Dear Zooarch Community: Can anyone guide me into some recent papers on
deleterious effects of inbreeding in domestic horses? I have some old
stuff, essentially WWII-era German and Dutch experiments on Friesian
horses that produced "dwarfs", i.e. horses with body (vertebral column)
of normal length but very short legs, i.e. like an equine version of a
Dachshund. Anything more on this I would love to see, but also
hydrocephalus, HYPP, or other "genetic diseases" or evidence of "genetic
load" associated with inbreeding.
Just FYI -- For purposes of an upcoming feature article to be published in
Equus Magazine, I have completed pedigree analysis of every horse who
competed in this year's Triple Crown (i.e., every horse that ran in the
Kentucky Derby, Belmont, or Preakness), and find the same as I found three
years ago when I did the same analysis for the 2015 Triple Crown: every
single competitor descends from the same sire-line (i.e., Bend Or via
Phalaris). All but one horse also has Bend Or/Phalaris for the damsire
line. Further, about one-third of all contestants combined not only
descend from Bend Or/Phalaris but from a horse called Mr. Prospector, who
is himself Bend Or/Phalaris in both sire line and damsire line. What I
said in print in 2015 I will repeat again in this year's feature: "this is
no longer a horse race, it's a clone war."
But I would like to get on Thoroughbred breeders' case even a little more
vigorously by reminding them that breeding speed to speed or winners to
winners saps the vitality of the breed, and if continued, will ultimately
result in loss of viability, soundness, and athleticism. The horse
Secretariat who won the 1973 Triple Crown was also a descendant of Bend
Or/Phalaris in sire line, but his damsire line is quite other, and he has
a beautiful blend of all the founding Thoroughbred bloodlines in his
pedigree. Secretariat broke -- smashed -- all speed records in all three
of the big races, reducing the times not by tenths of a second but by
seconds. Has the subsequent policy (or obsession) of Thoroughbred breeders
of breeding Bend Or/Phalaris to Bend Or/Phalaris resulted in further
reductions in race times? Not at all; they have crept up from 1973 until
the horses are now running at about the same speed they did in 1945.
So help me out, folks, if you can, so that I can give Thoroughbred
breeders the heads-up (or kick in the butt) that they need....in my
function as the horse's advocate, to try to teach them a little biology.
Also, by the way, anyone who wants a .pdf of my report/analysis on
Secretariat ("Secrets of Secretariat's Speed", containing lots of info on
equine gallop biomechanics) or the 2015 Triple Crown report featuring
American Pharoah with gallop biomechanics as well as pedigree analysis,
just contact me off list and I'll send it along. Cheers, and many thanks
-- Dr. Deb
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