The flea on the dog is a blood-sucking ectoparasite. There are two main harms to the dog. The above fleas can spread infectious diseases and parasitic diseases. Second, fleas have strong irritating effects on the skin, causing severe itching. Feeling, the dog is forced to scratch, it will cause skin damage, and harassing the dog can not rest well, causing loss of appetite and weight loss. In general, the onset of dogs is characterized by scratching, rubbing and biting the coat. In severe cases, it causes hair loss, hair loss and abrasion. In severe skin wear, there is liquid exudation and even formation of purulent wounds. Sometimes it can cause allergic reactions and form eczema.