Regarding the possible future DNA testing for Chondrodysplasia-like Dwarfism

[Debby - LB]

Charlotte up until Janes post I think we all (I know I was) were including ALL Miniature Horse registries...actually simply "The Miniature Horse" in general in our remarks. I think Jane specified AMHA because over there in England the little AMHA horse is their ideal since they measure different but I could be wrong.

Anyway to answer your question since all mine were under 34 and double reg. Yes if it were brought up to vote I'd want mandatory testing to include AMHA and AMHR.

I may be wrong about this but it's my understanding that in the rules if a Miniature Horse is a dwarf (to me a horse that has dwarf characteristics is a dwarf) it cannot be registered? In my initial post I said "it is my hope that eventually this will be mandatory testing for breeding stock but I know that would be way in the future."

If the rules do state that dwarfs can't be registered... then the test actually should be mandatory when it's available but that's only my opinion.

Straight Shetlands I never dealt with at all, I went from 15 - 17 hands to less than 8 hands I never stopped in the middle LOL.. but sure if they fall within being a Miniature Horse I'd test those too heck if I had a taller one whose bloodlines I were using or in my programs pedigree I'd test it because this is our start at eradicating this gene or genes.

I've got to ask this so if anyone knows the answer please.. how would anyone know the number of dwarfs being produced had dropped substantially from early years? I mean I would hope that they have, surely they have considering way-back-when they deliberately bred dwarves but how would someone be expected to actually know this?

There are still many dwarfs aborted and born every year just like there are many dwarfs registered.

I do agree committed breeders are breeding out undesired characteristics. The little horses are definitely getting better! I can look back in my years stash of magazines and the difference is amazing. I really don't see way fewer miniature horses with dwarf like features, those are still plentiful imho but I am seeing way more miniature horses with more horse like conformation than there was.

 

[susanne]

And what if this same stallion is himself or is producing World Champion horses? Don't say it doesn't happen because I am pretty sure it does (or did)....

I don't care if it were Buckeroo himself, I would not breed a horse with the dwarf gene. Even with a gelding, I would want to know before buying, as that would speak volumes about the seller's ethics. If they were selling a gorgeous stallion gelded because he tested positive, I would be all the more likely to want to buy from them.

The good thing is, this test combined with DNA will enable people to choose for themselves. Just because some will breed does not mean others have to buy.

My question is, how important do we really consider eliminating the dwarf gene? Is the industry serious, or is it just lip service?

As for AMHR and Shetlands, while I wouldn't necessarily say that this is where testing should begin, once the test is available I feel that ALL very small horses should be tested. I don't buy the claim that Shetlands are totally free of the dwarf gene -- as was pointed out, miniatures are largely from Shetlands and the gene didn't just magically apear. Shetlands do have a much larger gene pool, and smaller stock in the past were not valued until the invention of the miniature horse. We'll never know, however, unless people test.

Whether it be testing small horses for the dwarf gene or humans for Alzheimers or ALS, to not test is to bury one's head in the sand. It may be painful to learn the results, but I want to know.

 

[BSharpRanch]

Playing Devil's advocate...What happens if an extremly large percentage of minis do test positive for the gene? Then what? At what percentage of the population of minis would we decide that the breed needs those individuals that carry a dwarf gene? 20%? 30%? 40%? 50%? If you start to sterilize everyone that tests +, and it only leaves those horses that are untested and those that test -, where will it leave a.closed book breed, if a large percentage of those horses are + and sterilized?

 

[targetsmom]

Playing Devil's advocate...What happens if an extremly large percentage of minis do test positive for the gene? Then what? At what percentage of the population of minis would we decide that the breed needs those individuals that carry a dwarf gene? 20%? 30%? 40%? 50%? If you start to sterilize everyone that tests +, and it only leaves those horses that are untested and those that test -, where will it leave a.closed book breed, if a large percentage of those horses are + and sterilized?

My point exactly! I made this point early in this thread, that until we know what percentage of minis (however they are defined) carry the dwarf gene it is premature to try to decide their fate. And let's be realistic, like others have pointed out, the powers that be in the registries will never make dwarf testing mandatory. Well, not in my lifetime anyway. But as I said earlier, I think it will be a huge improvement to have the test available, and let the test results take care of themselves through advertising (or lack thereof). I think even with the test it will be difficult to know the extent of the gene in the population because only those animals that have never produced a dwarf will likely be tested. So I would expect the rate of the dwarf gene in that population to be very low. Of course others might test to see which dwarf genes their horses carried, but I wouldn't count on it.

When this discussion started on Facebook it was an offshoot of a discussion on AMHA closing their books. I said I thought this was a very poor time to do that just when the dwarf test was about to come out. Let's get a better idea of how many AMHA minis carry the gene(s) before we close the books!

