Joe, Wilfried, thanks very much for replying to my request!
"The metre of 10/8 is very, very unusual in German folk music. Did you hear right?"
My grasp of metre is not great, but I'm sure it is either 10/8 or 5/4- certainly not 3/4, 4/4 or even 7/4, for example. The melody as I remember it is quite jaunty with a major/Lydian feel.
My mother (who's from Swabia) believes that 'Kat' is a shortening of 'Katharine', and therefore has no feline associations. Thank you for the Bavarian tip - I'll keep searching...