All this talk about dwarfs

[Sue_C.]

I believe in the end it will not be as simple as getting rid of all known carriers

There would be no need to "get rid of" known carriers, if one opted to take the chance to breed them, if one was religious about culling their herds, should those carriers, when bred to non-carriers, pass it on. I am one who would not breed a carrier, but that would be my personal decision.

I do not beleive that all Miniature Horses carry this gene. I also beleive it is very possible that many of the blood-lines that started out using dwarves, might very well have branches with a clean gene pool by now.

That is what will carry the breed into the Future...those family trees, KNOWN not to be carriers, of the most common, inheritable forms of dwarfism, at least. We can only hope...and do the best for the breed, as we see fit.

 

[horsehug]

There are lots of posts on the subject of dwarfism if you do a search on the forum for it, but I thought this one was very very good, and worth reposting from earlier this year, with all the newcomers daily to the forum, and especially since John Eberth has done and continues to do most of the research into finding a test for dwarfism.

Here is the link to the thread on the perspective of Little King Farm.

http://minihorse.ipbhost.com/index.php?showtopic=51169&hl

Susan O.

 

[Little Bit]

Come to find out this stallion was full blooded brother to this mare. So the dwarf this mare had was not her fault and I hate to say it but it falls on the fault of that specific breeder.
Thank God we all do not breed this way.

I know sometimes it happens, and we do not have control over that but hopefully we learn from it.

She has since had the stallion gelded and took the mare to have bred to another stallion I found for her. We both felt this mare deserved to have one healthy, beautiful foal.

Yes, the fault of this dwarf foal falls on the breeder who bred a full brother and a sister together, however the mare is most likely carrying the dwarf gene, and yes, she may have a beautiful, normal looking foal, but chances are the foal will also be a carrier.

With the information that we have now, we HAVE to assume that the mare and the stallion that produce a dwarf foal ARE both carriers of the dwarf gene, until it can be proven otherwise.... I suppose people can rationalize it to the point where they can feel good about breeding known dwarf producing animals, but I could not. :no: JMO

I don't breed any of my mares. 10 years ago I just had to have a mini foal of my very own, and I got VERY lucky, the foal was not a dwarf. Her and her Momma still live together, and yes, I suppose you could say they are pasture ornaments, however, I get a lot of enjoyment out of them as pasture ornaments, with no feelings of needing to breed them what so ever.

 

[Little Bit]

I believe in the end it will not be as simple as getting rid of all known carriers.................actually I am convinced if that were done the miniature horse as we now know it would not exist. I am not looking for arguments as we can argue amongst ourselves ad nauseum (and have many times ) and still end up right where we started nowhere with just as many unanswered questions as before.

With the information we have right now, I feel that taking the known dwarf producing horses out of the breeding programs, is the ONLY way we can hope to reduce the number of dwarf foals being born!

And with the number of Miniature Horses in the U.S. I really doubt that if every known dwarf producing horse was taken out of the breeding programs, that the M.H. as we know it today would not exist. It's not like we are dealing with a limited number of horses, like they are in other countries! And it certainly wouldn't hurt to have fewer Miniature Horses born for few years anyway, especially as I mentioned earlier that I feel the market has been saturated for several years now, and that there are MANY Miniature Horses ending up in auctions and slaughter houses.

JMO

 

[Little Bit]

This is a direct quote from an article that John Eberth wrote, it is on page 4 of this website along with the article that I wrote a few years back, if anyone is interested in reading them:

http://www.angelfire.com/ms3/dmh/

To begin I will start with what is known that is 100% true and scientifically accurate and correct.

There are many different phenotypes of dwarfism, which means there are many different types of dwarfs that have different problems and physical abnormalities.

That being said, there are obviously many different mutations in different genes causing these different dwarf types.

With that you need to consider which type(s) is/are the most prevalent and each sample of each type being identical in its abnormalities to be consistent in it phenotype.

OK, now the most prevalent type I have seen and documented is a type that is very similar to cattle dwarfism, which shows symptoms and phenotypes consistent with a human type of dwarfism called achondroplasia. This type of dwarfism in humans by chance (or maybe not) is also the most prevalent type of dwarfism in humans as well.

Now in order to be an achondroplasic dwarf in humans you must have one parent that is an achondroplasic dwarf or be an achondroplasic person born by two normal parents from a spontaneous mutation in a bone growth gene, I will spare you the specifics, but this type of dwarfism is called a dominant genotype, which means that if you have even only one copy of the gene you show the disease, so a human with Dd heterozygous genotype is a dwarf, dd is a normal person, and DD is a homozygous genotype dwarf, which is worse than Dd.

