I was wondering what the problem with the dog was....
But from Gill'sremark I understand the dog is new, and was introduced at a time that was already difficult for Ziggy.
If so, it wasn't a very clever move, to put it mildly... When a cat is ill or recovering, and therefore under stress as things stand, is just about the worst time to have any changes, let alone bring in a new dog, of even a new cat.
Even if Ziggy hadn't been ill, the decision about taking a dog would need very careful consideration. One would first have to test if the cats would accept one, and if that particular dog would get on with the cats and vice versa. If not, the cats come first. Cats rule.
You simply cannot expect a cat, even a healthy, unstressed cat, to accept just any dog you decide to get and be his normal self. A dog, like a human, is a cat's empoyee. If you want it to work, the cat has to show he is willing to share his house with the dog. Ziggy is clearly stating he doesn't want this dog invading HIS house and claiming HIS slaves.