DWARFS

Dwarf Miniature Horses

A Very BIG Thankyou to Janell Jensen for letting the IMHR
Use her information and pictures of her
Special Little Horses

Dwarfism in the Miniature Horse
By Janell Jensen
In order to lessen the chances of producing dwarves, or eradicate the
risk all together, we need to learn all we can about them as well as
find a way to test for the gene that causes it. Since it is such a prevalent problem
in our breed, I feel that sharing what we know and learn is the first
major step in this process, which can only be good for the breed as a whole.
I also believe that all dwarves should be registered (as dwarves)so that there can
be a record of their births. I think that is the only way we are going to be able to
lessen the chances of producing a dwarf. We need to be more selective in our
breeding as well, by not breeding any horses that have any dwarf characteristics at all,
and seriously thinking of gelding a stallion that has produced a dwarf foal, and
taking a mare out of you breeding program is she has produced a dwarf foal.
By taking the mare out of your breeding program, I mean that she should not
be sold to someone else for their breeding program either, only as a pet.
My goal with this paper is to educate the general public as well as the Miniature Horse industry as a whole.

I am unaware of any actual scientific studies to prove or disprove the
existence of a dwarf gene and how it is passed on. Nevertheless, it used to
be believed that only the stallion carried the dwarf gene, but now it is believed that
both the stallion and the mare can carry the dwarf gene.The dwarf gene is a recessive
gene and it takes 2 parents having the recessive gene to produce a dwarf foal.
So once a mare & a stallion have produced a dwarf foal you KNOW that they
both have to be carriers of the recessive gene. Breeding these two
horses together again will give you a 75% chance of them either producing a dwarf
foal or producing a normal foal that is carring the recessive gene. NOT GOOD!
There is a 25% chance that these two horses will have a dwarf foal, a 50% chance
that they will produce a normal foal that is a carrier of the dwarf gene and
only a 25% chance that they will produce a foal without the
recessive gene..... NOT GOOD ODDS EITHER! So anyone who breeds known dwarf
producing horses only have a 25% chance of producing a foal that
is not a dwarf or a foal who is not a carrier of the
dwarf gene... DEFINETLY NOT GOOD ODDS, if ya ask me!!!!
I also believe that there are MANY more dwarves being born each year
than most people want to believe or will admit to.

Best case scenario (if the unknown horse is not a carrier): 50% chance of
producing a carrier, 50% chance of producing a normal horse (not a carrier).

If the unknown horse is a carrier as well: 25% chance of producing a dwarf,
50% chance of producing a carrier, and 25% chance of producing a completely
normal horse (not a dwarf and not carriying the dwarf gene)

The life expectancy of a dwarf is not nearly as long as a normal miniature horse.
It depends on the severity of the horse’s dwarf characteristics.
These special little horses are never with us nearly long enough!
Yes, a horse CAN be a little dwarfy, unlike being a little pregnant!
There are many degrees of dwarfism and many different types of dwarves.
Dwarf characteristics will be passed on through the genetics into their offspring,
whether the genes manifest themselves in this generation or not,
they now reside in the horse’s DNA and will crop up, be it now or later.
What is fascinating is that coiled inside an animal’s DNA are
secrets about its heritage as well as its progeny.

In the August/September 1998 issue of Miniature Horse World,
dwarfism is described as the following:
Dwarfism n. — underdevelopment of the body, characterized
primarily by abnormally short stature, often with underdeveloped limbs and other defects.
Causes include genetic defects, pituitary or thyroid malfunctioning,
kidney disease and certain other disorders. (Rothenburg and Chapman 1989)

The structural anomalies of dwarfism in horses are essentially
the same as they are in humans. The most common type of dwarfism is the
brachycephalic dwarf (brachy = shortness, cephal = an association with the head),
whose middle third portion of the head, namely the nasal bridge, is
characteristically low and flat. In addition, characteristic of the Brachycephalic
dwarf are enlarged joints, a short neck, and excessively short limbs.

