When I stroke my cat, instead of her coat feeling smooth, it's full of numerous large clumps of hair. It started this summer, and it's gotten worse. She has become thin and frail. She's a 100% outdoor cat by choice. Last summer, I used Advantage Multi on her twice. Two weeks ago, I gave her de worming medicine (piperazine). Has anyone on the forum experienced this? Does anyone have advice about the possible cause and treatment?