Many charities help to train and provide trained dogs for people who need them. Not everyone can afford to purchase one of these very special dogs. Other organizations help people learn about assistance dogs, and protect the laws allowing people to benefit from this medical option. 
For more information, contact these organizations:
Delta Society: The
International Society of Service Dog Partners www.iaadp.org
Keystone Human Services www.keystonehumanservices.org
Guiding Eyes for the Blind www.guidingeyes.org
Working Like Dogs www.workinglikedogs.com