I flew with Marcus a few weeks ago and was nervous due to his tiny size about traveling too. He did great and it was def harder on me than him. I brought a full tube of Nutri-cal with me in my carry on. When we went through security, they pulled the Nutri-cal out to check it. It was also larger than the amount allowed. I told them that it was medication he needed to ensure that he did not go into a hypoglycemic fit (which is the truth when dealing with these little guys). Since it was medication, they allowed it. The second leg of our returning flight was delayed so we were stuck in the airport for eight hours. Marcus isn't wee pad trained and refuses to have an accident in public. So we had to go all the way out of the airport to find a grassy area close by. Due to the long delay, we had to repeat this three times, each time having to go all the way back through security and be checked out again. We had different security people each time and all said the Nutri-cal was ok since it was a type of medication. Hope this helps and you and you furbaby have a nice trip!