Now for miniature horses it is different, a dwarf of achondroplasic characteristics, is born to two parents that look like normal horses. This is what is called a recessive genotype, which means you can have the mutated gene and not show the disease. This means that a horse that looks normal can carry a mutated gene recessively and not show the disease characteristics, or phenotype. So, in order for a dwarf to be born, both horses, sire AND dam MUST carry the gene to produce a dwarf. THIS IS A FACT for a recessive disease gene to show its phenotype, both the sire and dam are carriers of the diseased gene, and BOTH passed their copy of that diseased gene to the foal that shows the phenotype of the disease. So it takes both the sire and dam to make a dwarf.

 

[runamuk]

I believe in the end it will not be as simple as getting rid of all known carriers.................actually I am convinced if that were done the miniature horse as we now know it would not exist. I am not looking for arguments as we can argue amongst ourselves ad nauseum (and have many times ) and still end up right where we started nowhere with just as many unanswered questions as before.

With the information we have right now, I feel that taking the known dwarf producing horses out of the breeding programs, is the ONLY way we can hope to reduce the number of dwarf foals being born!

And with the number of Miniature Horses in the U.S. I really doubt that if every known dwarf producing horse was taken out of the breeding programs, that the M.H. as we know it today would not exist. It's not like we are dealing with a limited number of horses, like they are in other countries! And it certainly wouldn't hurt to have fewer Miniature Horses born for few years anyway, especially as I mentioned earlier that I feel the market has been saturated for several years now, and that there are MANY Miniature Horses ending up in auctions and slaughter houses.

JMO

I ask what information do we have that would lead you to draw this conclusion? We don't even know how many forms of dwarfism are in miniatures. I have slowly changed my mind on this subject after indepth research and many private discussions with some of the geneticists actually studying this and trying to find the gene or genes responsible. The other problem with the don't use known carriers is you are potentially losing very valuable breed characteristics. The problem is we don't have any substantiated information in miniatures. In other species the dwarf gene is accepted and vital to breed characteristics..........think pug, bulldog, doxies, corgies, bassets, in cats you have manx who sported the begining of the munchkin breed.........rabbits netherland dwarf, jersey woolies, dwarf hotot.......it isn't as simple as not breeding known carriers even when they can be identified which at this juncture they cant we can only assume. What makes more sense is to not use horses who have obvious unwanted characteristics such as shortened appendages, long backs, excessive sized joints and coarse bone, bad bites, all of which may or may not be associated with dwarfism.

 

[runamuk]

This is a direct quote from an article that John Eberth wrote, it is on page 4 of this website along with the article that I wrote a few years back, if anyone is interested in reading them:

http://www.angelfire.com/ms3/dmh/

To begin I will start with what is known that is 100% true and scientifically accurate and correct.

There are many different phenotypes of dwarfism, which means there are many different types of dwarfs that have different problems and physical abnormalities.

That being said, there are obviously many different mutations in different genes causing these different dwarf types.

With that you need to consider which type(s) is/are the most prevalent and each sample of each type being identical in its abnormalities to be consistent in it phenotype.

OK, now the most prevalent type I have seen and documented is a type that is very similar to cattle dwarfism, which shows symptoms and phenotypes consistent with a human type of dwarfism called achondroplasia. This type of dwarfism in humans by chance (or maybe not) is also the most prevalent type of dwarfism in humans as well.

Now in order to be an achondroplasic dwarf in humans you must have one parent that is an achondroplasic dwarf or be an achondroplasic person born by two normal parents from a spontaneous mutation in a bone growth gene, I will spare you the specifics, but this type of dwarfism is called a dominant genotype, which means that if you have even only one copy of the gene you show the disease, so a human with Dd heterozygous genotype is a dwarf, dd is a normal person, and DD is a homozygous genotype dwarf, which is worse than Dd.

Now for miniature horses it is different, a dwarf of achondroplasic characteristics, is born to two parents that look like normal horses. This is what is called a recessive genotype, which means you can have the mutated gene and not show the disease. This means that a horse that looks normal can carry a mutated gene recessively and not show the disease characteristics, or phenotype. So, in order for a dwarf to be born, both horses, sire AND dam MUST carry the gene to produce a dwarf. THIS IS A FACT for a recessive disease gene to show its phenotype, both the sire and dam are carriers of the diseased gene, and BOTH passed their copy of that diseased gene to the foal that shows the phenotype of the disease. So it takes both the sire and dam to make a dwarf.

This is basic genetics however the assumption being made is that the horses LOOK normal well in all honesty miniature horses in general based only on size fit the dwarf mold........in humans 4'9" and under is considered dwarfed...........so it depends on what we are considering normal looking. The idea of a reccessive gene is based on a percentage of dwarf foals born to "normal" and total population......this is a guess at best as many many people still produce dwarves and never does anyone hear or know that it happened they are quietly and discreetly dealt with. Not to mention the questionable dwarves (those less obvious but the herd sire of a high producing farm or small breeder) that may not be considered in the equation................................this is where the money and dna samples are needed the more known dwarves that can be sampled the sooner the gene/genes can be discovered.... so the people who are dealing with their dwarves behind the barn really need to at a minimum step up and get dna samples to the appropriate researchers.

