Where in Sweden have you ever heard someone pronounce 'katt' anywhere close to 'cut'? Maybe you misheard someone say 'kut' (baby seal)?
cut - IPA(key): /kʌt/
https://en.wiktionary.org/wiki/cut#Pronunciation
katt - IPA(key): /ˈkatː/
https://en.wiktionary.org/wiki/katt#Pronunciation_3
(there's audio on both links)