A FOLLOW-UP: Perhaps I'm naiive...

[stormy]

I am always glad to see this topic come up, it is important to the breed but I think we need to try to take some of the emotion out and look at the issue with reason and concern for the consequences of having a test for dwarfism. I have no doubt a test will be developed, the field of genetic testing advancing at an amazing rate.

LWO has been determined acceptable in the breed even though we know crossing LWO to LWO causes lethal white 25% of the time and condemns the foal to a terrible, painful death unless euthanized. Why, because the gene in heterozygous form makes a pretty color pattern.

If dwarfism is a simple dominant we can assure no more dwarfs are ever produced by testing and never breeding a positive to a positive, breed it out over time.

Yet here we have many saying even if it means removing our best horses from the breeding pool any carrier should be eliminated from breeding.

OK so let's look at that:

We reduce the gene pool, likely dramatically...we have other recessives in the breed which would become more prevelent with a reduced gene pool, the eye condition related to silver, off bites, stifle issues, cryptorcid colts, club feet, etc. Is it more important to remove dwarfism completely, instantly than select against theses traits?

What happens to the thousands, maybe 10s of thousands of carriers? Were do they go? What future would they have? And don't come up with something like the breeder should take care of them for the rest of their lives...give some real solutions, something the registry and all involved should be discussing now and preparing for ahead of time.

Why is one defect, LWO accepted and another, Dwarfism not and why should the registry mandate one and not the other? There is no requirement that a miniatures LWO status be provided and every year we hear of unknowing buyers ending up with lethal white foals and the suffering they go through.

Let's try to find reasonable options ahead of time instead of condemning thousands to death or abandonment.

 

[nootka]

We need a test, and personally, worst case scenario and all of my breeding stock (which is small, I admit) were advised against breeding again, I'd cull them.

There is NO horse so great that direct risk of producing that kind of deformity is worth it.

Dwarfs are "cute" to a point, but they are also heart-breaking and repulsive in the same manner. It is NOTHING I would like to see being done intentionally.

To carefully test and breed out the gene would be great, if it becomes possible and the only way to know that is through scientific testing.

People humanize the situation, but the truth is, animals are NOT people although they do have rights and it makes it more complicated when the animals have special needs ( to enforce those rights).

Science is an extremely valuable tool in today's world.

Liz M.

 

[Becky]

It would be absurd to think that there are no genetic defects in miniature horses. It would also be equally absurd to think that chemical pesticides and fertilizers cause no defects either, when they are proven to do so in humans and laboratory animals. Since the majority of horse owners use both, they need to be well aware of the price breeding horses may pay for exposure or ingesting these chemicals. Nothing more, nothing less.

 

[Minimor]

If dwarfism is a simple dominant we can assure no more dwarfs are ever produced by testing and never breeding a positive to a positive, breed it out over time.
Yet here we have many saying even if it means removing our best horses from the breeding pool any carrier should be eliminated from breeding.

Well, you know, with a test then we would all have choices. Those who wish to eliminate all carriers from their breeding pool would have that option.

Those who want to continue using carriers as long as they breed them to non-carriers, they would also have that option. Those people, though, would have to accept the fact that a certain number of buyers would want to buy only those foals that test negative for the dwarf gene. Those breeders would then have to figure out what to do about the carriers that they raise. Perhaps they could find enough buyers that are willing to purchase carriers. If not, then perhaps they would have to rethink their breeding program to make sure that they don't continue to produce carriers. I have no idea how that would work out, if there would be many such buyers or not.

Many are saying that they see nothing wrong with continuing to breed carriers to non-carriers....to those that have that belief, if you were buying more horses would you be willing to purchase carriers, and if so would you pay top dollar for one of those carriers, or would you expect to buy at a reduced rate?

 

[Charlotte]

Playing devils advocate here. What if.........it is found that the genetics for dwarfism are carried by all miniature horses? That is assuming that tests can ever be developed for the various types of deformaties we lump under the term 'dwarf'. These abnormalities had to come from somewhere. We have all heard of the occasional 'dwarf' born in large horse breeds so the genetics must be 'out there'. Are they out there everywhere? So then as miniature breeders, what would be our game plan to minimize the effect of these genes on our breed?

Careful selection of breeding animals? What other plan?

I for one will be SO glad if/when tests can be developed for dwarfism so that we can know with reasonable certainty whether we are looking at genetic abnormalities or enviornmental factors causing deformaties. We have COMPLETELY stopped fertilizing our pasture and paddocks after the reports of the Canadian standardbred breeding farm's high deformity rate of a few years back. Thank goodness they found the cause and published the information. And we no longer plant any of the types of forage which bind nitrates under certain weather conditions. (I've become paranoid about forages to the point of having our pastures tested for nitrates) I'm sure there are many things besides nitrate levels which can cause problems in breeding animals so I hope when those problems arise the information will be published somewhere.

