Horsepower - The Effect of Equine Assisted Therapy on Military Veterans with Post-traumatic Stress Disorder

Existing literature suggests that animal assisted interventions (AAI) could
positively affect the welfare of veterans diagnosed with PTSD (O*Haire et al.,
2015), but recent research has mainly focused on the use of specially trained
PTSD service dogs (reviewed in van Houtert et al., 2018). A relatively new type
of therapy is equine-assisted therapy. Although the limited number of studies
published on this subject does suggest a positive effect, hard evidence of the
effectiveness of equine-assisted therapy on veterans diagnosed with PTSD is
lacking. Most existing studies have used a large variation of questionnaires or
interview techniques to measure the effect of equine-assisted therapy on PTSD
symptoms. Although these studies might provide promising results, in this
feasibility study we want to know whether the effects that have been found in
previous studies can also be measured in the human body using objectie
measurements.
Additionally, the already existing studies use different methods of working
with horses, so the exact content of equine-assisted therapy that could cause a
decrease in PTSD symptoms is unclear. Whereas some studies suggest that simply
interacting with the horse can create positive effects, other studies claim
that riding is a crucial part of the therapy (Johnson et al., 2018).
Finally, the physiological and behavioural responses of the therapy horses are
underexposed in existing research. It is important to look at the responses of
the horses, as it is suggested that the mental state of a rider has an effect
on the physiology and behaviour of the horse (Nuyts, Exadaktylos & Berckmans,
2013). This means that there might be a relationship between the responses of
the veterans and the responses of the horses, for example increased oxytocin
levels in both veterans and horses during positive interactions. As a
consequence, the responses of a therapy horse during a session might reveal
something about the mental state of the veteran.
This feasibility study will therefore investigate objective welfare parameters
that could be relevant for investigating the effects of group therapy with
horses on military veterans diagnosed with PTSD. This feasibility study
hypothesizes that objective welfare parameters can be measured in veterans with
PTSD symptoms during participation in the 12-week therapy program.

The primary objective of this feasibility study is to measure objective welfare
parameters (HRV, salivary cortisol and oxytocin and stress related behaviour)
that are relevant for studying the effects of therapy with horses on veterans
diagnosed with PTSD and to investigate if they correlate with subjective
validated welfare parameters (questionnaires).
The secundary objective of this feasibility study is to investgate whether or
not therapy with horses leads to an improvement in the quality of life of
veterans that are diagnosed with PTSD. Quality of life will be measured using
16 objectives, which are related to PTSD symptoms.

This feasibility study will have a purely observational design using
non-invasive measurements and questionnaires. Participants participate in one
therapy session per week for a total of twelve weeks. Sessions take place at
the location of Stichting Bio, which is located at Wekeromseweg 8 in Arnhem,
the Netherlands. Each session starts at 10:00 and finishes around 15:00. In the
morning the participants get an introduction and theory on how to work with the
horse. After a joint lunch, the participants are going to work with the horses
in pairs. At the end of the day there is time to reflect, share experiences and
give feedback to each other. This session will be recorded using an audio
recorder, so that the research team has the possibility to listen to the
feedback and experiences of the participants afterwards and use these in the
analysis of the resuts.
Heart rate measurements and saliva sampling will be done each week before,
during and after working with the horses. Additionally, participants will be
asked to take a saliva sample the evening before the session and bring it to
the session the next day. Two out of the four questionnaires will be filled out
each week after working with the horses, the other two questionnaires will be
filled out once per month. 12 weeks after the last session the participants
will be asked to come to Stichting Bio for a follow up measurement, in which
they fill in the questionnaires for the last time.

The only risk that is associated with participation in this study is that the
participants will work with horses. However, the horses that will be used for
this feasibility study have experience with working with children with physical
handicaps, which means that these horses are very calm and reliable. The chance
that these horses will startle is therefore very low. Additionally, experienced
supervisors will be present, who can intervene at any time if necessary. The
intended benefit in terms of a decrease in PTSD symptoms and improved quality
of life will therefore outweigh the small risk that is inherent when working
with horses. As the veterans will only have one therapy session per week, it is
expected that the burden associated with participation is relatively low
compared to the possible benefit.