Please get him neutered asap. Many males really don't act interested in females or exhibit the undesirable traits like marking until they get to about two years old.
Unless you've had extensive testing done like bile acids test, xrays of knees, eyes certified, thyroid panels done, you can't know that they are healthy from a basic vet check. Maltese and Yorkies are prone to many of the same genetic conditions and you may produce puppies who carry these genetic time bombs. |