Study brief: Vieira de Castro et al. (2020)

Vieira de Castro, A. C., Fuchs, D., Morello, G. M., Pastur, S., de Sousa, L., and Olsson, I. A. S. (2020). Does training method matter? Evidence for the negative impact of aversive-based methods on companion dog welfare. PLOS ONE, 15(12), e0225023.

In one sentence: Companion dogs trained with higher use of aversive methods showed more stress-related behaviour during training, larger post-training rises in cortisol, and a more negative cognitive bias outside training than dogs trained with reward-based methods.

What was done

Ninety-two companion dogs were recruited from real training schools:

Group Reward (n = 42): three reward-based schools
Group Mixed (n = 22): schools using a lower proportion of aversive methods
Group Aversive (n = 28): schools using a high proportion of aversive methods

Researchers recorded behaviour during training sessions, measured salivary cortisol, and, outside the training context, used a cognitive bias task to assess underlying affective state.

What was found

Dogs in the high-aversive group showed more stress-related behaviours, were more often in tense or low behavioural states, panted more during training, and had higher post-training increases in cortisol than dogs in the reward group.
Dogs in the high-aversive group were more “pessimistic” in the cognitive bias task than dogs in the reward group (a marker of more negative affective state outside the session).
Dogs in the mixed group also showed more stress-related behaviours and more tense states during training than dogs in the reward group.
The authors concluded that aversive-based methods, especially when used in high proportions, compromise companion dog welfare both within and outside the training context.

What this study does not claim

It does not claim that every mixed or aversive session produces identical harm in every dog.
It does not claim that reward-based training solves every clinical behaviour case without specialist support.
It does show a clear pattern of higher welfare cost associated with greater use of aversive methods in ordinary training-school settings.

Note on “mixed” groups

Some commentators point to “mixed” groups as evidence that balanced training is best. In this paper, the mixed group still showed more stress-related behaviour during training than the reward group. The strongest negative welfare pattern was in the high-aversive group. The paper is about welfare costs of method type and proportion, not a contest to crown one commercial brand of training.

Why it matters for policy

Policy arguments often focus only on whether a behaviour can be suppressed. This study measures welfare costs during and outside training. That is the point of the welfare route: if effective alternatives exist, methods that impose higher stress and more negative affective bias are harder to justify for routine companion-dog training.

Primary source

Full open-access paper (PLOS ONE)

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