Elevated Cobalt Levels Come Under Scrutiny

Cobalt is a trace mineral required by animals for the formation of cobalamin, also known as vitamin B₁₂. This vitamin serves as a cofactor for two enzymes that are necessary for the synthesis of RNA and DNA, and the metabolism of carbohydrates and fats. Production of red blood cells, which transport oxygen throughout the body, is dependent on an adequate supply of dietary cobalt.

Found in small quantities in the soil, cobalt is supplied to horses when they eat grass and hay. As forage is digested, bacteria in the hindgut combine cobalt with other nutrients to form cobalamin, which is then absorbed into the blood from the digestive tract. Horses require a lower level of cobalt than ruminants, easily meeting their needs on pasture that produces signs of deficiency in cattle. In areas of the country where the soil is somewhat deficient in cobalt, such as parts of the Gulf Coast, North Atlantic states, and the upper Mississippi River basin, the level of cobalt is still adequate for grazing horses, even though it is not efficiently absorbed.

Many fortified horse feeds contain a minute amount of cobalt, while other feeds are formulated to contain vitamin B₁₂. Horses usually have a low level of cobalt in their blood, but tests of some horses at the Meadowlands harness racing track in New Jersey have recently shown greatly increased amounts. These levels were far too high to have been reached from ingestion of fortified horse feeds. This finding has led the New York State Gaming Commission to announce its intention of testing for elevated cobalt levels in racehorses.

Cobalt levels had not been routinely quantified in the past, but rumors of possible use by trainers led officials at Meadowlands to request this analysis in equine blood samples. When a large number of tests indicated unnaturally high levels of cobalt, the officials responded by establishing a threshold level for the mineral. Currently, horses whose test results show excessive cobalt levels, set at four times the standard deviation above normal, will not be allowed to race.

Administered by injection, the mineral is thought to have a performance-enhancing effect on horses, possibly by supporting the production of red blood cells. Substances that give an advantage in performance are outlawed for horses that race and train at recognized tracks, and the Association of Racing Commissioners International has begun to review information on cobalt to decide whether this mineral should be classified with other banned substances.

Boosting cobalt levels in horses may enhance performance, but the mineral also has some serious detrimental effects such as interference with proper function of the horse’s heart, circulatory system, nerves, and thyroid gland. Therefore, injecting cobalt is not suggested for horses being trained or used in any discipline.