Alright- my concern here is the size difference with the smaller and shorter dog thinking she is boss.. I have a strange thing to toss into the mix. Believe it or not, a mild anal gland infection will give another dog the impression of "musk" meaning arrousal when actually its not there. It doesnt even have to be an infection- just an mild impaction of the anal glands. When was the last time both ( especially the bulldog) was checked by a vet for expelling the anal glands.
These anal glands can be confusing to dogs- it can convince a young male that a female is in heat, and cause fighting amoung females.. When was this last checked?