It takes only 1 ectozoon to start out the ectozoon cycle in your home. Signs your puppy might have ectozoons embody ectozoon "dirt" (tiny black flea droppings), delicate redness, severe scratching, and skin infections. To fight fleas, raise your vet for ectozoon management that is safe for puppies. Treat all pets within the house for fleas, not simply the one which will have them.