Minimally conscious states, which occur after severe brain injuries, represent a significant
burden and can lead to long-term disability. Patients in minimally conscious states are a vulnerable
patient group that needs early and effective treatments. Animal-assisted therapy is a possible
treatment for minimally conscious patients and is applied for various reasons. The stimulation provided
by animals is multisensory and emotional. Interactions with animals function nonverbally, and these
situations are easy to understand. First studies have shown that animal-assisted therapy can increase
active movements, awareness, and brain activity. However, the evidence base for animal-assisted
therapy in treatments of minimally conscious states is minimal.
We conducted three studies to better understand the effect of animal interaction on minimally
conscious patients. First, we wanted to investigate how animal-assisted therapy affects behavior,
physiological parameters, and the level of consciousness of minimally conscious patients. For this
purpose, we conducted a randomized two-treatment multiperiod crossover study that measured
patients during eight animal-assisted and eight conventional therapies (study I). Second, we were
interested in the mechanisms involved in the interaction between minimally conscious patients and
animals. For this purpose, we measured brain activity in two experimental studies with healthy adults
and minimally conscious patients (studies II and III). We compared the responses to different forms of
contact with a dog and a plush animal. We also analyzed patients’ heart rates and heart-rate variability
in study III.
The crossover study revealed that the minimally conscious patients showed more behavioral
responses, more awareness, and higher physiological arousal in the animal-assisted therapy sessions
compared to conventional sessions (study I). Healthy participants in the experimental study showed
higher brain activity when interacting with a dog than with a plush animal. The closer the interaction
with the dog or plush animal was, the higher the brain activity became. Minimally conscious patients
also had increased brain activity with increased proximity to a dog or a plush animal. But the patients
reacted equally strongly to the dog and the plush animal. However, the patients’ heart rates were
higher during interaction with the dog than with the plush animal.
The three studies indicate that interactions with animals have the potential to arouse minimally
conscious patients physiologically and emotionally. This arousal allows these patients to participate
more fully in therapy through a higher level of consciousness. The three studies make an important
contribution to better understanding the influence of animals on minimally conscious patients.
However, one of many new questions is how animal-assisted therapy should be delivered and which
patients can benefit most from this therapy approach. More studies will be needed to enable a safe,
evidence-based application of animal-assisted therapy in minimally conscious patients
