The Zentek cool coat that has been used by the professional dog handlers and sporting dog owners since 2007., is now selling to pet owners. Beside keeping their dogs from overheating, their use of phase change materials, instead of water, also provides for better blood flow to the extremeties . A phase change material is a heat regulator. Water or ice, just shuts down the surface blood flow. Dogs, cannot sweat. Shutting down the blood flow to their surface doesn't allow the blood to cool. They first noticed that older dogs , while wearing the coat, could get up easier. Then the vets and doctors, weighed in. Their explanation is that if you regulate temperature, the heart doesn't have to beat so hard.( it speeds up, to both warm and cool the blood.) In summer heat over 100F, some owners also wet the coat. This allows the water to kick start the process, and the phase change keeps cooling, and regulating the temperature.It is the first real improvement in cooling coats . And has, and will save a lot of dogs.