Yes it would be to great a risk with the diffuser.
Like you , I learnt to recognise the early signs. With kim , it was her wees getting slightly smaller in her litter tray .

We have two cats, so I'm glad that Pooks begins drinking more instead of her wees getting smaller. With two cats, you have no idea whose is whose unless you're looking extremely closely and still it's hard. I'd not see it coming and she'd be in more distress than she needed to be. We keep two litter pans. One closed and one open... but they still use both randomly.

Universal male behaviour !

I've always lived in a multi species pet environment and from that I've learnt how important the initial introductions and the first few days are especially with cat meeting cat .
That is often a disaster! If they get off on the wrong foot its very hard to undo the damage.

Impossible to undo it, usually. We had to give a cat away partly because of this. There were vicious and severe injury inflicting fights and eventually enough was enough and the cat was given to a country man where he could be a farm cat. The females we've had never fight with each other badly, though the dislike is still there.

Funny how they can establish the pecking order among themselves. Our Alpha male of all the creatures is Levon. Nothing imposing about him and he must weigh around ten pounds. But he is the top cat. However Stumpy is another story. She's a stumpy Manx and from kittenhood has played so rough no one will join her. She and Levon seem to keep a respectful distance. It's good when they somehow work it out.

Lovemybull,
How many cats do you have?
I miss having a cat more than anything. I miss the purrs and the chin rubs and kisses.
I'm also known as kimthecat on most forums but felt it might be more appropriate to call my self Dibbythe dog on a dog forum.