Hookworm is a type of cat worms that is the most difficult to notice. You cannot notice it without a fecal exam. To do this, you have to take it to the vet and ask the vet to do the test on the stools of the cats. The right time to visit the vet is immediately after you notice that the cat had contracted bloody diarrhea, poor stamina or weakness. If you are a breeder, it is wise to treat the kittens with a 3 in 1 wormer. This is to make sure that the presence of the hookworm is minimized as low as possible before they are taken to the house of the owner.