So a 74xx244 works at a commercial operating temperature, while a 54xx244 which is the same logic device [maybe the same pinout, and package] will continue to operate to the military operating temperature range [which is wider].
A distemper vaccine is more than a preventive against canine distemper virus. This vaccine, considered a core vaccine for all dogs in the United States, also protects against a host of other diseases you may not know your dog is susceptible to. These can include adenovirus, parvovirus, and others.
Distemper and parvo viruses are deadly and can be spread via airborne or direct contact of bodily fluids. Distemper/parvo is not a vaccine required by law, however it is considered a core vaccine (a vaccine that should be given to all animals of a certain species).