Training Troubles: Aversive Methods Compromise Canine Welfare

    Anyone that has ever owned an unruly dog knows the importance of training to behavioral management. In fact, behavior concerns are one of the number one reasons that both dogs and cats are surrendered to shelters or rehomed. There are many ways to train a dog, and much as in the realms of religion, politics, and parenting, every pet owner and professional will have methods that they insist are the right way. This has more recently become a topic of contention in animal welfare circles. Positive reinforcement training (explained further below) has become increasingly popular among veterinary professionals and in zoo settings. The 'Fear Free' movement, founded in 2016 by veterinarian Dr. Marty Becker, has blossomed into a community of pet professionals dedicated to reducing fear, stress, and anxiety in all walks of companion animal interactions. Despite the popularity of 'R+' strategies in animal professional circles, trainers using aversive methods have persisted, and these methods are often hotly defended by users. Evidence-based recommendations have also been hard to come by-- a 2017 literature review found that the current available body of evidence does not strongly support that negative outcomes are associated with aversive methods. However, a new study, published December 2020 in PLOS One, provides "the first empirical study to systematically investigate the effects of different training methods on the welfare of companion dogs within and outside the training context."

Before circling back to the findings of the new study, a brief review of operant conditioning is in order. Training methods can be divided into quadrants based on what is done and why it is done. Positive and negative refer to whether a stimulus is given or taken away. Reinforcement and punishment refer to whether the intent is to increase a behavior or decrease a behavior, respectively. These combinations create the following descriptions:

Positive punishment is the addition of an aversive stimuli to reduce an unwanted behavior. For example, the unpleasant sensation of prongs against a dog's neck when pulling at the leash on a prong collar. 

Negative punishment is the removal of a desired stimuli to reduce an unwanted behavior. For example, no longer walking forward when a dog pulls. 

Positive reinforcement is the addition of a desired stimuli to increase a wanted behavior. For example, giving a dog treats when they walk with slack in the leash. 

Negative reinforcement is the removal of an aversive stimuli to increase a wanted behavior. For example, the unpleasant sensation of prong's against a dog's neck going away when they stop pulling and walk with slack in the leash. 

    The study in question sought to answer the question of whether or not aversive training methods (positive punishment and negative reinforcement) negatively impact the welfare of dogs. The answer they arrived at is yes, that these methods induce stress and impact canine mindset even outside of a training setting. This study is open access and can be read online for free. Here are the highlights:

Methods & Sample:

• Study authors recruited 7 canine training schools
• Schools were classified into 'aversive,' 'mixed,' or 'reward' based on the frequency with which each of the four methods discussed above were employed during six randomly selected video training sessions from each school.  
• Head trainers at each school were asked to indicate dogs that met inclusive criteria: new to the school (less than 2 months in training) and free of underlying conditions/concerns that could increase stress (aggression, separation anxiety, etc). 
• The final sample size consisted of 92 dogs, 28 at Aversive schools, 22 from Mixed schools, and 42 from Reward schools. Only 79 of this sample participated in the cognitive bias task. 
• Animal welfare was evaluated both in a training setting and in a non-training setting
• During training sessions, the first 15 minutes of the session were recorded on three different occasions for each individual dog. These recordings were evaluated for behaviors associated with stress, such as lip licking. Observers were blind to the training classification of the school when evaluating display of stress related behaviors. 
• Saliva samples were collected from the participating dogs to measure cortisol levels, a hormone positively correlated with stress
• To evaluate welfare outside of the training setting, dogs were made to perform a cognitive bias task.
• This test evaluated the time taken by a dog to approach an empty food bowl in a location that had previously been associated with either an empty or a full food bowl. 
• Dogs in a positive affective state are expected to be eager to seek out a potential reward, while dogs in a less positive affective state are expected to take longer in the same scenario to seek out the same reward

Results:

• Behavior during training session
• A strong association between the Aversive group and frequency of stress-related behavior displays, such as yawning and lip-licking was noted
• Tense behavioral states were seen more frequently in the Aversive and Mixed group than Reward group
• Cortisol levels
• Cortisol levels were significantly higher in the Aversive group when compared to the Reward group
• Cognitive Bias test
• Dogs from the Aversive group were slower to seek out an anticipated reward than dogs from the Reward group. 
• This suggests a lower affective state, associated with negative welfare

The authors conclude:

Overall, our results show that companion dogs trained with aversive-based methods experienced poorer welfare during training sessions than dogs trained with reward-based methods. Additionally, dogs trained with higher proportions of aversive-based methods experienced poorer welfare outside the training context than dogs trained with reward-based methods. Moreover, whereas different proportions of aversive-based methods did not result in differences in dog welfare outside the training context among aversive-based schools, a higher proportion of aversive-based methods resulted in poorer welfare during training. To our knowledge, this is the first comprehensive and systematic study to evaluate and report the effects of dog training methods on companion dog welfare. Critically, 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. 

In other words, aversive methods negatively impact the psychological state of dogs, and therefore their welfare. This further supports previous studies that have suggested as much. 

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