Reminicent of my esperience - except the cat never goes outside except by accident. I have extensive training in immunology, but am actually a CV physiologist.
As a farm kid, I was often exposed to poison ivy; rarely, poison oak. Never a problem. While an undergrad, I sometimes picked the species for botany herbarium collections. (snark - they didn’t want to reciprocate by collecting crotalids).
Years later, I ran a biomed company. My chief tool and die maker had a Wisconsin farm (NOT a hobby farm) and raised Scotch Highland cattle. I ate 1.5/year.
One spring I was out helping him with a barn raising when a neighbor stopped by to tell him he has cattle out on the county road. Yup! He had just separated calves from mammas and the calves were bawling.
One mama took down two fences to get to the complainer. We rounded them up and restrung the fencing. He warned me - there is poison ivy on the fence lines.
I said something along the line of, “Don’r worry, I don’t react.” The next two days were an epiphany.
I could densesitize, or avoid. Now on my Florida acres, I avoid and kill the MF plants.
Highlander cattle.....There aint a fence made to hold em. I once put a 9mm right between the eyes. We were butchering that day. The steer was still at a full run five miles away when he finally dropped. A very rugged breed.