I agree with ghost, flying can be really traumatic for animals, especially those who have to go by themselves in cargo. The first time I came to BsAs was for 5 months and I left my dog with a family member. I only brought her with me when I knew I'd be staying for at least a couple of years. That being said... if you must bring your dog, you should be aware that getting into Argentina isn't the problem, it's getting out. I arrived with my big dog in 2010 and paid about US$600 but the process was pretty simple, I booked her a spot on my flight with United's PetSafe program and then had to pay for a few things with Senasa upon arrival at Ezeiza. Now in 2013, however, I am planning my trip back and have been told that you can no longer do all of the paperwork, booking the spot for your animal, etc. on your own (this is only when flying out of Argentina, btw) but must use a pet transportation company, due to some change in the policies on the Argentina side. So just a heads up, it will be a couple of hundred dollars to get your pup in, but a couple of thousand to get your pup out. Not to mention the aforementioned stress that animals undergo when traveling! Just something to think about.
P.S. You can find all of the information about the health certificates and paperwork needed to fly with pets on the Senasa (Arg) and CDC (US) websites.