"The mother had gotten hit by a car, and, unfortunately, she passed away when he was just two days old," said Faith O'Georgia with the Michigan Humane Society.
Photo Gallery: Orphaned puppy adopted by mother cat and litter of kittens
Since Bobby was left an orphan, MHS staff decided to take a chance with Gwen, a mother cat who was already nursing a litter of five kittens.
Gwen accepted Bobby as one of her own -- feeding and comforting the pup along with his kitten siblings.
"They're pretty young, so they're growing into their personalities," Ryan McTigue, of the Michigan Humane Society, told ABC News. "After he's big enough, we are going to get him in foster care among dogs, so he can learn to be a dog. He'll be a good ambassador for both species, that's for sure."
The human society posted a video of Bobby and his blended family onto their Facebook page on Friday.
More than 62,000 people have viewed the video and many have inquired about adopting the animals.