Lemon juice does not kill fleas on dogs, but it does deter them. Making a homemade solution of water and lemon juice helps get rid of fleas on pets and in homes.
Making a lemon spray that deters fleas requires six lemons cut in half and a quart of water. Boil the lemons in the water for 5 minutes. Turn off the heat, and cover the pan. Let the lemons steep overnight. In the morning, pour the solution into a spray bottle, and lightly spray the animal's coat, being careful to avoid getting the solution in the pet's eyes. Spray the pet's bedding too.