what impact does the extended dog metaphor have on the tone of “reunion”?

I'll post parts of the story that used the dogs as metaphors.

"He chuckled as their muffled noises reminded him of whimpering puppies down at the animal shelter where he volunteered. Puppies always seemed to make noises as they played and whined for attention from the older dogs or volunteers. He liked working in the smaller dog area where all the older dogs looked out for the puppies, just like family, just like his family of older members looking out for the younger ones."

The metaphor of the dog gave me a clear picture of what their family is and how they act towards one another.

Their family is big in number and most of them are kids. They are a boisterous bunch and they enjoy each others company just like puppies. The older batch of cousins are like the big dogs that keep watch over the younger cousins like puppies. 

Their family is big, happy, warm, and clearly enjoys each others company.