Study Finds NZ Endoscopy Grading System OK

The research took seven years and involved more than 3,800 yearlings and juveniles.

(Edited New Zealand Bloodstock press release)

The preliminary findings of a comprehensive study involving results from endoscopic throat examinations at New Zealand Thoroughbred auctions has provided conclusive evidence to support the current post-sale endoscopy grading system.

The seven-year study, led by Dr. Jonathan Hope, convenor of the New Zealand Equine Veterinary Association (NZEVA) Endoscopy Committee, confirmed there is no difference in the future performance of horses with grades 1 and 2 post-sale scoping results and those with a grade 3.

According to Hope, the study was undertaken out of a necessity to identify whether there is any evidence to support grade 3s being regarded as scoping failures.

"It is now firmly accepted by buyers and vendors that grade 1 and 2 endoscopy results are a pass, and grades 4 and 5 are a fail,” Hope said. “However, there is a perception from some clients that grade 3 horses may not perform as well, and consequently earn less in stakes, than grades 1 and 2.

"It was my intention that this study should reveal one way or the other whether grade 3 horses should be treated as a pass or a fail, judging by their future performance compared with grades 1 and 2.

"We are thrilled to see that our preliminary findings demonstrate no statistical significance between the two groups of horses. This means we now have scientific evidence to support the robustness of the current grading procedures adopted at the New Zealand sales."

Said Petrea Vela, co-managing director of New Zealand Bloodstock: “We are very grateful to the NZEVA endoscopy committee, the team at Massey University, and particularly to Jonathan Hope, for their considerable hard work to undertake this analysis over many years. There was always a risk in a study like this that the results wouldn't fall in our favor, but with mounting pressure from buyers looking for ways to reduce their purchasing risk, it was a study that needed to be performed and we supported it wholeheartedly.

"It is very heartening to see that the evidence supports the procedures already in place at Karaka,” she continued. “We have confidence from these findings that we have a robust system for the protection of our buyers and vendors, and therefore see no need to review our scoping or grading system at the present time."

In 1995, post-sale endoscopic examination of yearlings and racehorses (older than one year) was introduced in New Zealand. A NZEVA endoscopy subcommittee of Drs. Brian Goulden, Brian Anderson, and Hope established the current convention applied at all auctions in New Zealand. With regard to laryngeal hemiplegia (roarers) the English grading system using a 1-5 scale was adopted. Grades 1, 2, and 3 were a pass, and grades 4 and 5 were a fail.

Since 2003, data on the laryngeal function of yearlings and 2-year-olds at the point of sale has been collected by a team headed by Hope. In August 2010 Massey University assisted Hope with the analysis of the data, comparing it with the race performance of each crop of sale horses (using the number of starts, the number of wins, and the amount of earnings to date).

The aim was to determine what difference in performance, if any, there was between yearlings and Ready to Run Sale 2-year-olds with grade 1 and 2 function and those with grade 3 function.

A total of 3,867 yearlings and 908 2-year-olds were examined. For the analysis, a Grade 1 or 2 horse was randomly selected as a corresponding control for every Grade 3, providing both horses had been examined in the same year and both had raced.

The results of the study showed no statistical significance between the two groups in either case. There was no statistical difference in the number of starts, wins, or stakes earned between the grade 3 and control horses, demonstrating unequivocally that a grade 3 should be regarded as a “pass”.

In the study, the results were the same for both yearlings and 2-year-olds, as well as for both age groups combined.

The findings confirmed that there is no scientific support for buyers to reject grade 3 horses as there is no difference in their performance when compared to grade 1 or 2 horses.

A separate analysis was conducted on horses that did not race, comparing them to both the grade 3 group and the control group (grades 1 and 2). Similarly there was no statistical significance for the proportion of horses that didn't race.

"The post-sale endoscopy system in place in New Zealand has its limitations here as it does all over the world,” Hope said. “The endoscopic examination of horses is not an exact science although the panel of vets at the Karaka Sales has developed a uniformity that provides the highest level of consistency that it's possible to attain under the circumstances.

"These results go a step further to endorse the grading system we already have in place as being scientifically sound. This can give both vets and buyers confidence that every horse passed by the panel, whatever its grade, has the same statistical probability of remaining sound in the wind as any other horse that passes inspection."

The 2011 Endoscopy Report will be finalized in the coming weeks and the full report published later in the year.