Knowing when to change the bedding in a hamster cage is crucial for the pet's health and hygiene. The bedding should be changed when it smells or if a significant portion becomes soiled. Daily spot checks are essential; look for damp spots, especially under the water bottle, and areas with droppings. Hamsters also tend to stash food, so it's vital to check for hidden food that may be rotting. Regular bedding changes, ideally once a week or more frequently if needed, ensure a clean and healthy environment for the hamster.