Sudden mounting

[Whimsy]

I've had my two guinea pigs for over a year and a half now and they have gotten along really well from the beginning. Melvin is a male and Mila is a spayed female. Two months ago I moved to a new place and the first night it was like they had to rediscover who was the boss and there was lots of mounting attempts from Melvin and Mila getting annoyed. It only lasted one night and they were back to normal after that.
Today it started again. Melvin is chasing Mila around the cage and tries to mount her and she is squealing and getting annoyed. I wonder why he is suddenly doing this and what I can do about it? I would really appreciate any advice I can get.

[3piggles]

The move issue makes sense, as any major change to their environment is reason to re-establish dominance. Why he's doing it now, I don't know. There are some possibilities, and all warrant a trip to the vet as soon as possible.

If she has a health problem and is weakened, he could be mounting to show dominance, not for sex. If she's squealing, she could be in pain when he mounts her, which implies a health problem.

If he's mounting because something about her tells him she's in heat, she could have a cyst or a tumor that's creating a heat-like scent. Again, vet visit, soon.

Try getting her out of the cage and on a flat surface, and gently stroke, press all around her back and hind area. See if she has a bad reaction such as crying, turning her head toward you quickly as if to bite, etc. If so, she's in pain or discomfort, and should be separated from him until the vet can figure out what to do. Good luck!

[Whimsy]

Thank you. He stopped doing it last night and hasn't done it today either, but I will definitely check her out and see if something is up.