Dwarf Question.....

[Contessa]

I voted yes. The dam is obviously dwarf and if as you say the sire is a "known dwarf producer" then he carries the dwarf gene. Both sire AND dam need the gene to produce a dwarf. To Manyspots: sorry for your shock but this stallion carries the dwarf gene, you cannot blame the resulting foal on the mare alone. Threads like this are so educational to all of us, glad it was started. As for the little filly, she IS NOT SCUM!(I too would deck the person that said this to you) She is a living creature and although not perfect, she deserves all the love and attention you would would give any other horse.

 

[Molly's Run Minis]

your stallion from just looking at doesn't say dwarf producer to me at all.

if memory serves me right, a horse can easily carry the dwarf gene without looking dwarfy themselves.

it also takes two parents with the gene to produce a dwarf, and lil Conner here certanly looks like a dwarf.

ETA: minimal dwarfs are entirely possible. Quoted from mini-horse.org:

"Equine dwarfism has a complete range of expression from almost-imperceptible (off-bite, short neck) to profound and crippling."

after reading more about dwarfism and looking at pics of your mare and Conner, i think both look like minimal dwarfs.

it looks like Conner's dam's head is longer than her legs and she has a pot belly. Conner has a really short neck with, what looks like, a 'domed' head.

i may be wrong, i'm just saying what i see

 

[Dona]

wow what a shock this AM to see that your stallion is a known dwarf producer! are you sure it is not the mares he has bred previously that are dwarf producers? I knew your sires stallion when Dagnillos owned him and he has some nice offspring out there. And I own the dam, who sired our AMHR National Champion 30 & Under Country Pleasure Driving Stallion. We are waiting for a foal by him now, gotta say this scares the heck out of me. Your dam of the little filly is obviously not a good candidate but your stallion from just looking at doesn't say dwarf producer to me at all. Our stallion is Timberviews Santiago

Just wanted to mention here, that many dwarf producers do NOT show any signs at all, of being a dwarf "carrier". There are known National Champions who are excellent examples of the breed, who have produced dwarfs. So, basically....it can be very difficult to look at a horse & determine whether or not it carries the dwarf gene. Yes, it IS obvioius in some, but definitely not all.

 

[ohmt]

Mollys run- there are different types of dwarfism with different characteristics and varying severity but there is no such thing as a minimal dwarf. It is a made up term and used much too loosely.

 

[Molly's Run Minis]

Mollys run- there are different types of dwarfism with different characteristics and varying severity but there is no such thing as a minimal dwarf. It is a made up term and used much too loosely.

i have to disagree....i think that a dwarf that only has an off bite and a short neck is quite minimal compared to the ones that are on mini-horse.org. thats just my opinon

 

[ohmt]

I have never been to mini-horse.org but I have to question it's validity if it says a horse with a bad bite and short neck is a dwarf. There are 4 types of dwarfism I believe that have been identified and none are characterized by just a bad bite and short neck. Achondroplasia is the most 'minimal' you can get although I suppose that may be depending on perspective.

I wish I could copy and paste on my phone. John Eberth himself is the one who said minimal dwarf was a made up term. A horse either is or isn't a dwarf. It would be more appropriate to say minimal characteristics maybe?

 

[Manyspots]

Dona that is right there have been National Champions producing ,now I am scared. I find Johns study very interesting and really am starting to agree with what I have been told at ISU equine vet clinic. I used to be offended but really think that they are correct in calling our minis, man produced mutants. I didn't like the term mutants, but am leaning toward now after a few years with the minis that they more than likely all carry recessive dwarf genes that will now and then in breedings can click and produce a dwarf. Dona, you are right I have heard others Champ horses produce several nice foals and then a dwarf, or vise versa. They are all special little creatures be they Champions or dwarves and we as breeders need to be aware, anything can and does happen when we tend to play with Mother Nature. Now, back to stall cleaning and some serious thinking......

 

[ohmt]

Ok I figured out how to copy and paste on my phone-yay!