 

[Minimor]

Actually, susanne, isn't that more or less what a generic mutation is? Not a magical change, but nevertheless a change in the DNA...and John says this appears to be a relatively new mutation, so it may have suddenly appeared in one family of horses. It hasn't necessarily been passed down through generations of ponies. I know many would like to blame it on the Shetlands.

 

[susanne]

I'm not looking to blame anyone; I just want to know. Minimor, you're correct about mutations springing up, but when I consider the origins of the minature horse and the fact that it came largely from the tiny Shetlands, pit ponies and other tiny grade ponies, we shouldn't deny any possibility and would be wise to test all. I hope that it is proven that Shetlands are at least largely free of this gene, as that is where many future miniature horses will come from if much of the current stock tests positive. (I know...those are fighting words...sorry, but I believe what I believe.)

What happens if an extremly large percentage of minis do test positive for the gene?

Those who are serious about eliminating the dwarf gene will no longer breed those horses that test positive, even to negatives. Others obviously will consider themselves to be in the clear as long as they don't breed positive to positive. Again, it all depends upon how serious people are about eliminating the dwarf gene from the miniature horse. I'm simply saying that MANY will choose not to buy the resulting foals, choosing those that are dwarf gene-free, be they miniature or Shetlands.

 

[BSharpRanch]

Okay, let's say unrealisticly, that all breedable, registered minis are tested (not including geldings or spayed mares). The results come back with the staggering number of 50% positive dwarf carriers. You have now removed 50% of the breeding population. So where is that going to leave the breed? The gene pool will be awful shallow with a closed book.

 

[Debby - LB]

"So where is that going to leave the breed?" Closer to actually becoming a breed I think. People who have been seriously picking and choosing to breed only non characteristic horses by phenotype only are already dealing with a shallow gene pool, being able to use genotype will make it even shallower. You have to look way into the future to see what a legacy this will leave!

 

[rabbitsfizz]

I actually have to say I do not believe the dwarf genetic came from AmShets but from the UKShets- this would explain the higher incidence of dwarfism in AMHA horses. 35 years ago I was dealing with dwarfs bred from UKShets so it was around then. Of course the sensible breeders (this was 35 years ago, remember) had a quick answer to the problem, but no idea whatsoever where it came from or why it happened. A friend had an achondroplasic dwarf mare he bred from on a regular basis, not having recognised it for what it was.

 

[Marty]

So how about curbing the whole problem by getting these breeders (Who I call GREEDERS) who continue to breed 30-40 and 300 + head a year just to knock it off already? Then you'll all have a whole lot less horses to worry about in the first place.

And my other question is what's going to happen to all the little horses that come up testing positive? Are they going to end up being shoved off to auction or a worse fate taken around back of the barn so someone can claim they are dwarfism free?

I agree with Debby as this is going to cause a world of chaos before it gets better.

 

[rabbitsfizz]

Well, the most they could come up is N/ affected, which means they could be bred to an N/N stallion and, although they could throw another N /affected foal they could never throw a dwarf. That is the very first, baby step.

No horses thrown out/away unless they are dwarfs and there are plenty of people waiting to take dwarfs in, so long as no-one is asking thousands for them!!

Stop all N/A stallions and N/A x N/A breedings.

Plenty of time to get your breeding programme in order......

 

[Mo mhuirnín]

Fools tread where angels fear to go. So here I go.

The only blame to lay is directly at humanities feet. Whether ts HYPP HERDA or Dwarfism humans think more is better so concentrate genetics . There is a saying if one breeds close relatives and get a good offspring its line breeding if it doesn't its in breeding. Crap shoot at whose expense. Right now in my mind some of the horses that are " national show winners" are putting the breed at risk they are getting so fine boned high strung and some of the heads that are analgized to Arabian look like they have an abnormal forhead. For me I will test I will not breed carriers. If its 50% then take that move on for the betterment of the horse.Thank you Mr. Eberth

 

[Lewella]

Over the years I've had the privilege of visiting some of the largest, oldest American Shetland breeding farms in the country during foaling season. Never once have I seen a dwarf foal. Not a one of the old timers I've spoken to over the years has even alluded to their competition producing a dwarf foal and considering how fast they are to out each other on what Hackney or Welsh so and so was rumored to be using behind the barn "back in the day" I feel strongly it is something they would have talked about. Some of our Shetland herds are so tightly bred they'd make an Arabian breeder raise an eyebrow - if dwarfism were there, we'd be seeing it and seeing it often and we aren't seeing it at all.

