Although there are species named dog fleas ("Ctenocephalides canis" Curtis, 1826) and cat fleas ("Ctenocephalides felis"), fleas are not strictly species-specific. A study in Virginia examined fleas collected from 29 dogs. In total, 244 fleas were identified and all turned out to be cat fleas. In fact, dog fleas haven't been found in Virginia in more than 70 years, so it is very likely that a flea found on a dog is actually a cat flea ("Ctenocephalides felis"). In fact, dog fleas may not even occur in the US.