So what ideas come to mind if a genetic problem is universal?

Charlotte

 

[wildoak]

my understanding is there could be different genes responsible for the different types of dwafism (please correct me if I'm wrong). John is working on one type only. I'm going to throw this out for debate - what if the 'gene' proves to be highly prevalent as in over 50-80% of minis (unrelated lines) carry this gene? Do we eliminate all those horses or do we work at managing the risk and/or slowly eliminating it over time?

I think Michelle hit the nail on the head, as well as Charlotte playing devils advocate

Absolutely, it will be a huge step forward to have a test for dwarfism. But it may take multiple tests to determine different expressions of dwarfism, something a good bit more complicated - and much further down the road, I would suspect. If I remember correctly some of what John said, it may well be represented in quite a few prominent bloodlines - bloodlines that have strengths in many areas. Time will tell, but as of now I'm inclined to believe that culling dwarfism from our horses will be a lengthy process that will span more than a few generations.

If the test becomes available, I will absolutely test my breeding horses. What I do with those results will depend on what we know by that time as to the prevalence of the gene.

Jan

 

[disneyhorse]

If dwarfism is "said" to be caused by environmental issues... why aren't ALL other horse breeds so widely affected? Wouldn't you see dwarfs in every other breed? A horse is a horse. I firmly believe that 99.9% of dwarfism is genetic. And I believe the genetics can be "figured out" eventually... look how far human genetics have been "figured out" in recent years...

Andrea

 

[Charlotte]

Andrea, I think you miss the point I and others have made. 'Dwarfism' may have only a genetic basis. However, there may be many abnormalities which are similar to genetic abnormalities in appearance, but have a cause other than genetic. Read the reports on the Standardbred abnormalities cuased by high nitrate in early gestation in Canada. the description of the deformaties, if we saw them in a miniature horse foal, we would say 'dwarf' because we miniature owners have been so programed to respond that way without thinking the whole scenario out.

Untill we have genetic identification for dwarfism we need to really use our heads when trying to understand where a particular abnormal animal might have come from. Such as, say, a stallion siring 3 out of 9 or 10 'dwarf' foals in a year. By the laws of genetics, this would be statistically highly unlikely. So the wise breeder is going to keep an open mind and investigate other possible explanations.

As to why other horse breeds aren't as widely affected as the miniature breed by either genetic dwarfism or enviornmentally caused abnormalities, I sure don't have an answer for that. I might ask why my miniature stallions have both almost died from being administered a commonly used laxative to treat impaction colic. a laxative used all the time with large horse breeds and administered in the correct dosage by some of the best equine practitioners in this country. Why did they have such an adverse response? My answer...they are horses, but they are miniatures and may respond differently to their enviornment.

Open minds will eventually find the answers we seek. (or at least I like to think so)

Charlotte

 

[Minimor]

Charlotte, I have SEEN those horses here in Canada. I have talked to Canada's leading researcher of this problem, and I specifically asked him about all these similarities to dwarfism. There are few similarities!! Yes, these horses do often have an underbite, but that is pretty much the only similarity to dwarfism.

The horses you refer to have leg deformities, but they are not the same deformities as you find in dwarfism. The leg deformities caused by congenital hypothyroidism (which is the issue you are referring to) consist of weak extensor tendons and under developed knee and hock joints. These horses do not have the shortened, twisted legs of a dwarf.

I specifically asked this researcher about those deformities, and described the dwarfism deformities I was referring to. He said no, that is not what he has seen in any of these horses. He said the under developed joints and weak tendons...which can be so severe that the foal cannot stand...may be referred to as deformities, but those are the only "deformities" he has seen in these horses. Having seen this condition in my own Morgans a number of years ago I can tell you that the affected foals looked nothing like dwarves.

We had Mini foals affected by this same condition in 2004, as did another breeder here in this area. None of the affected Mini foals resembled dwarves in any way. Their issues matched those of congenital hypothyroidism but there wasn't a one of them that in any way resembled a dwarf.

Certainly environmental factors can cause problems in foals, but congenital hypothyroidism/nitrate poisoning is unlikely to resemble dwarfism. It may cause underbite, but in all other respects it is quite different from dwarfism. John's posts on the dwarf forum confirm what I am saying.

 

[bingo]

. Such as, say, a stallion siring 3 out of 9 or 10 'dwarf' foals in a year. By the laws of genetics, this would be statistically highly unlikely.

