Biochemical and Physiological Benefits of Animal-Assisted Therapy

Berta Garrido Zabala

As stated by A. Katherine et al (2010), animal-assisted therapy (AAT) is an alternative type of therapy that uses animals as a treatment method. AAT is one of the multiple animal-assisted interventions (AAI), a term that was defined by Beck and Katcher (1984) in order to distinguish the emotional response to animals within various contexts, i.e leisure and entertainment from therapy. These terms are often confused since animal assisted therapy is commonly used to define activities that do not fit into the scientific definition of therapy, i.e “the medical treatment of disease; curative medical or psychiatric treatment”, as defined by Oxford English Dictionary (1997). 

Animals are considered to be a multi-sensorial stimulus. By their own nature they include the elements of movement, sound, smell, texture, warmth and a physical tactile sensation that automatically awakens all of a person’s senses. They are a living and unique stimulus that provokes interest in people and thus they are optimal in several therapies. The type of animal that is used in AAT depends on the specific therapeutic program. Even if dogs are the most widely used animal for AAT, other animals such as horses, cats, guinea pigs, dolphins, fish, and even birds can be used. Although dolphin-assisted therapy does not currently have much support from scientific studies and more studies are required, the benefits of dog or horse-assisted therapy are strongly supported by the scientific community. 

The overall benefits that ATT provide include biochemical and physiological changes such as an increase of what can be defined as the biochemistry of well-being. Physiology is defined as the study of the overall properties and functions of the organs and tissues of the body of living beings. The main physiological changes that we will describe as benefits of AAT lead to an improvement of the motor functions of the organisms. Moreover, psychological changes such as a decrease in the feeling of loneliness, relaxation and an increase in self-confidence as well as self-trust can be observed in patients. 


In order to analyze the effects of AAT on depression, the Beck Depression Inventory (BDI) is commonly used. BDI is a 21 self-scored analysis that has been widely used in depression research. BDI studies feelings of sadness, self-worth, and  ideas about future goals. Another test that is performed in these studies is the Beck Anxiety Inventory (BAI) that is commonly used to measure symptoms of anxiety since depression and anxiety are often associated with each other. Commonly, after animal therapy is performed, the results of BDI studies are better. Patients who have undergone AAT claim that after therapy their depressive symptoms have significantly decreased. This is due, among other factors, to the curiosity triggered by the animal-contact, the build-up of empathy and above all, they confirm that it is because their full attention is not focused on themselves but on the animal that accompanies them. (An example of BDI can be found here.)

Moreover, regarding the biochemical effects, a study performed by J.S.J. Odendaal (2000) showed that the levels of neurochemicals and hormones change during human-dog interaction. The parameters were measured after an interaction between 5 and 24 minutes.  For their study, blood samples from the patients were analyzed. The levels of various molecules such as  β-endorphin, oxytocin, prolactin, phenylacetic acid, dopamine, and cortisol were examined. These molecules are well-known positive and happiness associated neurochemicals except cortisol which is related to stressful situations. The results showed how in both humans and dogs all the positive chemicals were significantly increased. Additionally,  in humans, the cortisol levels were decreased compared to the initial situation. These results also demonstrated that AATs performed with dogs do not have negative effects since they also yield the production of happiness molecules.  Moreover, a general decrease in the mean arterial blood pressure (MAP) was observed. The biochemistry analysis confirmed the positive relation between human-dog interaction during therapy. The increment of these molecules is associated with well-being. Future studies have been conducted over the years confirming the physiological effects that benefit from AAT, information that has been well known for more than twenty years. 

Similar results can be observed in patients suffering from post-traumatic syndrome (PTSD). However, there are still situations where these effects cannot be generalized. In the case of dementia an initial improvement is observed, but the effect is usually lost after three months. Regarding schizophrenia, although it seems that there are improvements in the quality of life and well-being, more scientific studies must be carried out in order to conclude that AAT has a benefit in the patients. 

Image 1 Unsplash

Multiple sclerosis

In the case of multiple sclerosis, horse-assisted therapies are widely used, also known as equine-assisted therapies (EAT). EAT has been shown to have benefits in terms of balance and the development of patients’ motor skills. In the study performed by Hammer et al (2004) physical tests included balance, gait, spasticity and functional strength among others. Balance was measured using the Berg balance scale. It consists of 14 different tasks in which the patient has to maintain a specific position. Gait was analyzed by a 10m walking test at max speed. Spasticity was tested using the modified Ashworth scale (MAS) where the different flexors and extensors of the body were studied. Functional strength was measured by two aptitudes of the Index Muscle Function (IMF) which included bending the knees up to 90 degrees and the ability to step up onto a step. The results of this study showed that balance was the physical variable that showed a bigger improvement, although all other variables also showed an overall gain. Overall, these results demonstrate that EAT contributes to the improvement of the patient’s motor skills. The study by Hammer et al is supported by further studies showing that EAT clinically improves the quality of life of patients with multiple sclerosis. EAT has also shown benefits regarding stroke patients and spinal cord injury patients since the improvements in the motor impairment are acquired. 

Image 2- Itaca and me (My photo from my blog

Finally, it can be said that in almost all situations it has been observed how interactions with animals improves our quality of life. Although in many cases this conclusion is supported by multiple scientific studies, it is true that in other situations more research has to be done. However what is clear is that we are fortunate to share this world with incredible beings that not only accompany us but also help us achieve our well-being. They are motivators from whom, without a doubt, we can learn many things about life.

Sources: Good therapy, Healthline, Scientific articles