Can a Chihuahua impregnate a pit bull dog??

Question
I see you have been a vet tech.. have you ever heard of a little dog getting a big dog pg.. I have 8 chu's and 3 pitt bulls.. One female came into heat  I kept her seprated from the male pitt for 3 weeks.. but I didnt keep my little boys from her cause I didnt think they could do it to a big dog.. Well shelbys looking pg.. Her bellys swelling and tits getting bigger.. Her valvua is still swollen to a point.. I also have a 2lb baby girl that came in after she did and I kept her from all of the males.. I kept all the males in crates while she was in heat and her lil tits look swollen a few of them and she dont look like she gaining weight.. I did have a female pitt show the sign of being pg but never no pups.. have you ever heard of this happening.. Thanks so much for any reply...

Answer
Hi Loretta,
It's possible, but unlikely without help.  Sounds to me like she is experiencing a false pregnancy. They will even develop milk sometimes!  This will go away on its own, but sometimes they will adopt an object and make it their "baby".  Most dogs will adopt a stuffed toy, or some kind of dog toy. I saw on Animal Planet, where a dachshund adopted cordless phones around the house, and if the family tried to answer the phone, she would bite them!  LOL
Hopefully, your dog won't be that bad.  She will more than likeley get over it in time, and then again..... she just might be pregnant!  You'll know for sure at the end of 63 days!
God Bless,
Becky