Achondroplasia, on the other hand, is an inherited disorder in which a
defect in cartilage and bone formation results in a form of dwarfism
characterized by short limbs on a normal trunk. (Rothenburg and Chapman 1989)

Some horses show vague characteristics, which are difficult to discern.
Some show dwarf characteristics and are not full dwarfs; they can live
a relatively full life, but often begin to suffer from some type of joint
degeneration after reaching maturity. Others begin their lives looking almost
completely normal and begin to change as they mature. Still others have such
severe manifestations that the animal has to be euthanized.

Some common phenotypic characteristics of Dwarfism in the Miniature Horse Breed:
1. Achondroplasia—(legs do not grow in length). Normal bone growth does not occur
and often develops unevenly at the joints, causing crooked legs.

2. Dwarf foals are sometimes born with contracted tendons or tendon
laxity. Joint enlargements and joint deviations are common,
often becoming progressively serious with age. Extreme cow hocks, extremely
short gaskins and sever sickle hocks all with varying degree of joint
laxity and /or joint weakness are also common. Premature Arthritis is common as well.

3. Some types of dwarfs have an over bite, or an under bite.
If an undershot jaw is present, the molars may also be out of alignment,
requiring that the teeth be floated more frequently than for a horse with a normal mouth.
Highly placed nostrils always accompany the undershot jaw.

4. Brachycephalic dwarfs have a large buldging forehead
with an extreme dished face, overly large eyes (sometimes placed at uneven angles)
and nostrils placed too high up on the face.
A second type of dwarf has a more normally shaped head and eye and longer neck,
but its head and body are still oversized when compared to the length of its legs.
This second type of dwarf does not usually have an undershot jaw.

5. Head obviously longer than the neck. In some dystrophic dwarfs, the
neck appears to come directly out of the shoulders.

6. Girth depth is greater than the leg length. Disproportionately
oversized entrails and genitals. That is why so many dwarfs have the big “pot bellies.”

7. Vertebra deviations are common.

8. Often unable to rear or stand on hind legs. Some types have an odd “
tilting backward” gait with shoulder higher than the croup.

9. Sometimes associated with the various dwarfism syndromes are less
obvious characteristics such as mental retardation, heart and other internal
organ defects, sterility, shortened life span, arthritis and inactivity or depression
(both of which are probably due to pain).

There are over 200 variations of dwarfism characteristics that
have been cataloged and well described in humans alone. In the dwarfed
miniature horse, most of these characteristics are recessively inherited
(both the sire and the dam appear to have normal conformation).

QUESTION:

In a nutshell, how would you describe the 4 types of dwarfs as outlined by John Eberth?

I'm not sure anything about dwarfism in the Miniature Horse can fit into a "nutshell"!
To me John's discription of Type 1 is a bit confusing, as he writes:The carriers
of type 1 and sometimes
4 show subtle features of a type 1 dwarf, i.e. extremely domed forehead,
large prominant eyes, very exoctic head over all.
That being said however, it is NOT 100% true. In the carriers of type 1 and 4,
height is extememely variable, bone structure and thickness extremely variable,
length of neck extremely variable." John says," type 1 is the type of dwarf we see most often."

So if I am understanding this right, perhaps my Tessa would be a
type 1 dwarf, as she is taller than most dwarves, her neck is longer than a lot of dwarves,
but she does not have an extremely domed forehead Tessa's,
dwarf characteristics are not nearly as severe as Little Bit's was.
Here is a picture of Tessa at age 10 years old.


She was 12 in this picture and is about 28 inches tall.

  

She was 2 years old in this pic


A close up of her head, her bite is not off very much at all

Perhaps Inky and Smidgen are also type 1 dwarves, as they
remind me a lot of Tessa, except that they are MUCH shorter.
Smidgen at age 3 and 23 inches tall

Inky at age 4 and 24 inches tall

John writes:
The 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's legs cut in half,
in reality, the upper leg bones are severely shortened(forearms & gaskins),
hips miss-shaped, and a large head.
The Type 2 dwarf is what we have referred to, for many years,
as an "Achondroplasia" type dwarf.

My Toy is this type of dwarf.
Toy was 12 hours old.

