Help my dog always smells doggy?

can anyone help no matter how many times i wash my dog she smells that wet doggy smell. I have to be very carefull what i wash her in as she comes out in spots all over as she has very sensitive skin ,im useing malaseb shampoo from the vets at the moment and i gets rid of the doggy smell for a day or two then we have to bath her again she is a french mastiff so in winter its harder as i have to have help lifting her into the bath but while its nice i can do her outside