These are pretty sturdy for Chihuahuas. Have you tried any of them?
They are all meant for larger dogs, but I find it's best to give a large chew since
there is less chance of choking. Also for bully sticks you can try the braided
ones where there is a couple in one, so it is larger, and if you are still worried
about choking just give it for 15 minutes then replace it with something else just
as valuable and let the bully stick dry out. Your pup is teething and is very
uncomfortable, to help you can also give frozen veggies like carrots or beans,
and you can wet a clean sock then tie it in a knot and freeze it, it makes a
great chew for a teething pup.
Nylabone Galileo Bones Dog Chews | PetEdge.com
Nylabone Durable Dental Dinosaur Dog Chews | PetEdge.com
Nylabone Double Action Revolving Chews for Dogs | PetEdge.com
Nylabone Puppy Teething Rings | PetEdge.com
Nylabone Durable Wishbones -- Dog Dental Chews | PetEdge.com
These are all really great, give them a try!