IMO, it would seriously narrow the miniature horse gene pool to exclude all individuals who test heterozygous for one of the 4 mutations that John identified in his research. If the incidence in a larger sample continues to be at the range it was in his AMHA samples, eliminating the carriers could eliminate such a high number of horses as to make the registry no longer sustainable. Again, just my opinion, but I think dwarfism needs to be approached like SCID, LFS, and CA are in Arabians - test and don't breed carrier to carrier. Over time this will result in fewer carriers being produced. Here is a very good article on breed stewardship in regard to recessive genetic disorders in the Arabian breed - http://www.arabianhorses.org/education/genetic/docs/12Genetic_AHW_Editorial.pdf

 

[rabbitsfizz]

Lewella I am sure that this has come from UK Shetlands, not AmShets. I have seen pictures of some of the animals imported (and there were hundreds, possibly thousands sent out to the states in the late 70's early 80's) and they are straight up dwarfs. I had an enquiry from one of the top studs of the day asking if I had any dwarf foals for sale!! (I told them I did not have dwarfs and if I did I certainly would not be selling them!) I don't think it is a mutation, I think it has been backed up by all the close breeding (call it what you will, it has always worked for me!) and has just gone on circling quietly through the smaller breeds. I have NO idea why anyone would think a dwarf would take the size down, but there you go, Fashion dictates and people follow......

 

[horsehug]

Excellent post and excellent article Lewella. You have explained and look at it the very same way John has explained it all to me for the past 10 years as he did his research and since I first emailed him with questions 10 years ago.

Susan O.

 

[BSharpRanch]

I think that IF the miniature registries would have acknowledged dwarves born to registered stock the whole breed would have been able to make better informed decicions a long time ago. All that they would have to have done is to give the dwarves some type of registration that would NOT allow breeding OR showing. The lines which throw dwarfism would have been known a long time ago, thus breeders would have been able to make better informed breeding choices a long time ago and the cropping up of dwarves, in theory, would have dwindled. Horses that were known to throw dwarves could have had their papers stamped as dwarf carrier, thus making choices easier for all involved.

 

[rabbitsfizz]

I understand what you are saying but it is only fairly recently that dwarfs, of all types, have been fully recognised- and even then sometimes it is very difficult to tell. Even though a dwarf is a dwarf (both copies of the gene) some show minimal characteristics. Perhaps Tremor can be persuaded to put a section of her gallery up?

 

[Tremor]

I think that IF the miniature registries would have acknowledged dwarves born to registered stock the whole breed would have been able to make better informed decicions a long time ago. All that they would have to have done is to give the dwarves some type of registration that would NOT allow breeding OR showing. The lines which throw dwarfism would have been known a long time ago, thus breeders would have been able to make better informed breeding choices a long time ago and the cropping up of dwarves, in theory, would have dwindled. Horses that were known to throw dwarves could have had their papers stamped as dwarf carrier, thus making choices easier for all involved.

It is HARDLY this easy. John Eberth has said before that a large percentage of the miniature horse breed carries at least some type of dwarfism, and almost all lines have been known to produce at least one dwarf.

YES. Let's give the dwarves a registration. For what? To create a market for registered dwarves? Sounds like a horrible idea that would have gone off like wild fire in the 1960s. Crap. Sounds like we already did that.

Rabbitsfizz, anybody specific you would like me to post?

EDIT: I can post pictures of whomever you like tonight when I get off work. Just curious as to what you'd like. Our ex stallion, our mares, dwarf foals, non-dwarf foals, etc.

EDIT: I posted this thread AGES ago and either people don't see it or what, but here's a VERY nice thread with pictures. Take a gander. And to this day, I STAND by my small ear theory. Out of all my horses, all my EXTRA small eared minis have produced a dwarf. That is my theory. I have non-dwarf minis with normal sized ears who haven't produced dwarves (or haven't been bred yet) and some with EXTRA small ears compared to their heads and bodies that HAVE produced dwarves. That's my theory.

http://www.miniaturehorsetalk.com/index.php?showtopic=129033

 

[rabbitsfizz]

I was thinking of the minimal characteristiced proven dwarf producers...

 

[BSharpRanch]

Actually, I have quite a bit of hands on experience with dwarves. IF they had been registered, it would have been just a piece of paper. No show, no breed, just information. By registering them as dwarves ONLY, the most common lines would have been known long before now, however, I assume that when these little anomilies showed up they were probably just disposed of like other breeds did with "unacceptable colors", etc.

I have seen poorly conformed animals all the way to dwarves so dwarfy that you would have to be blind or, well, you couldn't miss them.

So I do have experience with dwarves. Even had a dwarf (shhhh don't tell anyone as they are mystical beings that do not exist) hereford cow. Full sized parents and she was but 30 inches tall at full growth. But ask any hereford breeder and they will tell you that it is impossible as dwarfism was eradicated in their breed!