My dog might be pregnant

Question
Hi i feel abit silly asking this question but my female jack russel came into season around 6weeks ago. We were moving house at this time also, The day of the move my Aunts male king charles cavalier managed to mate with her, she was still slightly bleeding. They were stuck together but only the once. Recently she has started to go off her morning meals which is very unusual for her and i've noticed some weight gain around her abdomen!
Im guessing more than likely she is pregnant but do you have any idea how many to expect from this? It was only the once. I want to get prepared as best as i can for her.
Shes a jack russel 2years of age and from a litter of 7?
Any help or guidence would be grateful.
Thank you

Answer
Hi Georgina

If she's from a big litter, there is a good chance she'll produce a big litter.  It all depends on the number of eggs she released. And as my dear Momma always says.... "it only takes one time."

Gestation is 63 days so you may want to get her a whelping box lined with old towels and sheets.  This will give her a safe place to whelp and raise her pups.

Good luck