Dog fleas are some of the best known and common dog parasites. They are very small insects (1.5-3 mm long), without wings and with long hindlegs, used for jumping. They also have tube-like mouth-parts with which they pierce the victim's skin and suck its blood.
They belong to the Siphonaptera order (from the Greek words siphon=tube (the tube-like mouth parts) and aptera=wingless). They are external parasites who feed on the blood of birds and mammals.
As far as regards pets, the most common are Ctenocephalides canis, i. e. the dog flea, which can be found mainly in Europe, and Ctenocephalides felis, i.e. the cat flea, which can be found in America and is the main flea which infests dogs.
So if you ask "cat fleas and dog fleas, are they the same?" the answer is no, from a scientific point of view. But chances are, if you live in America, that the fleas on your dog are, in fact, cat fleas. Of course, any now and then, they don't dislike biting humans, too.
Only the adults suck the blood of their host. They can survive for months without food, but females need to eat blood before being able to lay eggs.
The eggs are whitish and they are not attached to their host. After they dry, they fall down, in the places where the animal sleeps or spends most of its time (on the ground, furniture or bedding) - this is an important thing to know if you try to get rid of fleas.
When the eggs hatch, white larvae appear. They don't have eyes and they have hairs on each body segment. They feed on rest of blood in the feces of the adult fleas.
The flea larvae turn into cocoons and the adult only emerges when it feels the warmth or the vibration of the host. This way, as soon as it emerges, the dog flea can feed on its host.
The cat and dog fleas can transmit other parasites (such as the dog tapeworm) and diseases to pets and humans.
If the number of fleas on a pet is reduced, the bites are not dangerous, but when the host becomes allergic to the substances in the flea saliva, it can develop flea allergy dermatitis. If small animals have a large number of fleas, they can lose a lot of blood and develop anemia.