Question

I train in very hot, humid conditions in Australia. One of my Thoroughbreds pulled up with a mild case of the thumps after her last two starts. Though she won her races, this obviously concerns me. I have tried to make sure the mare’s dietary calcium-to-phosphorus ratio was acceptable, and subsequent bloodwork seems OK. She eats 15-17 lb (7-8 kg) of a high-energy micronized sweet feed a day, 4-9 lb (2-4 kg) lucerne (alfalfa)/oaten hay, ad libitum Rhodes grass hay, and almost 1 lb (0.9 kg) of lucerne (alfalfa)/wheat chaff. I’d like to use a custom feed mix that contains corn, oats, barley, sunflower seeds, and tick beans.

Answer

I have formulated a concentrate using the ingredients you’ve mentioned. One note, however: I have removed the tick beans and replaced them with lupins as a preferable legume for palatability and starch content. For those unfamiliar with tick beans, they are also a source of protein. Because tick beans have lower levels of important amino acids, namely methionine and cysteine, I replaced them with lupins for this mare. Lupins are also less likely to be left in the feed bin by a picky racehorse. Further, I would recommend using a high-quality vitamin and mineral supplement with the mix.

For horses prone to thumps, we recommended avoiding the following, if possible:

• Excitability that leads to excessive sweat loss;
• Dehydration by leaving the horse without water;
• Alkalosis by ensuring the use of a scientifically formulated electrolyte that will replace electrolytes lost from sweat; and
• Excessive calcium in the normal diet, which allows the horse to become accustomed to conserving calcium day-to-day and reduces the likelihood of excess calcium loss on race day.

For your mare, we recommend:

• Restore electrolyte (30-60 g per day when she sweats) in addition to salt lick access;
• Use the recommended serving of a vitamin and mineral supplement;
• Up to 4.4 lb (2 kg) of lucerne (alfalfa) hay per day, with additional hay, either Rhodes grass or oaten hay;
• Use an electrolyte paste with added bioavailable calcium after her final gallop and twice on the day before the race;
• Feed electrolyte on race day; and
• Feed lucerne (alfalfa) hay on race morning to provide additional calcium.

For those unfamiliar with Rhodes grass, it is a tropical forage useful for both pasture or hay and is of especially high quality when young.