There are many reasons spending time with animals helps improve mental health. According to Christian Health, spending time with animals helps our bodies release serotonin, prolactin, and oxytocin. These are all considered "happy hormones" which help block out depression. People who suffer from depression and anxiety often have loss of purpose. Having an animal that depends on you gives you purpose each day. Animals are used in many hospitals, nursing homes, and physical therapy facilities to provide patients and residents with companionship.
It is crucial to keep stress away from animals in shelters as much as possible. Putting an animal into an enclosed area where they are not comfortable, can trigger animals stress responses which can cause them to act aggressively. Animals have similar reactions to humans when it comes to stress. If they experience trauma or long term stress, it is hard or even impossible to move on. That is why it is so important for animals to be fostered. It gets them away from a stressful environment and allows them to decompress and relax. It provides them with a safe place to learn how to be comfortable with people again.