Poor girl wasn't feeling so hot the day after her vaccines & had developed some edema on the side of her neck where she got the 5-way. She wasn't the only one; sounds like almost 10% of the horses had a reaction! some much worse, so the vet was called. All the horses were vaccinated with the same lot so it seems that it's just an individual reaction. He recommended cold water & Bute.
I saddled her up & we took a walk out in the desert since it can't hurt to pump some blood around. Beautiful, calm, 80 degrees. Afterwards I hosed her neck with cold water which she actually seemed to enjoy - it was a little tender where the swelling is so the cold must have felt good. She was pretty mellow yesterday.
Hopefully today she'll have some energy back & the swelling will be down.