I think everyone who commented on this thread should go to this link: http://www.miniaturehorsetalk.com/index.php?showtopic=86368&pid=926940&st=0entry926940

Look at the description and pictures of the colt and John's response. I think you will all be surprised.

Manyspots-i really don't think all minis are carriers or 25% of them would be dwarf, but there are quite a few. I think now that people are more aware we will cut that down the percentage quite a bit.

 

[rabbitsfizz]

I am on the fence over the "minimal dwarf" thing- I think that it is more than possible that if a horse such as one of mine has three white socks and is a minimal Tobiano, that a horse showing just a few obvious characteristics of dwarfism can validly be called a "minimal Dwarf". As to characteristics, I actually bow to Lil Bits forum on this, they are all dwarf owners and they know what they are speaking about. I know JE is investigating all the genetic side of it (I had thought there were found to be FIVE sorts? but I could be wrong) but I think the info gathered "at the coal face" is also very, very important.

 

[horsehug]

OHMT,

I agree with all you have said (And Dona too). Like I said, I have emailed John about this topic for years and picked his brain and read everything he has written and followed his research.

He still hopoes to have his tests ready as soon as possible! It takes lots of lab work but he is very sure about certain things, like that it takes the gene from both parents to produce one. He is also sure there are some minis that do not carry one, like you said. But a huge number of them do.

And definitely many many minis including lots of champions, that show no signs .......are carriers.

I, for one, am very much looking forward to when the tests are offered. Once we have the tests, we can responsibly and knowingly avoid ever breeding a carrier of a certain type to another carrier of that type, which practice would avoid ever producing a dwarf.

Susan O.

 

[ohmt]

Thanks Susan

I would love to be able to pick John's brain. I volunteer in a lab and help with some gene recombination experiments and there is so much work that goes into the experiments and studies that scientists do so I really appreciate all that John has and is doing. I also can't wait for the tests to come out. That will be a very important day for miniature horses.

 

[Manyspots]

ok I have a question....(remember I was out thinking doing stalls...) How far back can we trace or will John trace on pedigrees that we/he thinks are the dwarf carriers? I got to thinking about the dam of this gals former stallion. She can't be honestly traced back any further even though there is a pedigree listed. When she was purchased it was felt years ago there was a possible mix up on the registration of her and another horse. Nothing strange was noticed until the dam started producing appys! and she herself developed appy characteristics which wouldn't be possible with horses listed on pedigree. Sadly there was another mare similar in color when purchased and the owner had many horses believed a few years later he gave wrong papers with this mare. After I purchased this mare I was told about the mix up but didn't really care as I liked the mare for herself.( hindsight should have just had her papers read unknown) Of course this is an old mare, not producing any more but there are many horses that I am sure are not offspring of who they have listed on their pedigree. Now with DNA we can better know who is producing what. Just curious how many generations back to look? I think doing DNA is the best step forward, ever done. (although I know there are ways around that too. sad)

 

[ohmt]

I believe on one of the threads where people could ask John questions they asked something similar. He was talking grandparents and beyond that said it didn't really matter as the percentages start getting pretty low. That being said, there is still a chance that if a great grandparent or great great grandsire/dam produced a dwarf that it was passed on down the line to the great or great great grandfoal. If a great grandsire/dam produced a dwarf then there's a 50% chance they would pass on a gene to the grandsire/dam then a 50% chance from there to the sire/dam and then another 50% chance to the foal. So that's 1/2^3 or 12.5% chance the foal is a carrier. Of course you have to take into account the percentages from the other side too and that may increase them.

 

[horsehug]

Lavonne,

I am really not sure if he would have any way to do that. You would have to ask John that question.

I know he needed blood from dwarfs for a long time in his research and from their parents if possible, but am not sure if he is beyond that now. I also do not think he would just speculate on anything. And we all know that lots of pedigrees from the past have loads of mistakes on them, some honest mistakes and some that were not.

He is very very busy and I wish so much that I was going to be able to go to his open forum about his research at the Little King Spring sale and seminar April 15 - 17. His Seminar Forum is scheduled to be at 3 pm on Sat April 16 in case anyone gets a chance to go. I sure wish I was closer to Indiana!

