How long and often are female dogs in heat?
Many believe it's instinctual behavior, harkening back to the days when your dog's wild ancestors would mask their scent to help them sneak up on their prey.
Wolves, for example, have been observed rolling in animal carcasses or the droppings of plant-eating animals, to cover up their own smell during the hunt.
At a minimum, it's advised to bathe your dog at least once every three months.
You can wash your dog as frequently as every other week (with gentle shampoo, it could be even more frequent).
When in doubt, use your judgment — if your dog starts to smell, it's probably time for a bath.