Why the AGCO Lowered the TCO2 Test Threshold

Ontario’s decision to lower the threshold for total carbon dioxide (TCO2) tests on racehorses is mostly a matter of aligning itself with the rest of the Canada and more of the horse racing world, said Jeremey Locke, director of the regulatory compliance branch, operations division at the Alcohol and Gaming Commission of Ontario (AGCO).

On May 3, the AGCO announced that as of June 1, 2021, the AGCO will lower the thresholds for TCO2 from 37mmol/L to 36mmol/L, and from 39mmol/L to 38mmol/L for horses registered in the Exercise Induced Pulmonary Hemorrhage (EIPH) program.

An AGCO release explained that “Carbon dioxide (CO2) occurs naturally in the blood of horses at varying concentrations. This natural level can be anywhere from 26/27mmol/l to 31/32mmol/l. An elevated TCO2 level is an indicator of the use of alkalizing agents, which may compromise the welfare of the horse when provided in excess, and the integrity of racing by artificially enhancing a horse’s performance.”

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Locke said the TCO2 program started in 1999 “with funding and technical expertise provided by the CPMA (Canadian Pari-Mutuel Agency).”

To retain funding for the program, the AGCO agreed with a CPMA request to lower TCO2 threshold limits primarily, “to harmonize the Canadian TCO2 program with other programs around the world by adopting the international threshold established by the International Federation of Horse Racing Authorities (IFHA) of 36mmol/L. Since there is no international threshold for EIPH horses, a decrease of the same magnitude or of 1mmol/L is proposed for this group of horses.

“All provincial racing regulators were approached by the CPMA and advised that they wanted to change the TCO2 levels. CPMA did the due diligence on this and explained that all of Canada needed to get in line with the internationally accepted thresholds… The IFHA has established 36 mmol/L of CO2 in blood plasma as their recommended threshold. Many jurisdictions around the world, with the notable exception of many in the U.S., which follow the ARCI (Association of Racing Commissioners International) model rules (that set the TCO2 threshold at 37mmol/L).”

Apart from aligning with the international standard, Locke said, “There is considerable empirical evidence to suggest that the use of alkalinizing agents in excess of normal feed supplementation artificially enhances the performance of horses. By implementing the lower threshold, Ontario maintains funding for the program while safeguarding the welfare of the horse and upholding the principles of fairness in the racing product” and increasing “integrity in the sport.”

What has the data told the AGCO?

Locke said the AGCO has access to “approximately eight years of TCO2 data through racing forensics… The data demonstrates a significant variation between trainers, with some trainers having lower levels, and others routinely having higher levels. The average TCO2 level has been relatively consistent.”

In 2019, the AGO shifted its approach for selecting horses to be tested for TCO2 “based on evidence and risk assessment rather than taking a random approach. TCO2 level in horses selected for testing increased for a period of time but they have since normalized to pre-2019 levels.”

Ontario’s Rules of Racing are also being updated on June 1 to implement a ban on race-day medication that prohibits the administration “of medications, drugs and substances to any horse starting 24 hours prior to the post time of the first race of the day they are scheduled to race.”

Locke said the fact horses given alkalizing agents return to pre-administration TCO2 levels within approximately 24 hours will mean there is an “extremely low probability that a horse will exceed the applicable threshold due to natural causes… if trainers are following the 24-hour race day medication ban.”

“As with all rule changes, the AGCO will continue to monitor this change for effectiveness and fairness,” Locke said.

Lindinger questions Tco2 program

About the same time the AGCO announced the lower TCO2 thresholds, Dr. Mike Lindinger, an equine exercise physiologist, sent an open letter saying, in part, that Ontario’s TCO2 testing has “not kept pace with technology and equine physiology.”

The CPMA was asked about Dr. Lindinger’s letter and Samantha Seary, the acting media relations officer, media services, public affairs branch for Agriculture and Agri-Food Canada (AAFC) confirmed that “the testing protocol has not changed since the program was implemented in 1999,” adding that “the testing is carried out using the same analytical approach that was used to establish the TCO2 international threshold.”

Seary said the new TCO2 threshold of 36mmol/L “was adopted by the International Federation of Horseracing Authorities’ (IFHA) Advisory Council on Equine Prohibited Substances and Practices, after consultation with the Association of Official Racing Chemists and the International Group of Specialist Racing Veterinarians, and approved by the Executive Council of IFHA. This threshold has been in place for at least 10 years in several countries, including UK, New Zealand, France and Australia.”

As to Lindinger’s contention that the CPMA is using the wrong range for TCO2 that naturally occurs in horses, Seary said, “The current instrumentation used to determine TCO2 levels in Ontario and its associated reference ranges have been extensively validated and documented for forensic use in Canadian and international studies. This instrumentation operates with the same analytical approach that was used to establish the TCO2 international threshold. Data collected from Canadian racehorses using this instrument support the implementation of the international threshold.”

Seary also said Lindinger’s citations, “offer generalized results without any interpretation. The wide range of TCO2 values need to be evaluated in the light that the type of equipment and, consequently the analytical approach to calculate TCO2 concentration was not consistent in all studies. Some of these instruments measure pH and partial pressure of CO2 and from these values compute the TCO2 concentration. Others, like the one used in Canada, measure TCO2 directly. Thus, TCO2 values will vary from instrument to instrument depending on the analytical approach used.

“For example, in a paper by Waller and Lindinger (Acta Vet. Scandinavica, 2007, 49:38), the Nova Stat Profile was reported to yield bicarbonate and TCO2 values 2-3 mmol/L higher than the instrument used in Canada. Furthermore, the studies report TCO2 values measured from uncontrolled horse populations where no information is available to determine if some of those horses have been administered substances that can elevate the natural TCO2 levels. Other studies measured TCO2 levels in non-racing horses.”