I don't know what it is, but my 8 month old Lab/ Whippet, Molly just LIVES to chew. Rawhides, stuffed bones, any of her toys... basically anything she can wrap her paws and teeth around! We have been lucky, so far
she hasn't gotten into chewing up shoes or any of our stuff. But she sure loves to chew on sticks. Even when we are out walking, if she finds an especially delicious looking stick in the woods, she will stop to chew on it.
I have heard good and bad things about chewing sticks. Do you let your dog chew sticks? I think I would go broke if I always had a rawhide or other toy for her to chew on instead!!!