Toy at about a year old

Toy at 3 years old and
about 26 inches tall

Toy's bite at 2 years of age

Now at age 3 years, she does have a slight underbite.
Other things I have seen in the type 2 dwarf, is that they all
have VERY cow-hocked back legs, tiny ears (in comparrison to their head),
and their bites are not off by much and sometimes right on and many
times they have contracted tendons in their front legs, and many times it
is just their right front leg, like you see with my Toy.
I also believe that their bodies are MUCH longer than a horse with correct conformation.

John writes this about the type 3 dwarf:
It is the most severe type that is viable, they are extremely
small usually, have severe spine (roach back) and leg deformities,
usually severely shortened neck and severely deformed head with and off bite.
This type is possibly a combination of types, i.e. inheritance of two recessive
dwarf genes due to the fact that the bodies are so severely deformed
and variable it has been difficult to find a consistant deformed type.
This Type 3 dwarf is what we have referred to for years, as a "Brachycephalic" type dwarf.

I believe that my Little Bit was a Type 3 dwarf, and so is my Strawberry Delight.
Little Bit at 2 weeks of age

Little Bit at 8 months old

Little Bit at 2 years of age, he was 20 inches tall at age 3 when he passed away.
I have seen many dwarves of this type that also, could not put their
tounges all the way back into their mouth. They almost always have tendon
laxity in at least one leg and it's usually in all 4 legs at birth.
These horses must have their legs braced or wear corrective glue on shoes,
like my *Little Bit's *Magic Shoes*, in order for them to stand up
on their hooves correctly. The bracing should only be temporary until
some corrective shoes can be applied to their hooves, as the bracing
will keep the horse from stretching those tendons even more, but it also
keeps the horse's legs from getting strong enough to hold up their weight.
The shoes allow this to happen. Many times this type of dwarf
has respiratory problems, heart problems and digestive problems, as well.
This type of dwarf almost always has a very bad bite, either an
over bite or under bite, but most always an under bite
I believe the life expentency of this type of dwarf is MUCH shorter than the 1 or 2 types.

Strawberry's head as a 5 year old

Strawberry at age 5 and 25-26 inches tall

John writes this about Type 4 dwarf:
Growth--extrememly small stature
Craniofacial--Cranium large for gestation age, low nasal bridge, micromelia
Limbs--severe lmicromelia
Bones poorly ossified for gestation stage, ribs extremely short and thin
Lethal recessive
Mutation is in gene for diastrophic dysplasia which codes for a sulfate transporter DTDST

Type 4 dwarf does not go to term

My equine dentist, Carl Mitz, was telling me that John Eberth was
thinking that this type of dwarf was new on the scene, but Carl said that he
has seen this type of dwarf MANY years ago, so it is not something new, in his opinion.
As far as "minimal dwarves" go, I agree with John, there is no such
thing as a "minimal" dwarf....a particular horse may have a lesser
degree of dwarfism than some, but that does not make it any less of a dwarf.
So some folks like to refere to these dwarves with a lesser degree of dwarfism,
as "minimally expressed" dwarves, in other words their dwarfism is not esxpressed as much as other dwarves.

I think there can be a very fine line between a minimally expressed
dwarf and a "normal" Miniature Horse that just has bad or
incorrect conformation, but in any case, neither
one of these horses should ever be used for breeding. Many of the
conformation faults that you see in a horse, such as an off bite,
crooked legs, cow-hocked back legs, longer body, etc are all hereditary
and we DO NOT want to pass these faults on to the next generation!

Here is a picture of my Dusty at a baby

This is Dusty at age 8 and 28 inches tall with his winter coat on

Dusty at age 9

I have had folks ask why do you call him a minimally expressed
dwarf instead of a Miniature Horse with a lot of conformation faults?
Well, one reason is that the vets up at TAMU, who did surgery on his front legs as a baby,
told his owner they thought that he was a dwarf, and secondly,
this little guy just has TOO MANY faults added up,
to be just a little horse with bad conformation, IMO.

