I am just wondering if ACL tears can be genetic? Such as, a dog has weaker ACL's that are more apt to tears do to bad breeding. Helena tore both of her knees before age 2. I have always wondered if it was my fault for letting her run and jump too much before age one.... or if she could have been genetically predisposed. When Helena tore her first acl, I don't know how she did it, she just came up lame one day. And I don't know what happened. The second happened when she was running with another dog. Is there a way to prevent it?