Some airlines ban brachycephalic dogs from traveling with them, including United Airlines, Delta Airlines, and American Airlines. Airlines where brachycephalic dogs are not outright banned usually have strict restrictions regarding the travel of these dog breeds. This is because brachycephalic breeds are known to struggle with flying. This is because these breeds may struggle to cope with the stress of flight, which causes heavy panting and respiratory distress. In July 2010, statistics were released by the US Department of Transportation that showed that half of the 122 dog deaths in the last five years were brachycephalic breeds. 25 of the 122 dogs were English Bulldogs and 11 were Pugs.