Following a routine senior bloodwork/urinalysis, from the urinalysis I learned that my Millie (my 10 year old BC mix) has Struvite Crystals. It is caused by high pH - her is 8.0, and vet prefers to see 7 or lower. Her advice is to put her on a higher meat source/low grain dog food, and check it again in a month. That will lower the pH. I recently had switched from Pedigree (crappy food) to Purina Exclusive (better), but after looking at the review on http://www.dogfoodanalysis.com/ it, too, is higher in grain. So, I'm thinking about switching to Evo, which is rated at 6-Star, and has no grain at all. Question - this is a 42% protein food. Are there any drawbacks to feeding such a high protein diet to a senior? Should be okay if I switch gradually?