I am eagerly anticipating watching the Gold Cup today on television. I would love the opportunity to measure the heart size or maximal oxygen uptake of either Denman or Kauto Star. Dr Lesley Young and I have reported the highest verified maximal oxygen uptake in a racehorse in the scientific literature – 219 ml oxygen per kg of bodyweight per minute in a champion hurdler (in a paper in the Equine Veterinary Journal Equine Vet J Suppl. 2002 Sep;(34):467-71). We are not allowed to say which horse though. When it comes to big hearts, Professor David Poole from Kansas estimated that the heart of Secretariat, one of the largest hearts seen in a racehorse, would have allowed him to use oxygen at a rate of around 280 ml/kg/min. I wonder where Sea the Stars would rate? Certainly somewhere up there. For comparison, the highest maximal oxygen uptake measured in elite human athletes is around 100 ml/kg/min. Most ponies would be higher than 100!

I will be making a trip to Cheltenham in June, but to the Cheltenham Science Festival! Geneticist Paddy Cunningham and I are presenting ‘The Thoroughbred Racehorse’ which will look at what makes a winner. All TB racehorses are descended from just 28 animals and understanding the genetics is key to breeding and training a champion.

And finally, the warm weather of the last few days makes me think of what happens each year. As the weather changes and the grass starts to grow, the energy content, especially from the simple sugar content of the grass, increases dramatically. So if you continue to graze your horses the same amount or even more as the days get longer, and continue to feed the same hay and hard feed in the stable, he will get too much energy and you may start to get behavioural problems or worse, laminitis. So either limit grazing, use a muzzle and/or cut back on hard feed.