Hey Dee,
Sorry it's taken so long to get back to you, I've been in Kentucky since last week. If Kato is still itchy I would definitely go to the fish. Just cut him back some. Sash is 70# and gets about 2 cups a day on Blackforest, about 1 3/4 on Ocean Blue. If he gets a little too pudgy add ground veggies.
Jessa,
It sounds like it's anal sacks to me. The only time my dogs lick their butts is when they need to be expressed, that or they do the carpet drag. Ugh. Do they get raw bone? That will sometimes help the anal glands empty on their own.
