By Dr David Marlin

Choosing what supplements to feed your horse or pony can be a minefield. There are many products on the market with many different ingredients. Some of which you may be surprised to know that contain ingredients that have no clinical or scientific proof that they even work! Many supplements are only needed if your horse or pony is deficient in that particular area but for competition horses, there are certain supplements that should nearly always be fed.

The three supplements that I always recommend to all of my competition clients are a good joint supplement, a hoof supplement and an electrolyte supplement.

A good joint supplement can help reduce the wear and tear on a competition horses’ joints. Remember that in the wild horses spend almost all their time walking whilst grazing. During training and competition there is considerable wear and tear. Feeding a joint supplement as a preventative is also preferable to only feeding once you have a problem.  Look for a joint supplement that has a short loading dose (weeks as opposed to months), high levels of key active ingredients and above all, has evidence that it actually works from scientific trials.

Next on my list is a hoof supplement. So many horses have weak or brittle feet and regular shoeing and an erratic climate (e.g. wet summers) do nothing to help this. I always recommend feeding a hoof supplement with a highly bioavailable form of Biotin as once hoof problems start it normally takes 3-6 months to start to reverse the problem and by then your season is over. A good quality Biotin supplement should be one of the least expensive supplements that you feed.  

Whilst many supplements are overused, one of the commonest supplements to be underfed in my experience is electrolytes. Electrolytes are vital for nearly all bodily functions, including nerve, muscle, heart and digestion. Electrolytes are lost on a daily basis in urine and faeces, even if the horse does not appear to be sweating and when horses do sweat, this increases the need for electrolytes further. Horse diets, even for horses at pasture or in light work, are usually deficient in the electrolyte sodium (as in salt – sodium chloride). Whilst many people provide salt blocks, at least three scientific studies have shown that horses DO NOT adequately regulate their salt intake from salt blocks. For horses in more than light work, a supplement which supplies all the major electrolytes is required and should be fed on a daily basis. Many riders make the mistake of only adding electrolytes to the feed in hot weather or in the few days leading up to a competition. However, this presents two potential problems. If the horse has been losing electrolytes on a daily basis for several months in training that have not been replaced by addition to the feed, the electrolytes added before the competition will have virtually no benefit. In this situation horses may be at increased risk of tying-up, colic and or poor performance.  This may also be compounded by the fact that suddenly adding electrolytes to the diet may cause problems with feed refusal and GI disturbance, further compounding the problem of long-term depletion. A balanced electrolyte supplement should therefore be fed at the manufacturers recommendations to all horses in more than light work. Try to avoid products that have sugars (glucose, dextrose) high up on the list of ingredients. You may end up feeding a larger amount of product but very little actual electrolyte. It’s also not true that sugars are needed for horses to absorb electrolytes. Whilst I find most riders underfeed electrolytes, how can you tell if you are overfeeding? The two key pointers here are a noticeable increase in water intake and a wet bed.   

Finally, if you are competing, it’s important that you take care to ensure that you are not feeding supplements that contain substances prohibited from being used under National Federation or FEI rules. For example, valerian is used in a number of calmers but is banned under FEI competition. Look for a statement from the manufacturer which says something like “Suitable for use on horses competing under FEI rules”. In addition to substances which are included on purpose but which may be illegal, there are a number of natural substances that can be present “accidentally” but which can still leave you failing a doping test. Common “contaminants” include caffeine, theophylline, theobromine, hyoscine, hordenine, morphine and atropine which are all banned substances. They are collectively referred to as NOPS – naturally occurring prohibited substances. Again, look for a suitable statement by the manufacturer on the labels such as “This product has been tested to be free of the prohibited substances caffeine, theophylline, theobromine, hyoscine, hordenine, morphine and atropine before being released for sale” and or membership of the BETA NOPS scheme.