NOTE: Health testing is an important tool to assist breeders in determining whether a Mastiff should be used in a breeding program, but should not be considered the sole criteria in making such decisions. 

Other factors to be considered are conformational correctness (see AKC standard) and soundness of temperament.  In most cases, health testing is not a guarantee that the breeding will not produce affected puppies, but will greatly reduce the likelihood of this occurring.   One exception to this is the PRA DNA test.  If both sire and dam test free for the PRA gene, their breeding cannot carry the gene for or produce offspring with PRA (progressive retinal atrophy).This recent leap forward in research is now providing Mastiff breeders the unique opportunity to virtually eliminate PRA, a leading cause of blindness, from the Mastiff breed. 

• Read more about PRA & this recent genetic breakthrough...