my chihauhau had two miscariages

Question
hi my name is johnathan and i have a 4 year old Chihuahua And she had two miscarriages when first got her i mated her wit a jackrussle she had the puppies with no problem.
like 9/10 months later she came in heat again and i mated her with a larger dog that i thought was a jack but it wasn't it was some type of terrier and she had a miscarriage she had 25 more days to go before her due date but then she had the miscarriage the pups were very large and i thought that would be why she had a miscarriage could that be the reason? then the second time she did the same thing she was pregnant by the same dog and the same thing happen and the pups were still large. but now she is pregnant by a small Chihuahua and she is doing well do U think that it could be that the pups grew to big in side her?

Answer
Hi. It is really hard to say for sure why your girl had two miscarriages. It could have been because of the pups' size, it could have also been because of an infection, disease, anything. Miscarriages in dogs are rare. If you breed a dog on each heat cycle (I don't know if that's what you did or not), it can cause serious problems with the dog, including miscarriage. I would have an x-ray done after day 50 to check on the size of the pups. Good luck!