Many dwarves are born with very weak legs. Some dwarves have such
weak fetlocks or are down so low in the pasterns that they need the help
of a special little shoe to keep them from rolling over to the sides of their
hooves or walking on their fetlocks. That is the way my Little Bit was and
I designed him a special little horse shoe that has since been named the
”Little *Magic Shoes* ” by a gentleman who has a dwarf filly named Angel.
She could not stand on her own when she was born and so the vet wrapped &
braced her little legs, but after a short while she started developing pressure
sores just like my Little Bit did. This man knew he had to do something different
and then he read about the shoes I had made for Little Bit. This gentleman
was so amazed at the result of the shoes when he glued them onto Angel’s hooves,
that he wrote to me and told me that they were Angel’s little * Magic Shoes*, and so the name has stuck.

Angel is now 6 years old and wearing her 6th. pair of *Magic Shoes*!

The photo below left, shows Fairy at about 3 weeks old.
She was walking on all 4 fetlocks when she was born,
so the vet taped tongue depressors to her hooves, which helped her some.

Fairy at three weeks old.

Fairy’s legs at 4 months old after wearing the
little *Magic Shoes*; with just one shoe on her left back hoof.

Here’s Fairy at about 4 months old; barefoot and fancy free!

Precious at 5 years old.

Precious’(above) owners had some little leather braces made
for her, but she learned how to pull on the Velcro straps and take them off.
After several months of trying to keep the leather braces on her,
and not seeing any improvement, her owners stopped putting the braces on her.
Precious is 5 years old now and her joints have fused into this position,
so it is too late for her legs to be corrected. Note the subluxation of her
shoulders as well. Precious is watched very closely
by her vet and he does not think that she is in any pain as of yet.

This is little Chubby, he was adopted by Angel's Momma & Poppa,
but unfortunately not until his little hooves
and legs looked like this from neglect. The farrier did his best with Chubby's hooves,
but he never got to the point where he could wear the *Magic Shoes*,
but at least he was comfortable. A couple years later,
his owners had to make the difficult decision to have little Chubby euthanized,
as his arthritis was making him so very uncomfortable.
There are many of these special little horses that need good loving homes,
but it takes a special kind of person to care for them, especially
the ones with severe dwarf characteristics. These little horses take lots of patience and love,
and you have to be able to afford their many vet, and dentist bills as well.
I have spent thousands of dollars on the seven little dwarves that I’ve had in the last 13 years,
but they give back so much love and enjoyment; I would not trade them for the world!
If I can be of any help to someone who has a little dwarf or
if you have a horse you think might benefit from some little *Magic Shoes*,
please feel free to call me at 979-877-0117 or e-mail me at janell_jensen@yahoo.com
.
Little *Magic Shoes* for "special" little horses
http://www.littlemagicshoes.com/
I also have quite a large network of dwarf Mommas & Poppas
nation wide that are willing to adopt or find homes for little dwarves or
“special” little horses in need of a good loving home.

Genetics
John Eberth

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.

Now the statistical calculations are not complicated
but in order for simplicity I will tell you that if two horses, that are carriers of
the recessive diseased gene are mated, you have a 25% chance of the foal being a dwarf.
Now those calculations are based on the total number of potential
offspring that both of the horses could produce in a lifetime from the billions of sperm
and millions of eggs that could be used to reproduce within the approx.
25 years of reproductive viability of the mare and stallion.
So you need to put things in statistical context if you can.

I know of stallions that have never produced a dwarf, I know mares that have
never produced a dwarf, I know stallions that didn't produce a
dwarf for 10 years then bam, I know mares that didn't produce a dwarf for 10 or
more years then bam, so it needs to be put into statistical context.
I hope you can understand what I am trying to say.
I know stallions that have a dwarf every year, I know mares that have had
2 or 3 dwarfs, so try to see the mathematical picture if you can. You are playing Russian Roulette.

