From today's WAD; another version has the added couplet as noted:

There wanst was two cats of Kilkenny
Each cat thought there was one cat too many
So they fought and they fit
And they scratched and they bit
'Til except for their nails
And some bits of their tails,
instead of two cats there weren't any."

Torture of animals used to be very common at fairs, etc. And the practice of tying two cats' tails together ane hanging them on a line was very common. No clue as to how Kilkenny became name for it. I can still remember hearing about people staying at a gathering "until the last dog was hung".

Thank goodness the shameful practice is rare now.