The Chihuahua is known for open fontanels, a soft spot located on the top of their skull. (dogbreedanswers.com)
Pomeranians suffer a lot from open fontanels, slipping patellas, heart murmurs, etc.. (breedingbusiness.com)
Since open fontanels are either hereditary or genetic, once a good breeder determines which parent dog carries the gene the parent dog should be retired from the breeding program and spayed or neutered. (cruisincavaliers.com)