Prior to the publication of A comparison of jump performances of the dog flea, Ctenocephalides canis (Curtis, 1826) and the cat flea, Ctenocephalides felis felis (Bouché, 1835) (M.-C. Cadiergues, C. Joubert, M. Franc; 2000), most performance measurements for fleas were performed with the oriental rat flea (Xenopsylla cheopis), which is well-known for being the primary vector for the bubonic plague. The authors don't explain why they conducted this research, but the fact that their lab had been maintaining a colony of cat fleas on cats and dog fleas on dogs for years makes the decision sound like it came on a particularly boring Saturday morning, after a night of heavy drinking.
They put together an experimental setup for horizontal jump measurements: sticky plastic, and for vertical jump measurements: vertical cylindric tubes of varying height. They measured the horizontally leaped distances for nine hundred different fleas, and the vertically leaped distances for one thousand and five hundred; and presumably stayed sane until the end of the process. Standardly, fleas walk while on a host - they only engage in jumping when they get disturbed, or if the host's temperature decreases.
The dog fleas' jumps were significantly longer and higher than the cat fleas', which makes perfect sense.