I do believe a large portion of miniatures are carriers of a type of dwarf gene,
remember there are many types. But I know for statistical fact that
there are mares and stallions that do not carry any type of dwarf gene,
now I know more stallions than mares and that is because of numbers and
those numbers used to calculate statistical significance for gene carriers.
Now if we are talking about achondroplasia then I can give you better numbers.
It would be ludicrous for me to speculate total breed percentages because of the
bad label any horse gets from producing a dwarf, so many people lie about if a horse
has produced one or not, so it could be a very large number or it could be smaller
than any of us think. But what I know that exists in all the bloodlines somewhere,
I would think the percentage will be greater than 25%- 50% for achondroplasia,
that does not count the other types of dwarfism I KNOW exist and are more rare,
so the total percentage of horses that are carriers of some type of dwarfism is going to be high.

There has been some research done, pretty much all done by UC Davis Genetics
Lab and University of Kentucky Equine Genetics Lab. Both have preliminary information
but there is nothing that I know of as of now that is anything other than speculative
and no formal articles or definitive results. This is because of lack of public
funding from AMHA or any other donator. There are no science articles per say
that are from any peer review journals that have been written on this disease in our
breed so you won't find any scientific info either. The sample "dwarfs" used by
UC Davis were very limited and I do not know how many different types of
dwarfism there were of the samples they have, I do know there were many different
types I saw them. The same is the case for UK, however, in my research
I have collected more samples than both schools combined and of the same phenotype.
I know these things because of my internship on dwarfism at UC Davis
under the late Dr. Ann Bowlingin 1994, and my own graduate studies at UK.
Understand that there are many different types of dwarfism and/or skeletal
bone growth abnormalities. So you cannot put all "dwarfs" in the same category.
The different phenotypes seen means there are different mutations in different genes,
so it is quite complicated. I have done some work in this area at UK for my graduate studies,
and at the time, I took over what UK had done to try and get somewhere.

My research is privately funded by me, so it is taking much more
time than normal. I am not doing this as an ego trip, but on the contrary,
my business and my life has been in this breed, so that said, I am looking
to better the breed not for me, but for it as a whole. This has nothing to do
with bloodlines or farm names, but of breeding a better horse, and making it
easier for everyone to do so. Because believe me, there are lots of horses of all
bloodlines that are carriers, but there are some statistically that are definitely
not carriers, so it is just a matter of time and money to
find the mutated gene and develop a marker for a test for it.
I do strongly feel that a horse that is a recessive carrier still be able
to be registered and used for breeding. My reasons are simple, one is that
I know many extremely good quality specimens of miniatures that for all purposes
is of great genotype and phenotype quality desired in this breed but that are
also recessive carriers, second that there are other horse breeds that have
diseases that are tested for and those horses that test as carriers still
can be registered and bred, one example is HYPP in quarter horses.
I do feel that if and when a test is designed that all miniatures must be
tested and designated on there papers if they are a carrier and obviously
if a horse is tested and comes back as a dwarf and not just a carrier then
there will be absolutely no reason for dwarfs to be able to still get registered
in our breed registry, like what is going on right now. The third reason I have,
is that when two carriers are bred you only have a 25% chance of producing
a dwarf, interestingly you also have a 25% chance of producing a foal that
is homozygous normal or the ability to produce foals 100% of the time
that are normal even if that foal is later bred to carriers, so there is a lot
there to be used for the betterment of the breed if people would just
learn some basic things about genetic inheritance, and they are very basic.

To also answer another question about inheritance. For the
achondroplasia type of dwarfism I commonly see in miniatures, it is right now thought of as a disease that is inherited as an autosomal recessive trait, which means to show the disease the foal
ABSOLUTELY HAS TO HAVE EACH COPY OF THE GENE COME FORM BOTH PARENTS.
Now the only way you can get a dwarf foal and that foal to have only one copy
of the gene and show the characteristics is if the disease is inherited as an
autosomal dominant, which means one of the parents would be a dwarf.
If you have a mutated gene that causes a disease and that mutated gene is DOMINANT
over the normal gene, then you only need one copy of the mutated gene to show the disease.
Now, the ALL the dwarfisms in the miniatures that I have seen are the results
of dwarfs from normal parents, meaning this is a recessive mutated gene,
and it takes two to show the disease, this is NOT a dominant disease where it only takes one copy to show,
if it did all carriers would be dwarfs, do you follow.

