Umm... no. 'Check this box if you have an allergy that needs to be accommodated" (simplifying, pick the wording however you want). If that box is checked, you get an ENTRY box: 'What are you allergic to (ex: pet dander, peanuts, legumes, cats, pollen, etc)?': And they fill out the box. That information is just displayed anywhere it needs to be.
I'm curious... if you would have been told there was going to be a cat on your flight, what would you have done? I see three options:
1) Ask that the cat not be brought on the flight.
2) Ask to change flights.
3) Deal with it.
Obviously you dealt with it, but what would your choice be (if you were given the choice)?