Bests & Worsts Reviews from Amazon

I had 8 cats 6 weeks ago, and as of last night, I have 6. I believe Blue Buffalo killed 2 of my 11 year old cats (that were brothers). After slowly transitioning them to this brand, that it supposed to be superior (and very expensive), everyone seemed to love it. I mixed it half and half with Blue Buffalo Basics Duck & Potato Recipe. They loved it--I purchased more. 3 weeks after beginning to feed them this, one cat died of acute and sudden liver failure 6 weeks ago - otherwise a perfectly healthy indoor male cat. Last night (6/18/18), his brother all of a sudden couldn't walk, and died 2 hours later--blocked urethra. Also an otherwise perfectly healthy indoor male cat. They are all drinking a lot of water, so I feel in my heart that it's this food. Plus, I've give them purified water since they were babies. Feeding them Blue Buffalo is the ONLY thing I've done different in 11 years. Hopefully this can get out of their system before I lose another one. I am heart broken and devastated. Back to Purina One for my babies. I just hope it's not too late.