If the wife is into spanking as a form of sexual activity, I think that falls under the category of sex not under corporate punishment. If the spanking is consensual, then I guess it is not abuse. If it is not consensual then it is abuse. There is a scene in Handmaid's Tale where Commander Waterford spanks Serena with a belt (she was fully dressed) for disobedience, it was horrific to watch. Even though I doubt this spanking caused a lot of physical harm, I think it is definitely abuse. If the wife consents to corporal punishment, I think it is still abuse.
Just because someone feels slightly aroused during abuse doesn't means she wants it. This is the manipulative language abusers use to convince their victims they wanted it (or that it wasn't abuse).