How many studies do we need to figure that out?

A new study out of Portugal adds to the mounting evidence that dogs trained using aversive stimuli—i.e., positive punishment and negative reinforcement—show evidence of higher stress levels compared to dogs trained with reward-based methods—i.e., primarily positive reinforcement.

In the study, researchers at the University of Porto filmed the behavior of 92 companion dogs from seven dog training schools in Portugal. Those schools use either aversive methods, reward-based methods, or mixed methods (which combine the two).

After analyzing the results, the researchers tested saliva samples from the dogs for the stress-related hormone cortisol.

They found that dogs trained using aversive and mixed methods exhibited more stress-related behaviors and a bigger rise in cortisol levels than dogs trained with rewards.

Additionally, the researchers conducted a cognitive bias test on 79 of the dogs. In that test, dogs from schools using aversive methods responded more negatively to ambiguous situations compared with dogs receiving mixed- or reward-based training.

The authors say that while previous survey-based studies and anecdotal evidence have suggested that punishment-based training techniques may reduce animal welfare, this is the first large-scale study of companion dogs in a real training setting, using the types of training methods typically applied in dog training schools.

They conclude, “Our study points to the fact that the welfare of companion dogs trained with aversive-based methods is at risk, especially if these are used in high proportions.”

Karen Overall, MA, VMD, PhD, DACVB, associate professor of Behavioral Medicine in the Department of Health Management, Atlantic Veterinary College, at the University of Prince Edward Island, Canada, told NEWStat that no one should be surprised at the study’s results.

“Given that the data continues to mount that aversive methods are damaging to dogs in terms of their cognitive performance and behavioral and emotional states . . . you would think industry groups and veterinary organizations would be jumping out of their skins to support such overwhelmingly clear data with recommendations for best practices, evidence-based educational campaigns, and a legislative push for sanctions,” Overall said.

She added that it’s unfortunate so few veterinary schools have full-time behavioral medicine programs with faculty also committed to research because veterinary students—and even the faculty—at those schools are deprived of the value of these advances: “Patients suffer as a result,” she said. “It’s past time for us to do better and change our behaviors in accordance with scientific findings.”

For more information on behavior and training, see the 2015 AAHA Canine and Feline Behavior Management Guidelines. Client educational behavior brochures informed by these guidelines can be found here.

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