Green’s Dictionary of Slang

(Irish) the left hand, a left-handed individual.

1825		Pierce Egan’s Life in London 28 Aug. 243/2: [Irish speaker] How I came [to be] caught be there with a glass of the real stuff in my kithogue, this gentleman [...] will tell you.
1922		Joyce Ulysses 408: the children Kithogue! Salute! the idiot(Lifts a palsied left arm and gurgles.) Grhahute!
2021		Trip Advisor Irish Slang 🌐 Ciotóg- A left handed preson (Irish- Kithogue).