Just reading through the reponses to your post, i really wouldnt recomment science plan - i gave it to my westie after recommendation from my vet, and within a week of eating it he was repeatedly sick, diarroeah, and his joints all started to crack in his legs. I took him to the vets and they couldnt diagnose it, they put it down to growing pains!!!!! I thought i'd try changng his food (thought it was odd that it started after he'd started this food). I changed it to James Wellbeloved, as it has no preservatives, additives etc, all natural ingredients, and it all went away in days.
Obviously its your choice, and it may just be my Westie had an allergy or something, but through personal experience, i think Science plan is horrid stuff!