Another study:
A 10 year old Morgan gelding had hives for the previous two to three months. He showed some response to corticosteroids and antihistamines, but the hives return in full force off medications. We stopped medications for a week and then started spirulina 20 grams twice a day. Hives were gone in 3 days.
There are more if anyone wants me to post them.
Thanks for the information. I am going to try it. I have a lot of respect for herbal medications, especially after having the Arab mare with the tumor. My vet gave us a Chinese herbal medicine and cimedidine to try and it worked wonderfully. One of our mares has skin problems, like hives sort of, that is being controlled with medicated shampoo so I will try it on her also.