How can I deter my horse from always urinating in the cross ties?
Wow. This is a pain in the rear. Some horses are habitual about where they like to urinate. In the crossties, in the arena, in a certain area in the paddock. They also tend to be habitual about when they urinate, after exercise, for example.
You can teach any horse to urinate "on command". This comes in quite handy, especially if you are working at a show and you don't want the ride to be compromised. It also helps for those horses that habitually urinate in not so great places or times.
You will need to be patient, consistent, and positive. You will need to associate urination with a sound, such as a whistle. First, you have to catch your horse in the act. In the stall, paddock, or where ever. Try and whistle the entire time your horse is urinating.
Then, you need to throw your horse a huge party. Lots of positive praise. Do this a lot. Lots of parties. Lots of patience.
After a while (depending on the horse, a few days to a few weeks), you will be able to whistle and your horse will urinate. So, if you have a class at a show, or your horse needs to urinate before you get into the cross ties, you have a tool.
Even after you have your horse urinating on command, you must keep up the positive reward.