Cause
Transmission to dogs and cats occurs by several methods.  The dog or cat can eat the infective hookworm larvae, which is passed and develops within the feces of an infected animal. The worms can also penetrate through the skin, or they can be passed in the mother's milk to the nursing puppies or kittens.  In rare cases, the parasites can be transmitted through the placenta before birth.  Dogs and cats that eat an animal infected with hookworms -- such as a rodent -- may also become infested with the parasite.  Humans can fall victim to the skin penetrating abilities of hookworms and develop irritating skin lesions called cutaneous larval migrans.