Interesting thoughts.  I wonder just how much inbreeding is too much?  When one looks at the Kentucky Derby results over the last ten years for horses that finished 1, 2, 3 the performances of the Native Dancer line through Mr. Prospector and Northern Dancer are amazing.  Big Brown's pedigree last year bears this out, with Northern Dancer being the grand sire of Boundary(BB's sire) and Nureyev(BB's broodmare sire).  In the previous year Street Sense, Hard Spun and Curlin were all in the family.

 However it appears that Northern Dancer and/or Mr Prospector need to appear within the first three generations, top/bottom or in multiple doses further down the line to enhance success in the Derby.  it would appear also that the Native Dancer line is not just about passing on talent but also precosity and the tendency to be ripe for the Derby test around the first Saturday in May.    

Um, isn't the word eclipse related to things like one thing getting in the way of another -- like the moon between Earth and the Sun? I don't think it's a horse word. Second, really good strains of the thoroughbred are being ignored by breeders -- through Damascus, Relaunch, even Bold Ruler, Domino line, and on and on ... It's not good in the long run, something breeders and the Jockey Club ought to confront. Greed in the absence of creativity is a long-term losing propostion.

• Scot's reply:  The horse Eclipse was so named because he was born at the time of a solar eclipse on April 1, 1764.  The verb "to eclipse" meaning to exceed or overshadow, however, came into use because of the horse, not the astronomical phenomenon.

Eclipse first the rest nowhere was another phrase coined about the great horse!  A very interesting article again.  For me the jury is still out about inbreeding!  Not sure whether it is good or bad. Depends on the horses involved i guess!  

Darley is a very good breeding operation these days and Godolphin a great racing outfit!  Still awaiting Byerley!  Anyone read Jeremy James book about the Byerley Turk?  It is a great read. This horse was not pampered at all and fought in many wars without so much as a scratch!  

Not read any books about The Darley or Godolphin Arabians as yet.  Not sure if they exist though believe there is information about the horses on the Godolphin website, if my memory is behaving itself!!!!!

Many thanks for another great article

God bless

Best wishes

Abbie

Wow, this is such a heavy subject to me as I have bred both horses and Rottweiler dogs and in both cases I have gone for linebreeding not inbreeding. For those that perhaps don't understand linebreeding it is having the same sire on top and bottom but is in the 4th generations or in the 4th and 3rd generations of a pedigree. This way you are using the desirable traits of that sire or it could be the dam and hopefully strengthen the breed. I believe that inbreeding can after time start bringing out undesirable traits and faults. This is such an interesting subject and one that I am constantly learning about.

Um, "readin not breedin", why the confrontational email? HAVE YOU EVER READ this blog before? Scott talks about lost bloodlines alot. I remember a few articles about Domino and about Damascus that were on here recently. Look at this category for what I'm talking about cs.bloodhorse.com/.../default.aspx.

As someone who may be a part owner in a 2 year old TB in the next few months - I tend to fall back on my dog breeding experience. My best Saluki is a very inbred girl who is 3 generations 1/2 brother, sister breeding. She is 14 and very very healthy - my 2 Salukis that were total outcrosses ended up dead before the age of 5 due to cancer. I know genetic diversity is supposed to be a good thing, but...

I think we put too much emphasis on breeding horses that will win the Kentucky Derby. Not that it's bad to aim for a specific race, but it *sounds* like that's the only goal here. I support selective linebreeding and the occasional outcrossing that could produce a horse able to compete in not just the Kentucky Derby but also other (handicap) races.

Inbreeding in general's really not a big deal. When you think about it, all humans trace back to a single female in the far, far past.

I find pedigrees fascinating. There does seem to be a point in which inbreeding becomes counter-productive, but I haven't seen that in line breeding.

There was mention made in another blog about Tiznow being Man O'War's last sire line hope, but I would love to see him bred to an Honour & Glory mare. Or vice versa.

There still seems to be enough bloodstock out there that has no or little inbreeding. Owners making breeding decisions need to consider that if they have a horse that is reaching the 'how much is too much' point in their bloodline.

Inbreeding is needed to a certain point but there is definitely a thing is as too much and it has devastating consequences and one doesn't have to look too much further than purebred dogs to see the disaster.

I would seriously recommend the documentary "Pedigree Dogs Exposed" to anyone even though it is quite horrific.  There's is nothing quite like seeing a dog rolling around on the ground and literally screaming in pain because inbreeding for certain traits have created heads that are too small to fit their brain without severe pressure.

That said the thoroughbred does have a couple benefits.  A) They are bred for performance rather than "looks" unlike many dogs breeds are and B) and matings between mother/son, father/daughter, brother/sister basically never happen (again unlike dogs) even though the jockey club doesn't seem to prohibit it.  Any further info on this?

Although the Darley Arabian may appear at the top of Eclipse's pedigree, he is inbred to the Byerly Turk and such. Eclipse please rise from the dead and lets do a DNA test to see what you really are. Please keep in mind I am looking specifically at Eclipse not who he covered or produced.

hypatia, I've seen some of those dogs. The worst was a Pomeranian whose brain, lungs & heart were normal size & the skeleton was too small. The poor thing had to take medicine to control seizures & let it breathe, it looked horrible. The owners carried him everywhere because his body couldn't handle walking. I used to breed Lhasa Apsos & Shih Tzus. I always had large females that were outbred to small males & never had problems with any puppies. No C-sections either.

Horses aren't even close to being that inbred.

Karen in Indiana, you said that father/daughter, brother/sister, etc crosses never happen. In modern times, NO..However, they have happened in the past and many TBs have these genes in their background.

In regards to Eclipse, I spent hours looking at this horse's pedigree and the only thing one can speculate is the different types of horses that appear in his pedigree.

He is inbred to a mare! She being by the horse Snake, who is from the Lister Turk. Snake is again duplicated from another individual and there is 2 strains duplicated of the stallion Hautboy, another stallion from a Turk.

The Darley Arabian only appears once in his pedigree.

Not to disrespect here, but in all my years of looking at the deep beginnings of the TB, I see more Godolphin and Byerley in their blood than the Darley Arabian.

If one can prove that the Y chromosome is so dominant that it surpasses everything else in the blood, then the Darley line is significant indeed.

Until then, I will wait.

Personally, there is way too much emphasis on the male line and not enough in the "combined" genetic strains.

JMO.

BTW, great article nonetheless.

I've bred several species of performance animals over the past 30 years and I know with out a shadow of a dout that in order to find the hidden faults you must in breed. In oreder to consistantly repeat desired traits you have to in breed. KEEP THE GOOD, CULL THE BAD!