A panel discussion during the first day of the Welfare and Safety of the Racehorse Summit on the current state of the Thoroughbred and possible reasons for declines in average starts per horse and average field sizes over the past five decades yielded no consensus.

Comprised of three veterinary professionals involved in regulation, a prominent equine surgeon, and racing's all-time leading money-winning trainer, the panel at the July 8 summit at Keeneland Race Course in Lexington, Kentucky, discussed a wide array of scenarios, ranging from whether the 21st century Thoroughbred is too fragile, the possible effects of medications on whether horses start less now, and even possible economic decisions that have resulted in horses not racing as much as in the past.

To begin the discussion on "Today's Thoroughbred—What Animal Are We Dealing With?" moderator Ed Bowen noted that average annual starts per horse have declined from 12 in 1960 to just 6.2 in 2013 and average field size has fallen from nine to just under eight horses per race during the same period.

He also said there are 31 mega-stables that in 2013 each had more than 150 individual horses start, representing 7.5% of all U.S. starts.

But rather than pinpoint the "usual suspect" of greater dependency on drugs as a causative effect, most of the panelists agreed that different training techniques and priorities for horse owners played as much of a role as medication.

Rick Arthur, DVM, California Horse Racing Board equine medical director, said there has been a trend more toward working horses up to a race rather than using a prep race to get a horse fit