YOU don't. You need to see a vet and speak to them about it. Preferably one that is recommended by people for whatever crop and breed you have (yep, they are different). It's a personal preference and may need to be done for show but not so much as pets. Be sure you are aware that it is often a riskier surgery due to their position and also all the after care involved that you will have to do at home for this surgery.