Hair Cortisol in Service Dogs for Veterans with Post-traumatic Stress Disorder Compared to Companion Dogs (Canis Familiaris)

ABSTRACT

Service dogs are trained to assist humans. This assistance potentially exposes them to stressors To investigate if service dogs are exposed to more stressors than companion dogs we questioned whether hair cortisol levels differed between both groups. We studied this by cutting a tuft of hair from the neck of 19 companion and 11 service dogs. Cortisol levels were subsequently analyzed via immunoassay and compared via a simple linear regression model. The influence of coat color, season, sex, other dogs, pets, or mental health diagnoses in the household was also checked . Results showed that cortisol values did not differ between service and companion dogs. Furthermore, none of the additional variables had an influence on cortisol levels. This lead to the conclusion that the service dogs in this study did not have higher hair cortisol levels than companion dogs Further study should be conducted as to why no difference did occur between groups and if this difference is persistent over time given that we only studied a period of up to two months’ worth of hair cortisol.

KEYWORDS:

• Service dog
• PTSD
• cortisol
• hair

Acknowledgments

The authors of this study would like to thank every individual who contributed to its realization. We would especially like to thank Stichting Hulphond Nederland, the Dutch Ministry of Defence and the Nypels Tasns Fund for PTSD for supporting this research. Additionally we would like to recognise the efforts of Susanne Kirchoff in the analysis phase of this study.

Data Availability Statement

The data presented in this study are available on request from the corresponding author.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Institutional review board statement

Ethical advice regarding the procedures performed in dogs in this study was sought from Utrecht University’s Animal Welfare Body. This Body can be approached with the question whether the experimental animal work requires ethical approval. Because no invasive measurements were taken however the Animal Welfare Body communicated that the procedures performed were not considered an animal experiment and that the protocol of this study did not require further ethical approval (decision taken on November 27 2017).

Ethical review and approval of the questionnaire used in this study was obtained from the medical ethical committee of the Utrecht Medical Centre, Utrecht, The Netherlands. This approval was part of a larger study to the interaction between service dogs and military veterans which is covert in dossier NL64117.041.18. The procedure to acquire data additionally included informed consent of the participating veterans.

Additional information

Funding

This study was funded by the charitable donations of the Karel Doorman Fund, the Utrecht University Fund, Royal Canin, the Triodos foundation, the K.F. Hein foundation, and Stichting Vrienden Diergeneeskunde