I am sorry I have to respectfully disagree. I do not find it unlikely at all especially given all the defenses and excuses that many mini breeders give to continue to breed what they have in their herd and is known to be a carrier of dwarf genes by the history. So many continue to justify why it is perfectly acceptable to continue breeding them that I do not see 3 out of 10 dwarf foals at all unlikely given the laws of genetics.

I do believe Disneyhorse has a very valid point. Why is it that you do not see these supposed environmental issues so prevalent in QH, APHA, TB, Walkers, Morgans, Arabs or any other of the hundreds of breeds? Well I think the answer is simply mini breeders tend to defend and justify why it is ok to continue with the programs they have. JMHO

 

[nootka]

Yep, I'm pretty sure we'll find out that dwarfism is mostly genetic in miniatures. Otherwise, as pointed out, it would be more prevalent in breeds that are more popular and more numerous.

I could be wrong, but I also think it's easy to say it's something else when we fail to recognize that striving for the tiniest miniature and ignoring conformation (look at the HUGE heads on some of these "tinies" I have seen a rare few that are under 28" that don't have gargantuan heads and thick, thick bones for their actual height) have led us into a problem where there is a fairly high rate of dwarfism.

No, it's not all the smallest of them that have it, but smallness is a symptom of dwarfism and if you ask me (look through the Mini horse publications of the late 70s/early 80s and I think you'll agree), the problematic conformation was overlooked in lieu of bragging rights of "smallest."

They're cute, but they're also not right, and it's wrong to breed specifically for them.

I think that what will be painful is those that are looking for other excuses to explain away their blindered view of breeding when they've been selling their horses banking on the smallness. yes, they may win titles, but look at the competition.

We can speculate all day long, and opine til the sun goes down (myself included), but we need some cold, hard, scientific fact to help guide us. Even if it's just one type of dwarfism, it's a beginning, and I'm all for it.

I'd love to have the ability to determine the probability of a dwarf birth. For now, i'm rolling the dice with the ones that I can reasonably suspect have little chance of throwing a dwarf (note that I did not say NO chance, I am nowhere near that arrogant).

Liz

 

[Michelle@wescofarms]

I think the point Charlotte (Sorry I'm speaking for her!) was trying to make was congenital hypothyrodism in someone unfamiliar with this would class a foal being a dwarf (Underbith/crooked legs), not knowing of this condition. We're better educated than we were even a few years ago, but honestly there are people that still don't see a dwarf when its sitting in their barn! So, lots of room for education and understanding.

As for the point Liz has about the huge heads/heavy bones - ask some of the long time breeders trying to reduce a mini in size. Things do not shrink the same. Heads and teeth are one that doesn't reduce down in a generation from my understanding. So is that a dwarf, or just something in attempting to a achieve a well proportioned small horse will require selective breeding? In discussions with breeders they've told me getting the teeth to shrink in size is a goal - smaller teeth=correct bite= smaller head.

The heavy bone I still don't get but was told it's just that heavy bone not necessarily a dwarf sign. So??? Not something I want to breed for that's for sure.

I do believe that testing will prove the majority of dwarves are genetic. How prevalent . . . that will be interesting. Seriously as Charlotte mentioned what if its highly prevalent? What if the Top Tens from both halter/driving in both registries for the past 10 years are carriers? What if that great topline we love goes hand in hand, or the dishy head or wonderful neck set or large eyes?

I also believe malformations/major flaws can be environmental or dietary or age related as they are in other animals - and these could be classed (by uneducated or undereducated people) as a dwarf. I had a c-secion on a mare this year as the foal was dead and 45 minutes of the repro team trying to reposition it while she was sedated - it was a no go. I asked for photos of the fetus (the vet didn't take them or didn't give them to me - still not certain on that), but the foal was delivered very dead but with all its intestines born on the outside of its body - no other issues from what the vets told me. Now that isn't a dwarfism sign - so was it a bad genetic cross, or ?? And UCD told me they've had this occur in all size breeds of horses - some even born alive that have to be put down. But someone not very into research or the science of breeding might do who knows with this information.

What's the cause? They had no idea nor do I. Will I repeat the breeding - definitely not on the off chance it was genetic in nature. Unfortunately as John mentioned the genome project may be done but now its what to do with that information. Horses are not highly funded as there isn't the monetary incentive as there is with cattle/sheep/hogs, etc.

I think we all need to understand the members of the Forum are - I believe at least - better informed and truly want to do well in breeding, showing or raising Minis. Why I'm glad that we can have sensible debates as I do like to hear others opinions, research, and experiences. BUT that does not account for the vast majority of people with Minis out there that either don't or won't care or are just to plain ignorant to want to care.

If you want one of the cosmic jokes - go research sickle cell anemia and maleria in humans and figure that genetic trade off!!! Sickle Cell Anemia