I can only offer what I would do with Boo...I don't know if IAA cats act differently than acro. I did look at her ss and she's shot this number before.
If this had occured at night or on a weekend, I would shoot the full dose and monitor it to collect data.
Can Jan run home at lunch? If so, I might shoot the full dose and feed him HC for breakfast and then run home to check at lunch.
If she can't run home at lunch, I would BCS the dose...maybe 5 u? And again, leave HC to make her feel better.