I used to give 81mil coated aspirin to my dog and it was OK at first then it started to upset her stomach.Baby aspirin did the same thing and didn’t seem to help her.
I found Joint Maintenance by Hartz and it has been wonderful for her.It comes in two strengths according to your dogs weight.
Any store that carries pet supplements should have it . I get mine at Wal-Mart.It is more costly than aspirin but worth the $8 a month to me.

If you google “aspirin dosage for dogs” you can find what dosage to give them by weight. I give it to my dog after he has vaccinations and his leg gets a little sore (although I think he milks it just a little because he knows I’m a sucker) and it really seems to help. I crunch it up and put it in a spoonful of kinda melted Frosty Paws.

I have given mine baby aspirin, 1/2 tablet 2x daily. Clucosemine-Chondroitin is wonderful for older dogs. It helps to lubricate the joints giving them much relief! You can get Glucosemine-Chondroitin at your local pet supply store. It is a bit more costly than baby aspirin but well worth it!

I would ask a vet to know for sure. I just found out that chocolate and cat food can kill a dog. They are much more sensitive to things than I thought. Your Terrier is getting old ( I know it’s hard to hear that) so I would get the doggy pain relievers so it can live out the rest of its life more comfortable.

Ascription can be used for dogs. It is just aspirin with maalox to protect the stomach lining. For a Boston, I would start out with only 1/4 of a tablet. I would not give over 1/2 tablet as a dose.

It acts as an antiimflamitory