my chocolate lab used to get an asprin a day for her arthritis; i made it a pretty special treat...i would put a gob of peanut butter on a ritz and hide the asprin in the peanut butter...it was her favorite time of day. :-D
if the asprin is for arthritis ... there are other suppliments available in pet shops (like petsmart) specifically for joint pain relief that is better for your dog...and the dosage is based on weight.
i checked with my vet before giving my dog any asprin. one dog could not have asprin...my lab could. a test for liver function is recommended before an asprin regiment