Are rats dirtier than dogs?

Comparing whether rats are dirtier than dogs depends on whether you mean wild rats or pet rats, and what aspect of cleanliness you mean. Wild Norway rats and roof rats live in sewers, garbage areas, attics, and walls, come into contact with droppings, urine, and decaying material, and can carry pathogens like salmonella, leptospirosis, and parasites like fleas, so in terms of disease risk and contamination of food and surfaces, wild rats are considered much dirtier than pet dogs that are bathed, vaccinated, and live in clean homes. Wild rats constantly urinate to mark territory and produce many droppings that contaminate homes. Pet dogs, while they can track in dirt, shed hair, and carry some bacteria in their mouths, are generally cleaner in a household sense because they are groomed and their waste is picked up. Pet fancy rats that are kept as companions are actually very clean animals, they groom themselves constantly like cats, spend hours cleaning their fur, and can be litter trained, so a pet rat in a clean cage may be cleaner than a dog that rolls in mud. So wild rats are definitely dirtier than dogs, but domesticated pet rats can be quite clean, sometimes even cleaner than dogs in terms of personal grooming habits, though both need regular care.