While you might adore your Himalayan's pushed-in nose, that facial configuration can cause all sorts of breathing problems during air travel. Many airlines won't allow Himmies, their Persian cousins and other brachycephalic cat and dog breeds on board. Those policies result from the fact that the well being of these animals are at higher risk during flights.
Brachycephalic means "short head." That's a pretty good description of your Himmie, as well as dogs like the Pekingese or Shih-Tzu. The pushed-in face typical of these breeds results from a short skull, with shorter bones in the nose. Breathing difficulties associated with the head shape usually worsen over time.
Brachycephalic Airway Syndrome
Brachycephalic airway syndrome occurs in affected canine and feline breeds because of their possible elongated soft palates -- which partially block their windpipes -- and small nostrils. Affected cats must work harder to breathe. Symptoms include noisy breathing, snoring, collapse after mild exercise and coughing, all of which get worse in humid and hot weather. They also get worse when the air is thin, as in air travel, when much more effort goes into breathing for an already stressed feline.
Atlantic Airline's website puts it bluntly: "Himalayan and Persian cats should not be transported by air as these breeds are more susceptible to breathing difficulties caused by the thin air at altitude." Other airlines share this sentiment, but some will allow you to take your Himmie aboard if you sign an acknowledgement releasing them from liability if your short-nosed pet suffers from respiratory problems during travel. Your best bet might be arranging alternative ground transportation for your cat or pay for him to fly on a private plane catering to such pets and their needs.
It's possible to have your cat's nostrils surgically widened, which might help alleviate breathing difficulties and allow him to eventually travel safely on an airplane. Since this is a special procedure, ask your vet to recommend a surgeon who regularly performs these operations. Widening the nostrils includes removing a tissue wedge from the inside of each nostril. Because a cat's nostrils are so small, traditional scalpel surgery is generally safer and offers better results than laser surgery, according to Michigan-based Vet Surgery Central. It's also possible for your cat's elongated soft palate to be surgically shortened, allowing better airway function.