There are many reasons to have your beloved pet spayed or neutered. The main reason is for the health of your Yorkie or Maltese pup. The greatest risk your pet has of developing cancer at a later date is in the reproductive organs. We want your puppy to live a long long healthy life. Reduce that risk by having him/her altered. Schedule the surgery after the Yorkie/Maltese is at least 6 months old and have your vet check the puppy teeth to see if any need to be removed. Ask questions of your vet, make sure they use a heart monitor on the puppy while they are in surgery and use the minimum amount of gas to put the pup to sleep, so they can wake right up without risk afterwards.