A new study suggests that dog training methods based on negative punishments can cause long-term harm to the animal. Much research in the past has studied training methods in general, including for dogs working with police or with search and rescue operations. But the latest study centered on dogs kept as companion animals for humans. Such dogs are often considered part of the family and need training on how to behave around people. Researchers from Portugual’s Unviersity of Porto led the study. The researchers carried out experiments involving two kinds of dog training methods – aversive and reward-based. Aversive methods depend on the use of some kind of negative action in answer to unwanted behaviors.