Havanese health is a paramount consideration when choosing not only a breeder but a particular puppy.  The breeder should have completed all of the health testing on both the parents of the prospective puppy.  After completion of the health test, the results of those tests should be submitted to OFA (Orthopedic Foundation of Animals) so that those results can be visible to all.  You should be able to search for the result on OFA's website https://www.ofa.org/  by the parent's AKC registration numbers.  The tests include an annual Eye Cerf, BAER testing (hearing), Hip and elbow X-ray evaluations, Patella check and last but not the least, Cardiac certification.  If the parents aren't affected by these diseases, the incident in the resulting puppies goes down significantly.  Always choose the best breeder by the information and education the breeder has not by the cuteness of the puppy because we all know that puppies are irresistible.