I still think education on what is proper equine conformation is more likely to reduce the incidence of dwarves than simply not breeding known carriers. Think about it for a minute there are some very good quality stallions who have contributed major improvement to the breed do you quit breeding them just because they produced one dwarf? 1 dwarf vs 10 or 15 top notch stallions continuing to improve the breed...........too bad there isn't a cure for barn blind

:

: just cuz it is intact and small does not mean it "should" be bred.

 

[WSR's_Judy]

In the case with my sister's mare, because the mare and stallion was full blooded maybe I was wrong in calling it a dwarf, maybe it had birth defects from being line bred to closely related.

After my posting I called my vet and talked with him about dwarfism.

He said " that sometimes dwarfism is labeled to horses and people that actually have some form of birth defect or sometimes things go wrong while the mare was pregnant. Like she gets kicked by another mare or the falls for some reason and because of the position of the foal, the foal is born with a bad bite or leg. He said that sometimes people are to quick to judge, do what ever testing can be done to make sure that it is not a genetic problem before a you label a mare or stallion as carrying a dwarf gene. Yes there is some problems that horses can have that you know is genetic like legs correctness, but does not mean that its related to dwarfism, maybe the two horses genes just was not compatible."

So after talking with him it brings to question are we judging our little horses to quickly before we completely have all the tests. We may have some genetically correct horses that had a bad occasion during pregnancy but because their foal turned out less than perfect we label it dwarf.

 

[RJRMINIS]

In the case with my sister's mare, because the mare and stallion was full blooded maybe I was wrong in calling it a dwarf, maybe it had birth defects from being line bred to closely related.

After my posting I called my vet and talked with him about dwarfism.

He said " that sometimes dwarfism is labeled to horses and people that actually have some form of birth defect or sometimes things go wrong while the mare was pregnant. Like she gets kicked by another mare or the falls for some reason and because of the position of the foal, the foal is born with a bad bite or leg. He said that sometimes people are to quick to judge, do what ever testing can be done to make sure that it is not a genetic problem before a you label a mare or stallion as carrying a dwarf gene. Yes there is some problems that horses can have that you know is genetic like legs correctness, but does not mean that its related to dwarfism, maybe the two horses genes just was not compatible."

So after talking with him it brings to question are we judging our little horses to quickly before we completely have all the tests. We may have some genetically correct horses that had a bad occasion during pregnancy but because their foal turned out less than perfect we label it dwarf.

Well I wander the same, as my mare just aborted a deformed foal that the first thing I thought was a dwarf, and that is what everyone that see's it says too.

BUT when my vet removed it from her, I said OMG it looks like a dwarf.........he said it was severly deformed and we are not sure why, it could have been something the mare was exposed to, or alot of things can cause malformations.

Ok, so I have to wander, since she has had two healthy correct foals, am I being to quick to judge her and the stallion she was bred to, First thing I said was she would never be bred back to him, if I even breed her again.

I sure wish there was a test, so you would know for sure.

 

[kaykay]

for the record kscowgirl i dont think your aborted foal was dwarf at all and I dont think the similiar one tony had was either. they look more like a severe mutation. Dont forget that environmental factors can also wreck havoc with reproduction. toxins in the pasture etc can produce damaged foals

 

[Little Bit]

.......it isn't as simple as not breeding known carriers even when they can be identified which at this juncture they cant we can only assume. What makes more sense is to not use horses who have obvious unwanted characteristics such as shortened appendages, long backs, excessive sized joints and coarse bone, bad bites, all of which may or may not be associated with dwarfism.

I didn't add that horses with obvious unwanted characteristics should also NOT be bred, because I guess I just assumed that this was a given.

All the characteristics that you mentioned are dwarf characteristics, and like you mentioned, a perfectly normal horse can have some of these characteristics and certainly NOT be a dwarf, as there a LOT of pet quality horses out there with bad bites and crooked legs, but that certainly doesn't make them a dwarf.

I still think education on what is proper equine conformation is more likely to reduce the incidence of dwarves than simply not breeding known carriers. Think about it for a minute there are some very good quality stallions who have contributed major improvement to the breed do you quit breeding them just because they produced one dwarf? 1 dwarf vs 10 or 15 top notch stallions continuing to improve the breed...........

I feel that BOTH education AND not breeding known dwarf carriers, is what is needed to reduce the number of dwarf foals being born, and threads like this one will hopefully help with both things.

And YES, in my opinion once a stallion or mare produces a dwarf foal, it should be pulled from the breeding program. I don't care if it had produced 15 or 50 good quality foals.... just how many of those foals do you suppose he/she passed the dwarf gene on to? He/she has now proven him/herself as a carrier of the dwarf gene, and he/she has passed it on to enough foals!