I feed equibites supplement it’s in treat form but I put in her feed, 10 little treats a day balances her vitamins and minerals without all the extra stuff she doesn’t need, super cheap too as a 10kg bag is £18 at my local tack shop and lasts forever!!!
If you compete a lot, always look into muscle relaxation medications, they prevent your horse from having muscle injury, also every 6 months I give a specific medicine for my mare that helps her muscles, her legs and makes her jump better, preventing any serious injury. Talk to your vet, there are many medicines you can give, vitamins that will make your horse health throughout the year.
Remember to be feeding it correctly according to its temperament, workload, weight and age. Make sure its a good quality food.
Keep your horse warm during winter by putting rugs on.
Do a proper warm up and cool off.
Exercise it reguraly.
Regular vet, dentist and farrier appointments.