^* And how sick is that? Depends on the dog, and how he’s traveling. According to research done at McGill University in the 1940s, 19 percent of dogs cannot be made sick at all. In one experiment, sixteen dogs were taken out on a lake in rough weather. Two vomited in the truck on the way to the lake. Seven vomited in the boat, and one vomited both in the truck and again in the boat. Though the boat trip rendered these dogs “dejected and obviously miserable”—though perhaps no more so than the owners of the truck and boat—a later experiment with dogs on a large swing elicited much vomiting but “little subjective evidence that the dog finds the experience unpleasant.” Dogs are used to study human motion sickness because the two species are about equally susceptible. Guinea pigs are not used because they, along with rabbits, are among the only mammals thought to be immune to motion sickness.