Bryan Johnson tackled human longevity. Now he wants dogs to live forever.

Bryan Johnson with his new dog, Katara, at a longevity event in San Francisco this week. Ben Bergman/Business Insider Johnson recently adopted a professionally trained Belgian Malinois to protect him from attackers. The new dog piqued his interest in extending dogs' lives. He plans to put his dog through the rigorous data collection and interventions he does for himself. Tech entrepreneur Bryan Johnson has become famous for his mission to help humans live forever, with his catchphrase "Don't…