It appears the newest fad to give to racehorses to supposedly increase their performance is cobalt. Dr. Teresa Burns from Colorado State indicates in the Horse magazine that cobalt is a trace mineral found in B vitamins that horses require in their body but only in tiny amounts. Although trainers are supplementing horses with cobalt, no one really knows how much cobalt is needed to affect the horse’s body. One study examined five mares supplemented with various doses of cobalt. After being given the compound by IV, some of the horses became anxious, had a rapid heartbeat, had increased blood pressure, and had heart arrythmias. The authors concluded that administering cobalt intravenously to horses has a significant effect on the cardiovascular system that could result in large vessel ruptures, bleeding, severe injury, or death.
There is no known benefit to giving intravenous cobalt to horses in this manner and the increased blood pressure could lead to organ damage in the horse and even human injury.
The heart arrhythmia that was noted has been associated with a high risk of acute death. Dr. Burns indicates we really have no idea what ongoing cobalt administration does in horses as no studies have been performed. We don’t know if there really is a performance benefit, although we haven’t seen one yet, and what long term problems it could cause. However, cobalt has been shown to be fairly toxic in humans and rodents, causing various nerve and hormonal disorders. She indicates that research is being performed on cobalt in horses but she feels it has the potential to be quite harmful and should not be used in horses until research is completed.