I am seeking the half life of Rimadyl chewable for a 70 lb dog 15 years old who is rx'ed 150 mg per day. There are some days with his other pain meds he may need less. I am seeking the half life on the following mg's: 50mg, 75mg, 100mg and 150mg.

My vet and every article I read just seem to hem and haw not giving me the exact 1/2 for each mg. If I need not give a full 150mg I rather not.