الفهرس 
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Abstract
Dogs were domesticated from gray wolves about 15,000 years ago. They must have been very valuable to early human settlements, for they quickly
became ubiquitous across world cultures. Dogs perform many roles for people,
such as hunting, herding, pulling loads, protection, assisting police and military,
companionship and more recently, aiding handicapped individuals. This impact
on human society has given them the nickname ”Man’s Best Friend” in the
western world. In 2001, there were estimated to be 400 million dogs in the world
(Coppinger, 2001) and (Spady and Ostrander, 2008).