ISLAMABAD - Trendy flat-faced dogs such as bulldogs, pugs and French bulldogs are twice more likely to suffer from heat stroke than other breeds, a study shows. Scientists found extreme selective breeding for flat faces has made it almost impossible for them to cool down. Dogs do not sweat like humans and therefore rely heavily on panting to lower their body temperature. But brachycephalism — having a short and wide head — in dogs makes this process far less effective, experts have found. Just 20 minutes in a car can see them develop heat stroke, and it can be fatal to dogs. One in seven canines diagnosed with the condition dies as a direct result.