more an more field bred labs are showing up with CNM (centronuclear myopathy) the only way to get this under control is CNM certification.Labs are in high demand an their are breeders out their with a dog that have the abnormal gene. however it takes one from each parent to show the signs of CNM. the test may be around 50 to 100 dollers but its one more + point in your arsonal. an a small price to pay compared to the cost of time an training. before buying a dog ask if the has been tested an let them know you will have it done if they don't like find another breeder (you are the buyer)