Collar technologies for the prolonged topical control of ectoparasites on companion animals are reviewed, beginning with the first vinyl collars to the most recent developments. Matrix collars, such as the vinyl collar, have been the most commonly used technology, in which the active agent is blended directly into the polymer itself. Reservoir technologies, in which an active agent is dispersed or dissolved in a vehicle which is, in turn, held in a solid or mesh-like casing, are also discussed. Mechanical systems are presented including ultrasonic devices which emit sound waves designed to disrupt the flea life cycle, pumps which topically deliver small quantities of a dissolved active agent, and chambered devices designed to physically entrap the flea inside the collar. The future directions for topical parasite control are considered in closing, reviewing in particular the advent of more potent compounds.