I should have been clearer- they were saying that the legs were skinnier/smaller in thoroughbreds today than they were 50 years ago. That combined with the fact that the horses' upper bodies are larger and stronger could potentially lead to more accidents. Although, they did say that the number of racing accidents over the past 20 years has been relatively steady.
Regarding inbreeding, I found this abstract from a study done in 2001:
The thoroughbred (TB) horse is one of the oldest breeds of domestic animals, with pedigree records spanning three centuries. Because the population is essentially closed, there is concern about loss of genetic variation. Here we report two parallel analyses. In the first, genetic variation in the current population is measured using data from 13 microsatellite loci in 211 horses with relationships calculated based on allele sharing. In the second analysis, pedigree information is used to calculate genetic relationships between animals based on shared ancestry. These two measures of relationship are compared and shown to be closely related. Together, they provide an estimate of the amount of genetic variation which existed in founder animals. This study confirms the narrow genetic base of the breed and provides comprehensive analysis of contributions of founder animals. Seventy-eight percent of alleles in the current population are derived from 30 founders, 27 of these male. Ten founder females account for 72% of maternal lineages, while one founder stallion is responsible for 95% of paternal lineages.
Not being a scientist I really can't comment on the long-term effects of a lack of genetic variation, but I cannot imagine it's a positive thing.
This is good info. Nice find. Yes, there is a very closed, inbreeding system that has developed the thoroughbred horse. It is generally deemed fact that all modern thoroughbreds can be traced back to only three studs (ca. 1600's)...but danged if I can remember their names.
But the breeding alone doesn't answer the vulnerability issues. The horses that are bred for 'brilliance', that is early speed, are generally lighter, faster, and those prone to the issues you mentioned. Believe me, there are some huge, big-boned race horses out there. And by the way, Eight Belles, a filly, was a larger horse than almost every colt in the Derby.
But there is still this nagging problem of racing horses at such an early age. I think that is a key issue that needs to be addressed. If I were king
)), I'd do the following:
* Ban the use of all whips. While horses are dumber than a box of rocks, and tough enough to require "corrections", I believe we should let them run without the "encouragement" of the whip.
* Immediately study the injury impact of racing on all surfaces and limiting all thoroughbred racing to the best surface, be it synthetic, grass, or dirt (doubtful).
* Prohibit race training and racing of thoroughbreds until the age of 3. (Quarter horse racing may be an entirely different matter.)
