The USA is one of the most common destinations to fly dogs and cats to in the world. Lots and lots of flights fly from Ireland to the USA every day and this makes it much simpler to transport your pets. The longest direct flight is 11 hours to Los Angeles. On a long haul flight like this pets are much more competent than humans and settle down very quickly and don’t even realise they are flying after a short time in the air.
Ireland is still classed as rabies free by the USA government and the rules for importation of dogs and cats are governed by the Centre for Disease Control. From a veterinary point of view, it is very simple to import a dog or cat from Ireland to the USA. The only thing you really need to do is get a quick checkup for your pet to ensure they are fit and healthy enough to fly.
You should definately have your dog or cat vaccinated against rabies at least 30 days before they enter the USA and have a microchip to identify them. If a dog or cat is imported into USA and does not have a rabies vaccination, then the owner has to sign a confinement agreement, which states that they need to be kept away from other animals until a period of at least 30 days after a rabies vaccination. Different states impose this rule differently. For example, Florida insist that imported dogs and cats do have a valid rabies vaccination, but the rest of the USA seems to be a little more lax on this rule.