The rules for TCO2 testing in Australia:
VETERINARY
TESTING FOR THE ADMINISTRATION OF BICARBONATE & ALKALINISING AGENTS IN RACEHORSES
Dr Craig Suann
For many years, it has been a practice for racehorses to be administered small quantities of sodium bicarbonate or other alkalinising agents in the feed prior to racing. It has been thought that sodium bicarbonate used in this fashion helps horses recover after a race by dissipating muscle lactate, helps horses that \"tie-up\", and prevents \"acidosis\" due to high grain feeding. However, there is no scientific evidence that bicarbonate supplementation is useful in managing horses that are known to \"tie-up\", and its effects on recovery and digestion have also not been demonstrated.
A major concern in both horse racing codes is the alleged practice of large amounts of sodium bicarbonate administered by stomach tube to horses prior to racing. Apart from causing diarrhoea and colic, the image and integrity of racing and the welfare of racing horses are at risk due to this practice. It has been proposed that bicarbonate loading might improve the performance of horses by delaying the onset of fatigue through the buffering effect on lactate accumulation, particularly for horses competing in staying races. While there have been no scientific studies that have statistically demonstrated improved performance in horses due to bicarbonate administration, there is no doubt that there is a strong view amongst many trainers worldwide that there are beneficial effects due to bicarbonate administration in certain horses competing in races over certain distances.
Rules were introduced by both horse racing codes in 1992 to limit the amount of bicarbonate and related substances that could be administered to racehorses prior to racing. These substances are collectively called alkalinising agents. It is important to understand that the Australian Rules of Racing do not refer to bicarbonate specifically, although alkalinising agents are noted in the list of pharmacological categories in AR178B(2). The bicarbonate concentration and the plasma total carbon dioxide concentration are closely correlated, and it is more convenient to measure the plasma total carbon dioxide concentration rather than the bicarbonate concentration.
Sampling for compliance with the total plasma carbon dioxide rule {AR.178C(1)(a)}
In thoroughbred racing, the Australian Rules of Racing make it an offence for a trainer to present a horse to race with a plasma total carbon dioxide (TCO2) concentration in excess of 36 millimoles per litre (mmol/L). This concentration is the same as the international threshold for TCO2 contained in Article 6 of the International Agreement on Breeding and Racing. Because other alkalinising agents are also converted to carbon dioxide by the horse, the use of all alkalinising agents is controlled by the same rules.
The Stewards can monitor and detect a prohibited administration of an alkalinising agent prior to racing using simple but effective sampling strategies. A blood sample is all that is needed and the Stewards can direct the sampling of as many runners as they please, and the sampling of any runner on more than one occasion. If necessary, horses may also be sampled after racing, or tested unannounced in their stables if there is a concern about a race day value.
Naturally occurring, feeding and husbandry factors that affect the TCO2 concentration
In thoroughbred racing, the Australian Rules of Racing make it an offence for a trainer to present a horse to race with a plasma total carbon dioxide (TCO2) concentration in excess of 36 millimoles per litre (mmol/L). This concentration is the same as the international threshold for TCO2 contained in Article 6 of the International Agreement on Breeding and Racing. Because other alkalinising agents are also converted to carbon dioxide by the horse, the use of all alkalinising agents is controlled by the same rules.
The Stewards can monitor and detect a prohibited administration of an alkalinising agent prior to racing using simple but effective sampling strategies. A blood sample is all that is needed and the Stewards can direct the sampling of as many runners as they please, and the sampling of any runner on more than one occasion. If necessary, horses may also be sampled after racing, or tested unannounced in their stables if there is a concern about a race day value.
Naturally occurring, feeding and husbandry factors that affect the TCO2 concentration
Naturally occurring levels of total plasma carbon dioxide
The plasma total carbon dioxide concentration (TCO2) is a measure of the amount of available carbon dioxide in the blood of the horse. The TCO2 concentration varies between horses. A number of factors can reduce the natural level, but there are no naturally occurring factors that have been proven to increase the TCO2 concentration to the prohibited range in a normal horse.
