I'm afraid so. Cats can digest milk, but dogs can't. I can't remember the exact problems caused by dairy, but I can look it up, if you'd like? I think I will, just to appease my own curiosity. Will post it in a few. But I'm afraid I would advise against letting your dog having the cereal milk. I'm sure he won't understand when she stops giving it to him, but perhaps you could provide a substitute for a while, then slowly wean him off that as well, to teach him not to expect anything after your wife finishes her cereal?