Susan O.

 

[ohmt]

Rabbitsfizz-from John's research that he posted on here there had been 4 different types, BUT that was a couple of years ago I believe and they make progress every day so you could be right with the 5. ETA: You are correct! There are 5

In the words of John on the minimal dwarf thing:

First there really is no "minimal dwarf" that has become a slang term for carriers that show alot of characteristics of dwarfism, and for dwarfs that are very "good". If you dont know if the horse is a carrier, are you sure it is just not bad conformation, again some people can be quite wrong sometimes, and most of the time they can be right. This is all subjective right now.
There are normal horses with a recessive gene that might show some expressivity, as I explained in another thread, by Annette. The horse carrying that recessive gene is normal, in a sense. And a dwarf that is a "good" dwarf is not any less of a dwarf than a more severely affected dwarf of the same type, they are both homozygous for the dwarf gene. Again the expressivity manifested itself differently in each one, same as seen in humans.

And here is more that everyone should read that John had posted:

To answer fully your question I need to take into account all 4 possible types I have characterized so far, however there could be more types than these or one of these types could be a combination of two of the four types. Please keep that in mind.Unfortunately, I do not have my reference pictures on a website so I cannot show them here, and they need to stay off of websites for now, until I can definitively state such differences.

The carriers of types 1 and 4 SOMETIMES show subtle features of a type 1 dwarf, i.e. extremely domed forehead, large prominant eyes, very exotic head overall. That being said however, it is NOT 100% true. In the carriers of types 1 and 4, height is extremely variable, bone structure and thickness extremely variable, length of neck extremely variable. I have samples of parents that produce a type 1 dwarf that really do not show signs in the head and are not very small in height, the only give away was pedigree. However other samples give all of the signs, head, off mouth (usually underbite), build, height, and pedigree.

To clarify 1 vs. 4, the type 1 is the type we see most often, the type 4 is the lethal type that does not go to term.

Carriers of types 2 and 3 so far have shown no signs of being carriers, all so far show extreme variation in height and conformation, the only commonality in structure of the parents so far are overall head structure. They are straight, slightly large for body size, very normal looking heads you would see on a regular horse and ARE NOT exotic. But, they are NOT a straight pony head, i.e. what most people refer to in the pony breed. These characteristics are very general visual differences and commonalities I have experienced and documented, and are not conformational facts describing the disease carriers. They are only observations so far that I see as commonalities with conditions producing a dwarf.

Type 2 dwarf is the type that looks like it has a normal body neck and a large plain or straight head, the dwarf just looks like it had it legs cut in half, in reality the upper leg bones are severely shortened, hips miss-shaped, and a large head. These are the bones and structures that I can tell so far are affected, though I do not have enough samples x-rayed and compared to make that definitive. Unfortunately, this is the type I have seen in the past most often used in breeding progams due to the fact that they still have a mostly normal life and reproductive viability.

Type 3 dwarf is the most severe type that is viable, they are extremely small usually, have severe spine (roachback) and leg deformities, usually severely shortened neck, and severely deformed head with off bite. This type is possibly a combination of types, i.e. inheritance of two different recessive dwarf genes due to the fact that the bodies are so severely deformed and variable it has been very difficult to find a consistent deformed type.

There are some concepts I need to explain about the inheritance and expression of recessive genes to qualify my answers. This is especially important involving carriers of recessive dwarf genes and other recessive deleterious genes, and determining, visually, carriers or non carriers and the problems in doing only that.

One concept is PENETRANCE of a recessive gene over a dominant gene in a population. For example how a recessive dwarf gene's characteristics can penetrate and express the condition over the dominant normal gene's characteristics over a large population. Visual example is a normal horse that is a recessive carrier of the type 1 dwarfism and shows some of the characteristics individually or in combinations, like a severely domed head, very large eyes, under bite, etc. The strict genetic definition is "the frequency, under given environmental conditions, with which a specific phenotype is expressed by those individuals with a specific genotype." So you would see variable PENETRANCE of this recessive gene in the Miniature population, which is what I believe is occuring.

