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 (for example
Malinowski et al., 2018), 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 (Johnson et al., 2018, Malinowski et al.,
2018), in this 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.
This study will look into the effects of 12 weeks of grouptherapy with horses
on military veterans that are diagnosed with PTSD. With the use of objective
as well as subjective measurements in veterans and horses this research will
investigate whether this form of therapy leads to a decrease in PTSD symptoms
and thus an improvement in quality of life of these veterans. The hypothesis of
this research is that veterans will experience a decrease in PTSD symptoms and
thus improved quality of life after participation in the 12-week grouptherapy
program with horses.

The primary objective of this study is to measure to what extent a 12-week
grouptherapy program with horses leads to an improvement in the quality of life
of military veterans that are diagnosed with PTSD. Quality of life will be
measured using the following 16 parameters, which are related to the symptoms
of PTSD;
• Change in cognition and mood
• Change in feeling bad about yourself
• Change in feeling guilty
• Change in not being able to trust anybody
• Change in feeling that the world in dangerous
• Change in feeling that the nerve system is destroyed forever
• Participation and interest in activities
• Collaboration with other people
• Feeling positive
• Experiencing satisfaction
• Experiencing happiness
• Finding a purpose / meaning in life
• Having a prospect for the future
• Sleep disturbances and insomnia
• Flashbacks / nightmares
• Stress levels

This 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 Stal Groenendaal, which is located at Zevenhuizerstraat 154 in
Bunschoten-Spakenburg, 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 this interaction each participant
will have 15 minutes of free interaction with his or her horse. During this
free interaction participants can make a connection with their horse in any way
they want to. After the free interaction participants receive a joint lunch.
Thereafter, the participants will have a directed interaction with their horse.
During this directed interaction they will have a different assignment each
week. The first weeks the assignments will be taking care of the horses and
doing grounwork with them, for example letting the horses walk over obstacles
such as a plastic sheeting. The last three weeks the participants will also
ride the horses. After working with the horses there is time to reflect, share
experiences and give feedback to each other.
During the day heartrate of the participants will be measured using a Polar
m430 watch. This watch is linked to a Polar H10 transmitter, which is placed in
Hylofit electrodes that are attached to an elastic band that is placed around
the waist of the participants. The Polar watch and transmitter will save heart
rate data of the participants, which enables the researchers to investigate
differences in heart rate during the sessions with the horses as well as over
the 12 weeks. Besides, participants will wear a small bag around their waist.
In this bag an Actigraph GT9X accelerometer is placed, which registers the
activity of the veterans during the session with the horses The researchers
will link this data about the acitivity of the participants to the heart rate
data, so that they can determine whether particular increases in heart rate are
attributed to physical effort or to mental tension or stress.
Additionally, saliva sampling will be done each week before and after working
with the horses in the morning and afternoon. In total four samples will be
taken every week for each participant.
Both the free interaction in the morning and the directed interaction in the
afternoon will be filmed using Oppo A5 (2020) mobile phones. These mobile
phones are limited in such a way that they can only be used for filming. The
phones do not have access to the internet, and it is not possible to watch the
videos directly on the mobile phones. The videos are only saved on Yoda, which
is a protected drive that is used by Utrecht University. The videos will be
observed in the program Observer XT 12 in order to observe stress related
behaviour in veterans and horses. In order to get their permission, the
participants have signed a form before the start of the intervention in which
they agree to be filmed (see document E2).
Finally, each week the participants will fill out questionnaires. Two out of
the four questionnaires will be filled out each week, the other two
questionnaires will be filled out once a month. 12 weeks after the last session
the participants will be asked to come to Stal Groenendaal for a follow up
measurement, in which they fill in the questionnaires for the last time. One of
the questionnaires that will be used is the PCL-5 questionnaire. This
questionnaire will also be filled in monthly by a waitlist control group of 24
veterans.

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 study 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.