Now if someone bred a miniature dwarf to a normal horse the foal would be normal
UNLESS the normal parent was actually a carrier
then the foal has a 50% chance of being a dwarf.

What you are asking about when a horse that looks normal but has
some slight characteristics that look like a dwarf, i.e., extremely dished head,
is that does that horse carry the recessive dwarf gene. Well, I am going
to give you an answer that has not been scientifically proven in the case
of the miniature horse but other similar instances like this that have
been scientifically proven to occur. What I am about to tell you
involves very complicated dominant and recessive gene interactions
and there is really no way I will be able to fully explain this unless
I had diagrams to show you what happens. There are some terms for
what you see in miniatures, they are called penetrance and
expressivity of recessive genes that become co-expressed
or over-expressed with its counterpart dominant gene.
These terms generalize what is actually a very complicated
biochemical interaction between regulator genes of those genes
that now are co-expressed. Just so you know there are actually
anywhere from a handful to dozens of regulator genes that
regulate the expression or productivity of a single gene or
genes that produce either a structural characteristic or a protein
that is involved in the life support of the body. In simple terms,
your eye color is the light bulb that is on, there are a multitude of
genes that make that eye color appear in your eye just like there
are a multitude of switches and fuses that allow that light bulb to turn on.

So what is going on in the miniature is that those horses that have
characteristics that might be slightly like a dwarf means that that
horse most likely is carrying the dwarf gene recessively, however
because there is penetrance or expressivity occurring you are seeing
that recessive gene being co-expressed with the dominant normal gene.
No, this has not been proven scientifically as fact in the miniatures,
but the same type of thing occurs in every organism known to man at
some point and time with any number of dominant and recessive genes.
I will give you a basic example. In certain flowers that have the red color gene
as a dominant color gene, and the white color gene as a recessive gene, there occurs
in some strains that are carrying both genes that the color of the flower to be pink.
Now do not get fictional here, the red and white do not combine and fade the
color out. On the cellular level, the color cells on the flower's petals, actually
are red cells and white cells of approx. equal numbers, causing the pink color.
Now, technically this is called co-dominance of the color genes, however,
the white is a generally is a recessive color gene in flowers, but because
of penetrance and expressivity of the recessive gene being
co-expressed with the dominant gene you get to see both causing a different color.

So what I am saying is that in my professional opinion, the horses that
are showing slight dwarf characteristics but overall are normal looking,
they most likely are carriers of the recessive dwarf gene with penetrance expressivity.
So in my opinion those miniatures showing some penetrance of certain characteristics
of the dwarf gene are just as good as one that is just a carrier,
HOWEVER, AND IT IS A BIG HOWEVER , I would NOT AT ALL
breed a horse with a monkey mouth, or a short neck,
and I SURE would not breed a horse that had a bad mouth, short neck
AND an extremely dished head, all in one horse,
that could very well be an actual dwarf, just a really good
one that is functionally better than most. Just like there are "tall" dwarfs in humans!!!!!
REMEMBER a monkey mouth is an undesirable inferior characteristic,
it actually can be in and of itself a separate genetic defect from the
dwarf characteristics, because it is seen in large horse breeds
that obviously are not carriers of the dwarf gene.
The short neck is an inferior trait as well, the dished head is really one
person's opinion since you see Arabians and their heads and you know we all
are breeding for an Arabian type head, so there will be varying opinions on if
that is an inferior trait due to dwarf gene or is it an actual sound gene
that is producing a dished head.?? We don't know!!! AN extreme head I would question,
and it will probably obvious if I saw it if I thought it was actually from the penetrance
of the dwarf gene. I do not feel that these extreme headed horses are any
worse than a carrier that "shows no dwarf characteristics," AND genetically
there are not. BUT, if you want to get technical here, the
miniature is a dwarf pony, but has conformation that is physiologically and
biomechanically sound, and has conformation that falls within correct
basic horse conformation standards,ie correct bite, straight legs.
Remember there is no test and some things are personal opinions.