I believe there is some confusion about the difference between genuine genetic dwarfism, and physical abberations that *might* be caused by environmental factors-and that while it may be possible that environmental factors(of varying kinds)*might* cause physical deformities, it is my considered opinion that seldom, if ever, would such deformities manifest themselves in the same ways as true dwarfism, and it should be quite possible to recognize one from the other!
Tabitha(along with others) is well-spoken in her post--however, I would have to disagree with her evaluation of the 'odds' of the offspring of Bond Tiny Tim having the dwarf gene/being dwarves themselves! Because of the nature of the pairing of recessive genes (Mendelian genetics), ALL offspring of a genetic dwarf WOULD at least be CARRIERS of one copy of the dwarf gene-and if ANY of the horses the dwarf was bred to was itself a CARRIER-that is, had one copy of the gene for dwarfism-then the offspring of those particular two would ALL be either CARRIERS or themselves be dwarves-period. This would be true no matter which 'direction' the breeding went-that is, whether the genetic dwarf were the sire OR the dam - however, it is the STALLION who can have more of an overall effect on progeny, because a stallion may sire numerous offspring in a year, while a mare(at least, until embryo transplant gets established....
)can produce only ONE in a year!!
The further 'away' from the original use of a genetic dwarf for breeding you get-i.e., grandget, great-grandget, and so on down the line-the 'lesser' the likelihood of a high percentage of CARRIERS in the bloodline- theoretically(and realistically, too, I feel sure.) THIS is why there is no need to 'throw out' EVERY individual of any given bloodline because back when, someone used a genetic dwarf ancestor for breeding. Because we do NOT have a way to test for CARRIERS, it IS something of a 'crap shoot' EVERY TIME two miniature horses are bred to each other; currently, the only way to KNOW pretty certainly that a horse is a CARRIER is when a dwarf is the result of a breeding-because this points to both sire AND dam being CARRIERS. THIS, to me, is reason enough, in and of itself, to NOT continue to breed those particular two individuals again, to ANY other horse. Our breed SERIOUSLY needs the research to be able to begin to identify carriers; similar serious genetic problems have (albeit after a lot of shameful foot-dragging...)been 'managed' in at least a couple of other breeds(AQHA, and by extension, their outcross breeds, and Arabians); the same should surely be possible in our breed.
(Those of you who have been here awhile know that I HAVE had a dwarf born here, and that I HAVE 'put my money where my mouth is', losing a sizable investment in the process--MY choice, and MY action-and I would do it again. )
I do NOT believe that removing known dwarf producers from the breeding pool would decimate the breed-nor do I think that it would completely eliminate the occurance of dwarves within the miniature breed-certainly not soon-as there are a number of unknown CARRIERS still 'out there'-AND, there is still the possibility of point mutations. I DO think it is the proper action to take.
(How many breeders do YOU know that volunteer that 'this' sire and/or 'that' dam have produced a dwarf??)