feel that the AA stallions should be decertified after 1998 is precisely because the gene pool is already too small, and we simply can not afford to loose even the small number of good stallions that are going to be AA, when we can use them to breed to aa mares. Paula points out that this will increase the supply of horses with the ASD gene. Yes, but in the next generation of breeing those Aa horses to Aa, if that is allowed, or better yet Aa to aa, then the number of aa horses will increase. Time and the natural replacement of stallions in breeding programs will take care of taking the AA stallions out of the gene pool. It is just not necessary for the protection of the horses or the public to do so abruptly after only one more breeding season.

-- Annette L. Gerhardt (gerhardt@sinosa.com), January 01, 1998.

If we bloodtype for proof of parentage and list on each horses registration papers its eye status, then we could breed both AA Stallions and mares. So long as those offspring are bred to clear eyed horses only. This should dilute the gene out of the breed while maintaining quality AA Stallions. My problem with this has always been irresponsible breeding tatics, If we can be assured that AA horses will only be bred to aa horses that would be much less risk of AA offspring then Aa to Aa which can produce 25% AA offspring. My feeling is I am not willing to take the risk of producing AA offspring by breeding Aa to Aa. But regardless of how we breed our Tobe decendants we are still in too small a gene pool.

-- Kathy Naylor (knaylor@proaxis.com), January 01, 1998.

I would like to clarify my answer regarding AA Mares and AA Stallions. By breeding AA mares to aa Stallions and AA Stallions to aa mares will produce Aa offspring, these Aa offspring should be bred only to aa stock to produce 50% aa and 50% Aa offspring.

-- Kathy Naylor (knaylor@proaxis.com), January 01, 1998.

I agree completely with Kathy's last two posts. I appreciate her considered review of my opinions. I am extremely glad to have met someone who cares as much about the horses as she obviously does. Without her taking the first courageous step of notifying everyone whose email address she could find, this site would not be here, and the information about the ASD problem would not have gotten out to the many people who now have it. There are many other people to thank, too, and I do not mean to slight them, but without that first step by Kathy, the rest would not have happened.

-- Annette L. Gerhardt (gerhardt@sinosa.com), January 01, 1998.

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