As you know, Smoke and Pepper went in Monday and got neutered. I picked them up yesterday and everything was fine. Last night, all of a sudden, both of them started humping everything in sight. They never used to do this. Twiggy is in heat and is in her crate on top of the tv stand. Pepper ignored her pretty much before getting neutered, but last night starting at about 10 pm and lasting all night, he whined and cried and tried to get at her. Is there a surge of testosterone that happens when they are neutered? I don't remembering this happening when I got the others neutered, but Twiggy wasn't in heat at the same time either.