There is no single right answer to how often a dog should be bathed, and Hosur makes the question harder. Dust from the roads, long hot afternoons and the humidity before the monsoon all leave a coat dirtier, faster. But bathing too often strips the natural oils that keep skin healthy, so more is not always better.
As a rough guide, a short-coated Indie dog that mostly stays indoors is comfortable with a bath every three to four weeks. A long-coated breed like a Shih Tzu or a Lhasa needs more frequent, careful washing because dirt and matting build up close to the skin where you cannot see it.
Watch the dog rather than the calendar. A coat that smells, feels greasy or looks dull is asking for a wash. Flaky skin, constant scratching or a dull coat just after a bath usually means you are washing too often, or using the wrong shampoo for that coat.
Whatever the schedule, the shampoo matters more than most owners think. A coat-appropriate shampoo, a proper rinse and a full dry — right down to the undercoat — prevent far more skin problems than any single bath ever causes. If your dog's skin looks irritated, stop guessing and ask a vet before it turns into an infection.