Another concept is EXPRESSIVITY of a recessive gene in one animal. The strict definition is the degree to which an expressed gene produces its effects in an organism. So if you take the example of the situation I explained with Penetrance, you have a normal carrier of a type 1 recessive dwarf gene, and it shows some characteristics of possibly being a carrier, well EXPRESSIVITY is the how much effect is the dwarf gene having on the individual horse to overpower the dominant gene, i.e. slang terminology one might hear is "How dwarfy does the horse look?"

Now you also need to understand the difference of these terms and concepts regarding recessive genes when comparing them to co-dominant genes. A co-dominant diseased gene would ALWAYS be expressed in a carrier with its normal counterpart in equal amounts and NEVER be "hidden". A good example in some flowers is the color pink, it is not a one color but a combination of different colored cells, some are red and come are white, making the color look pink with the naked eye.

John has been doing research on this for years and has seen more dwarf horses than probably all of us combined. I trust his findings.

 

[Mona]

Susan (or anyone that knows) have you spoken with John to know why the test is not yet available? The least I remember, was they thought by June of last year, (or maybe even the year before??) I think it was, that they would have the genetic/DNA testing available to test for dwarfism. Whatever happened with that? I have not heard anything since.

 

[horsehug]

OHMT,

I totally trust John's findings also. Thanks for looking up those particular posts on the dwarf forum.

It is loaded with information.

Susan O.

 

[horsehug]

Mona,

I always hesitate to speak for John because I do not want to misquote or get anything wrong.

But the last I heard (and I expect he will expound on this at the Little King Seminar in a couple of weeks) is that while he HAS isolated the genes for 4 of 5 types, he is waiting for the testing process (involving lab work) of ALL 5 to be complete so they can hopefully be offered all at once for testing.

He does not want people to be sending in hair for a couple of tests and then have to send in more etc. It could get pretty expensive and confusing. He wants them all to be offered at once.

Finding enough samples of type 2 originally, and then discovering a 5th type are part of what delayed his original time frame.

And John, if you read this please correct anything I may not have explained correctly.

Susan O.

 

[Mona]

Thanks Susan!! That is sounding so very promising!! Even though I am no raising minis, it has been, and always will be a "dream" of mine to see that testing become available for our breed. It is soooo needed, and I hope John will soon be able to have all the scientific evidence and research needed to complete his mission. GREAT work John, and MANY THANKS to you and everyone that has contributed in any way to make this possible...to make this a REALITY for our breed! YAHOO!!!

 

[Appsolutely]

I have a little filly that was born last Sept. and I know she is probably dwarf, I have not sent in pictures, because I have not been able to get them to go in. But Fiona (my filly) has this terible bite issue with her teeth. She now has 3 teeth in the bottom, but 1 in the top, And the first shock...she was born with them, and shed 2 of the bottom ones when she was about 3 months old.. And yes, she is able to eat, very slow though. She looks dwarf to me, but she may not to others. I had the dentist to come out when she was about 3-4 weeks old and he told me that you never know what to expect in a minis mouth. Neither he nor my vet thought she was a dwarf. She was my first foal. We had minis with my dad, but when he got sick in 2000 we sold them. we had bought this mare bred. So we had no idea. Both parents are registered AMHA. Is there a way to find out if they are dwarf producers? I did not think you could register them, but do I need to somehow do papers on her.I did not breed mom back, guess I was afraid to. Is there a way to find out if she has had other dwarf foals? But my girl has a short, thick neck. And of course,she is a sweet heart. I am sure she is a dwarf, but would like to know for sure. The odd thing is our friends towards the mountains had a foal 2 weeks before us and hers is a dwarf too (No horses related). You can see it more with theirs (tater). But you can tell Fiona is too! So if anyone hears when these test are avaiable, please post. I do not write in much, but I read on here everyday. Thank you so much for the thread and as always thanks for allowing us to learn from you all. I really do learn something everyday I get on here. cindyb