Why is my male chihuahua humping my female chihuahua?

why is my male Chihuahua humping my female chihuahua.
she came into heat and I found them stuck together 3 weeks ago so im pretty sure shes pregnant so today he just started humping her like crazy he wont leave her alone

Hi,

When a female dog is in heat, it emits hormones that attract male dogs. This will initiate breeding which is their way of reproducing and continuing their species...

You're likely to have a litter of pups on your hands now. Which you will need to find homes for. It's irresponsible for a pet owner to not spay/neuter their pets and then act surprised when they breed. I'm not sure what you expect...

Life is like that to, we are suddenly become attracted to each other!

well if she is still in heat that is probably right because a male dogs smells when a female dog is in heat and he gets attracted to it.

they are breeding. duh!!

Maybe cause he's a MALE and she's a FEMALE. Or it could just be cause your female is in heat.

I understand your confusion...I thought when they bred once they wouldnt do it again (and again,and again, and again)during the same heat cycle.But they do!I guess to ensure the continuation of the species.Sometimes they dont get pregnant the first time.