My rescue Greyhound has tattooed ears (although they are made with a stamp set rather than a tattoo machine). I actually have his reg numbers tattooed on me so we have matching tattoos (although wouldn’t dream of tattooing an animal personally).
I’ve mentioned before that I have pretty much a completely tattooed body, made over a 20 year period. I know pretty much everyone who’s anyone in the U.K. tattoo world and no one decent would do this.
It’ll be done my some unregistered, untrained scrote in his back bedroom.
In some US places they tattoo dogs when unconscious for neutering - these are done to indicate the dog cannot be bred from, to make it less appealing to thieves. Those tattoos are done by veterinary staff, not tattooers.
Anyone who wants this done to their dog for their own entertainment or is willing to do it to a dog deserves to be prosecuted for animal cruelty.
Some years ago there was massive outcry over Wim Delvoye’s tattooed pigs. And rightly so.
Tattoos are for consenting adults only.