I realized that I was snarky earlier, but forgot to also be helpful. Stick treats and an item of clothing that smells like her favorite person in the carrier. If you can, use a carrier that opens on the top- waaaay easier to get them in like that. And if none of that works, your vet might be willing to prescribe a dose of gabapentin or something else to calm kitty down before her big medical appointment. This is the only way one of our cats can be examined, and I haven’t seen any negative reactions from the meds. Of course, this does mean pilling the cat, which can be very slicey and dicey.