We regularly see dogs for investigation of reduced ability to exercise. If the history is suggestive of overheating and investigation rules out significant structural heart disease and also disease elsewhere in the body, we may recommend use of a cooling jacket as part of our treatment plan. These jackets feel a bit like chamois leather and are soaked in cool water prior to being placed on the dog. The dog’s coat does not become wet but heat transfer from the dog’s body causes water in the jacket to evaporate thereby cooling the dog. The cooling effect can last for several hours depending on the air temperature and humidity. If further cooling is required then the coat can be wetted again and reapplied.