Strengthing the tenderloins

Question
Hello Jessica,

                         I'm a screenwriter and I'm currently writing about horse
racing, problem is, I don't know much about horses. In my script, the horse
has weak tenderloins and his trainer is trying to strengthen them in time for a
race.  
     My question is:

                                Is there anything that can be added to a horse's diet
that might strengthen its legs?  

Answer
Hi, I assume you mean the loin which runs along the top part of a horses barrel.  The loin is also referred to as the coupling which connects and hind quarters and back.  It also runs down along the side behind the last rib on the horse.  So in layman terms your question is regarding the horses development of a strong back and hind quarters.  To answer your question, you would want a diet with high protein to for the development of strong muscles.  If you're trying to strengthen tendons which run down the horses legs, you would need to have stem cell therapy to promote stronger tendons as there is no supplement that will strengthen a tendon.  Hope this answers your question.

Regards, Jessica