Such disturbances may be of a sensory, physical, intellectual, psychiatric or psychic nature. Tasks a service animal can perform include alerting a person to a sound, guiding a person down the street, pushing an elevator button, retrieving items, alerting other people, or standing guard if a person is having a seizure, or reminding a person to take his or her medication.
On the other hand, emotional support animals are designed to provide companionship aimed at alleviating distress, or provide some other type of relief.

Titles II and III of the Americans with Disabilities Act require service animals to be dogs, although reasonable provisions must be made for miniature horses to serve as service animals when the animals have been trained to perform specific tasks for a disabled person.

It is also important to note that emotional support animals and psychiatric service animals are not the same thing. Where an emotional support animal can be of benefit to people with mental illness, mental health service animals are specially trained to perform specific tasks for people with mental illness. This may include reminding the person to take their medication or to tell someone not to harm themselves.

Laws
Under the Federal Fair Housing Act, housing providers must take reasonable steps to allow people with disabilities to keep a help animal in their home. The U.S. Department of Housing and Urban Development (HUD) requires housing providers to make exceptions to pet rules.
The two conditions required for such an exception are:

The person living with the animal must have some type of disability that severely limits one or more of the basic life functions.
The animal must provide some assistance or assistance related to these identified disorders.

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