My Vet Prescribed 400 Mg Of Etodolac , Sig. 1/2-1as

my Vet prescribed 400 mg of etodolac , sig. 1/2-1as needed in 24 hrs., and mention only every other day or every 3rd day for my approx. 60 lb. American dingo,(Carolina dog) about 11-12 yrs old. I cannot find any info on it as far as the side effects as I don't want more problems. He has lost muscle in his back legs, but he still runs sometimes and has trouble getting up and is unsteady sometimes, especially if the other dogs bump him. Is this smart to use?