Few things instill more terror in me than seeing a flea or tick setting up shop on my pet’s body (except, perhaps, finding them on my body). These bloodsucking parasites can spread diseases to people and pets alike, and a home infestation can be a nightmare to deal with. So even though flea and tick treatments add up to considerable expense and effort, they are necessary, and you must apply them for your pet’s entire life.There’s nothing we can say to make this process cheaper or more fun, but we did enough research to help guide you. We looked at 21 treatments and picked eight—four for dogs, four for cats. A standard caution: Always consult your vet before giving any new medications to your pet.