When you are washing your horse, make sure you do not wash his or her face. Their health will go down.

When you are cleaning your horse's body. Choose the top brush first and go down the line in order each brushing the entire body. The last one is the comb. Use the comb to brush or comb its mane. When you are all done on that side, switch to the other side.

When you are cleaning the hooves, be careful not to touch where there is no muck "dirt". Its health will go down.