The Homeless Guy and his Dog

A couple of months ago, I saw a homeless man and his dog standing by a freeway entrance with a sign saying he needed food. I pondered the situation as I looked at the loyal dog who was completely dependent on his master to get him food. Of course, the dog could run away and fend for himself. Or he could wait with his master and hope that the master would provide food for both of them (which is what he was doing). I wondered how valuable the dogs loyalty and companionship was to the master. What percentage of donated food would the master not eat himself and instead give to the dog? And at what point would the master just send the dog away.