Good afternoon, We purchase puppies and raise/train them as service dogs. Each puppy is entered in as a unique piece of inventory that is for sales. I would like to allocate the pups food expense and other vet bills to that specific pup so when we sell it I can see the profit margin for that specific pup. How can I add expense to an item already set up in inventory. 

For example

Luke is an inventory item, he is entered in at the purchase price we paid for him.

HIs food and vet bills I was previously posting to COGS but I would like his portion of the food to be added to his cost monthly. How can I do this?