The actual bug here was a mistake in handling of liquid volume. The cats were ingesting a tankard’s with with each lick, and they’re smaller than dwarves, so that killed them.

I read about a cat who used to visit a pub and learned to lick beer from under taps. The cat got banned from the pub for its own good but I don't believe it was anywhere close to poisoning.

Do you have a source for this?

No, I read this a long time ago in a paper press article and I cannot dig up anything electronic.