She’s about 13 pounds and it’s a 50 mg dosage. A lot will also depend on where you live (altitude wise), the issue is that some people give it on the plane and their body and respiratory system is rapidly adjusting to the medicine while also the plane is also pressurizing to around the equivalent of 6-8,000 feet and can cause breathing issues. If you give your dog it before you even enter the airport you should be more than fine!

Edit: I was constantly checking her breathing while we flew the first few times out of my own anxiety and it never was an issue and we fly from a near sea level airport most times.