Mounting

Question
Hi!
I have a 6 year old Long Haired Chihuahua (Male). I just recently got a new Corgi Puppy (Now Five Months & Female). One day I noticed she was circling him & rubbing up against him. Then, he started sniffing her genical area. He in return, sniffed his too. After that, they shared a growl. He then mounted her. He usually fights with her, but today they got really sexual. She is in puberty. Any suggestions? Is her sexual hormones coming out?

Answer
Hannah,
A female can come into heat anytime from 4 months on.  You might want to separate them or neuter your male or spay the female, because the corgi is too young to have puppies.
It could also be a dominant action on your male's part.  The rubbing could be a submissive part on the corgi's part.  Either way, be careful, watch that she is not showing any bleeding or other signs of heat like a swelling vulva.  When you say that things got sexual, did he enter her and tie?  If so, you should get her to the vet and ask his advice on whether she should be spayed or given a shot.
Nancy