So, much later, I took Lotti out of the pied a terre (p.a.t.). The blood wasn't seeping through the plaster.
Should I take it off or leave it on?
In the end I decided to try taking it off. My thought process was that if it started bleeding again, I'd put another one on. If, however, I left it on, there was a good chance that Lotti or one of the Others might try and eat it, and I couldn't see that ending well.
Eventually, I got it off.
I then sprayed the claw...and the foot....and the grass with purple spray.. Then I let Lotti have a bit of a run around.
While she did that, I did some pruning. While I was pruning, the Others escaped. The three of them went on a bit of a garden rampage. Fortunately for me, they didn't reach DH's vegetables. They found themselves in a very weedy bed and had a whale of a time.