In a survey of 515 stabled thoroughbred racehorses in metropolitan regions around Australia and published in the Proceedings of the 13th International Conference of Racing Analysts and Veterinarians in 2000, the average plasma TCO2 concentration was 30.77 mmol/L. Taking into account the variation of the sampled horse population (known as the standard deviation which in this survey was 1.38) the odds of a \"normal\" horse having a TCO2 level exceeding the action limit set out in the Rules of thoroughbred racing were greater than 600,000 to 1.
Types of alkalinising agents and frequency of administration
Apart from sodium bicarbonate, numerous other alkalinising agents can also increase the TCO2 concentration if fed or administered to a horse. Alkalinising substances that are sometimes found in proprietary preparations and feed additives, or are sold separately for administration include citrates and citric acid, and lactate, succinate and acetate salts. There is a limit to the amount of alkalinising salts that a horse will ingest, although some can be conditioned to eat a high salt diet, and some citrate preparations are made to be very palatable.
It must be remembered that the Rules do not make reference to the source of the alkalinising salts. Bicarbonate and other salts fed in the ration are treated no differently to those administered as a drench. The effect of feeding or administering multiple sources of alkalinising salts will be additive, which means that all of the doses and sources could give rise to a plasma TCO2 concentration that contravenes the Rules. To avoid this, trainers must know every alkalinising agent that is given to their horse, including those included in prepared feed and in commercially available supplements.
Trainers are also reminded of their obligations under the following Rules of Racing when it comes to the administration of bicarbonate and other alkalinising agents:
\"AR.64G.
1. No horse engaged to be run in a race or trial shall without the permission of the Stewards be stomach-tubed within 24 hours of the appointed starting time for such race or trial. For the purposes of this rule \"stomach-tubed\" means any application to a horse of a naso-gastric tube.
2. Any horse that has been stomach-tubed contrary to the provisions of subrule (1) of this rule may be prohibited from starting in any relevant race or trial, and the trainer of the horse and any other person involved at any relevant time may be punished.\"
\"AR. 178E
1. Notwithstanding the provisions of AR.178C(2), no person without the permission of the Stewards may administer or cause to be administered any medication to a horse on race day prior to such horse running in a race.
2. The Stewards may order the withdrawal from a race engagement any horse that has received medication in contravention of subrule (1) of this rule.\"
(Add to definitions in AR.1:\' medication means treatment with drugs or other substances\')
In effect, AR.178E prohibits all treatment of horses with drugs and other substances (including sodium bicarbonate and other alkalinising agents) by injection, stomach tubing, oral syringe, topical application, inhalation or other means on race day prior to their racing engagement. Essentially, only normal feeding and drinking will be permitted pre-race on the day of the race.
Analysis of blood samples for TCO2
The Rules of Racing refer to the plasma total carbon dioxide concentration. The Australian racing laboratories agreed many years ago to use the same instrument (\"Beckman Synchron El-ise\") and the same methods and controls to minimise variation within and between laboratories. The same instruments and methods were used for the developmental work that led to the Rules. Further, a certified reference material is used to guarantee the precision and accuracy of the measurement of plasma TCO2 as well as the use of more reliable calibrators for the Beckman instrument.
Uncertainty in analytical measurement
The allowance for uncertainty of measurement is always made in the trainers\' favour. Currently, an allowance of 1.0mmol/L applies to the plasma TCO2 measurements made by all the Australian racing laboratories when samples are screened and confirmed.
Conclusion
The threshold for plasma TCO2 is designed to control the inappropriate pre-race administration of bicarbonate and other alkalinising agents. Trainers need to be careful if they are going to supplement their horses with these substances in the period leading up to a race. A good working knowledge of the husbandry factors that influence the plasma TCO2 concentration is required before the risk of an infringement of the Rules can be assessed. Trainers are also reminded of their obligations with respect to AR.64G and AR.178E when considering the administration of sodium bicarbonate and other alkalinising agents to horses close to race time.
The Jockey Club Thoroughbred Safety Committee Recommendations:
www.jockeyclub.com/resources/tco2.pdf
