Dogs and cats shed hair year round, although they typically shed more as the hair coat thickens or thins during the fall and spring. The level of shedding is more of a response to the length of daylight than to the temperature. Shedding can also be affected by nutrition, hormones, and stress. Poodles shed very little and certain terriers shed less than other breeds, so these dogs need periodic coat trimming and more grooming than short-haired breeds such as pugs or beagles.
Shedding is much more noticeable in dogs and cats with long, thick hair than in those with short hair. Unless pets with long, thick coats are groomed regularly, their hair can form mats. Mats frequently develop around the ears and on the long hair on the legs, but they can form anywhere on the body. Matted hair can lead to skin conditions such as hot spots. Mats are best removed with electric trimmers; using scissors can accidentally cut the skin.