Combining Animal-assisted Intervention and Placebo-induced Analgesia

A growing body of literature suggests that animal-assisted interventions (AAI) have important clinical effects on humans, e.g. decreased physiological stress, reduction of depression and anxiety symptoms and reduction in pain perception and experience. Such evidence leads to an increased interest in using AAI in clinical practice. However, it is still not quite clear how AAI works or in other words what it is that makes AAI effective. Therefore, it is crucial to investigate how the inclusion of animals in clinical practice contributes to beneficial therapeutic outcomes.

In this regard, it has been assumed that the presence of an animal enhances the development of the therapeutic alliance, which, in turn, has been shown to play a crucial role in the outcome of the treatment.

However, results from a recent study suggest that a relationship between patient and health-provider alone is not sufficient to influence treatment outcomes, but that a therapeutic rationale is needed and that verbal instructions and suggestions are highly important in shaping participants' treatment expectations.

As placebo effects are related to therapeutic rationale and relationship, the investigators would like to use an expectancy-induced placebo intervention to identify if animal-assisted intervention also works through these two components.

Given that placebo analgesia works well through therapeutic rationale the investigators decided to employ an animal-integrated placebo intervention study with healthy participants (N=128) in a standardized experimental heat pain paradigm. Even though a growing body of evidence highlights the positive effects of animal-assisted interventions until this day little is known about the mechanisms. There exist various hypotheses trying to explain why AAI works, most focusing on the crucial role of the animal in the intervention. However, to the best of the investigator's knowledge there has been no study which examined if the effectiveness of animal-assisted interventions could simply be explained by the power of the therapeutic rational and the relationship. Therefore, it is still unknown if AAI is effective because of the animal or because of its influence on the therapeutic relationship and the given therapeutic rationale.

It is important to understand how AAI works. Moreover, if AAI, like other interventions, is about expectation and relationship, this could have important implications for clinical practice and a better understanding of how AAI must be used to be effective.

If AAI works through similar mechanisms as the placebo, then both interventions should have a similar impact on the outcome of the intervention (reduced pain perception, increased placebo analgesia). Findings of this study could have important implications, not only for clinical practice of AAI but also for intervention in general as the results could help to better understand the importance of these two components.

Inclusion criteria

• Age ≥ 18 years
• Right-handedness

Exclusion criteria

• Being scared of dogs by self-report
• dog hair allergy by self-report
• Any acute or chronic disease (chronic pain, hypertension, heart disease, renal disease, liver disease, diabetes) as well as skin pathologies, neuropathies or nerve entrapment symptoms, sensory abnormalities affecting the tactile or thermal modality
• Pregnancy
• Current medications (psychoactive medication, narcotics, intake of analgesics) or being currently in psychological or psychiatric treatment
• Insufficient German language skills to understand the instructions
• Previous participation in studies using pain assessment with Peltier Devices
• Current or regular drug consumption (THC, cocaine, heroin, etc.)