mating when not on heat

Question
am puzzled. i have a gorgeous 10 month old tenterfield terrier cross jack Russell. she came on heat around the beginning of February. after the three weeks she was on heat for, i kept our housemates jack Russell away from her for another 2 weeks after she'd finished her heat as a precaution. they however still 'had a go' and got stuck together. i rang the vet and they told me it is possible she could be pregnant. i calculated it and she is due on 19th May if she is indeed pregnant. two days ago 22/4 however, i walked outside to find they were stuck together. i thought that dogs only got the urge to mate when they were in season! could she fall pregnant even if she is DEFINATELY NOT on heat?? and if she is pregnant from the first time they tied, could this be harmful in any way? I'm confused ..please...any help would be greatly appreciated.

Answer
Hi Emma

She can only become pregnant when she's ovulating so when she's in heat.

There is a number of reasons she is standing for a male,  split heat, false heat or she has an infection that is causing the male to think she's ready.

Regardless, I would take her to a vet and have it checked out.

Good luck.