Dogs can shed for a variety of reasons. The most common reason is seasonal shedding, which occurs in the spring and fall when dogs lose their old fur to make way for new growth. Some dogs may also shed due to poor nutrition, underlying medical conditions, allergies, stress, or genetics. Regular grooming, such as brushing and bathing, can help control shedding, but it is important to consult with a veterinarian if you are concerned about excessive or unusual shedding in your dog.