One of the primary reasons for the sexual mutilation that most people call "neutering" is to destroy the sex drive as completely as possible. Based on what she's saying, it sounds like it worked as exactly as planned for the OP's dog.
Some dogs will try for a mount/penetration after they've had their balls cut off, but they're rare.
Yeah, yeah, yeah, I already hear everybody getting set to start hollering "But mine does!" Feel free to shut up already. Like I said, they're rare. That's not the same as nonexistent. Winning scratch-off lottery tickets are rare. But a few exist. A mutilated dog is exactly like a scratch-off lottery ticket: The overwhelming majority are "losers" - meaning that as far as mounting and fucking is concerned, they're useless. But every now and then, just like lottery tickets, you hit lucky and find a "winner" - one that will mount and fuck.
Damn near ANY dog will lick - including most who've been mutilated. Nearly every dog who still has his balls will mount and fuck if given the chance. Almost, but not quite, none who don't have balls will even make the attempt to mount and fuck, even with pussy waving under his nose.