Do you beat your kid when he writes on his little sister with a Sharpie too?
This is stupid and immature, not cruelty. Natural oils will break the Bond between fur and ink with no harm.
And actually difficult to believe. I bred 1 litter of german shorthaired pointers. Breed standard calls for tails to be docked at 3 days old. The night previous to taking them to the vet to have tails done I carefully marked in black sharpie pen where the tails were to be docked. The next morning I went to the whelping box to check on everyone and mom had completely licked clean every speck of ink.
However, cats regularly cleanse themselves by licking their coats, so they could ingest the ink.
well, I guess I’m stupid too, because I’d shoot the little bastards who did this.