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Use Of Zilpaterol Earns Most Severe Penalties

Published: December 7, 2010 11:27 am ET

Last Comment: December 7, 2010 9:14 pm ET | 1 Comment(s) | Jump to Comments

The Association of Racing Commissioners International (RCI) today classified Zilpaterol hydrochloride as a 'Class 3' substance and called for the most severe penalty should it be found in a racehorse.

The RCI Board called for a minimum penalty of a one-year suspension and fines in excess of $10,000 for a first Zilpaterol hydrochloride (Zillmax) violation. A second violation would result in a three year suspension and a minimum fine of $25,000. A third positive would result in a five year suspension and a $50,000 fine.

“This drug has no business being in a horse, let alone a racehorse,” RCI President Ed Martin said. “There are some who believe they can circumvent the restrictions on steroids by using Zilpaterol. This cannot be tolerated.”

Zilpaterol hydrochloride is an adrenergic agonist drug licensed in Mexico and South Africa as a feed additive for cattle at slaughter age. Zilpaterol is a relatively new product and is manufactured by the same company that manufactures ractopamine.

“Neither of these drugs has any business being administered to a horse and certainly the presence of either substance in a horse can only be interpreted as a deliberate attempt to cheat by circumventing the current restrictions on anabolic steroids, as the effect is perceived to be similar,” Martin said.

“Based on our review there is no documented medical reason for Zilpaterol hydrochloride to be administered to a horse and therefore if it is found there can be no other motive than a deliberate attempt to violate racingʼs medication rules,” he continued.

The RCI Veterinary Pharmacology Subcommittee, chaired by Dr. Richard Sams, recommended that Zilpaterol be classified as a “Class 3” substances, based upon its pharmacology. The RCI Drug Testing Standards and Practices Committee concurred and the classification was formally adopted today by the RCI Board.

In other action, the RCI Board adopted a recommendation from the Racing Medication and Testing Consortium to reclassify Dimethyl Sulfoxide (DMSO) as a Class 4 substance with a recommended a plasma threshold of 10 micrograms/ml, which would allow for its use as a topical leg paint but would not allow for the oral or intravenous administration of the drug.


December 7, 2010 - 9:14 pmThis product now has a

This product now has a Canadian clearance for use in feeding beef cattle and will soon not be all that hard to find. It will be necessary for officials to keep an eye out for this as it gets into circulation . Currently legal but I do not think it is in widespread use or readily available. Of interest is the same basic warning as for Rumensin which can be fatal to equines.

Also note that it can be very toxic to humans, especially those with heart conditions. perhaps if a crooked trainer uses it, they will suffer the consequences

From the Canadian Compendium of Medicating Ingredient brochures:

Claim 1: For increased carcass leanness, increased dressing percent, improved rate of body weight gain and improved feed efficiency in beef cattle fed in confinement for slaughter during the last 20 - 40 days on feed

Level of Drug:

8.3 mg/kg (0.008%) of the total diet.


Total diet refers to the complete feed plus the roughage and must be corrected to a 100% dry matter basis.

Level of drug in supplements*, premixes and grain rations to be mixed with forages:

At levels so that when used as directed, supplies the average intake as specified below.

Weight of Cattle
(kg) Zilpaterol Hydrochloride Dosage
450 63.50
500 74.70
550 86.74
600 99.60

Feed continuously as sole ration to finishing beef cattle greater that 450 kg body weight for the last 20 to 40 days on feed. Supplements, premixes and grain rations must be thoroughly mixed in the total diet before use. Do not feed undiluted.


Zilmax Premix can be used in liquid supplements under the following conditions:

liquid supplements should be in a pH range of 3.8 - 7.5
liquid supplements should be agitated daily, and prior to use, for 10 - 20 minutes
liquid supplements may contain zilpaterol hydrochloride at a level of 83 - 830 g/tonne.

Treated animals must not be slaughtered for use in food for at least four (4) days after the latest treatment with this medicated feed.
Do not feed to calves to be processed for veal.
Zilpaterol hydrochloride is a beta2-adrenergic agonist. Individuals with cardiovascular disease should exercise special caution to avoid exposure to this medicated feed (Required on Premix and Supplement labels only).
When mixing and handling this medicated feed, use protective clothing, impervious gloves, and a dust mask. Operators should wash thoroughly with soap and water after handling. If accidental eye contact occurs, immediately rinse thoroughly with water. If irritation persists, seek medical attention (Required on Premix and Supplement labels only).
Keep out of reach of children (Required on Premix and Supplement labels only).

Do not feed to animals intended for breeding.
Do not allow horses or other equines access to this medicated feed.
Animals receiving zilpaterol hydrochloride may exhibit an increased respiratory rate as well as elevated levels of creatine phosphokinase (CPK) and creatinine.

Anyone who even considers this for a horse should find themselves charged with animal abuse.

J.Davidson, P.Ag, PAS, Livestock Nutritionist

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