For what it’s worth, my vet said he just returned from a conference and the most recent information about the length of time to feed a single protein to see if a cat’s itchiness is caused by food allergies/sensitivities is 13 weeks. He said 84% will show an improvement after eight weeks but if you continue to feed a single protein for five more weeks, that jumps to more than 90%. I apologized that I can’t remember the latter number but it might have been 96%. I thought I would pass this along for people to keep in mind.