There are nothing other than parasites that I am familiar with that car transfer between cats and dogs.  (usual tranmission lines- humans,birds,pigs).  A cat is fine as long as it doesn't care about a small dog- kittens are not bomb proof either, and both can harm a small dog.  Proceed with caution, and only get a cat or a kitten that doesn't mind the yorkie.  Make sure your felines have their immunizations, and you should have no problems, at least this is how we do it.  =-)   
deborah     |