Fever, localized pain and tiredness quite commonly occur before/after a miscarriage, this does not mean however that you should not take your dog to the vet. The most common cause of miscarriage is brucellosis (a bacterial infection) which as well as miscarriage can cause still birth, sterility and other complications. There are also other infections that could have caused the miscarriage and may require a course of antibiotics to eliminate the infection.