Sorry you're daughter is experiencing hives. My husband recently went through 12 months of itching red hives.
If you want to test if the cat is the culprit, I would recommend that you stay in a place overnight (without the cat) or for a few nights to see if the cat is the culprit. My hubbie and I have both had allergy tests done. They were not very accurate for us.
Fibromyalgia, CFS, MCS, scoliosis, herniated disks, spinal stenosis, osteoarthritis, sjorgens, sleep apnea, asthma, allergies, headaches, and reflux. On a regiment of different supplements including sleep supplements. I eat nutritiously and perform prescribed stretches twice daily.
True happiness comes not from material gain but from what we can do for each other.