Because they have extremely short snouts, some Pugs easily scratch their corneas, and can develop breathing problems. They are also prone to skin infections if the crevices in their face are not kept clean. Teeth and mouth problems are also caused by the flat faces. Pugs are prone to obesity, and can reach unhealthy weights. It is therefore important to make sure pugs get regular exercise. Pugs do mind temperature extremes, so it is important to make sure that pugs do not overheat. Pugs should not be left outside in very cold weather.