Due to a simple puncture that turned nasty. In a matter of overnight, her foot swelled like crazy all the way to the hock joint. I take her to vet first thing in the morning and he says wow. He keeps her, probes and cleans just like any other time and puts her on Baytril. In addition, I soak her foot twice a day and flush with Prepodyne. The swelling went down and A LOT of puss drained but the last part stayed swollen and pussy. I take her back in and dropped her off. The vet was sure he got all foreign matter. I come back later in day and he had to slice in along the tendon where this nasty infection was hiding and he had to scrape it out (no foreign matter) but a nasty, gooey area. Poor girl's foot is tender and I have to take her in every two days for follow-up until we get this fixed. Just WOW! I don't know what the heck bacteria this was and I hope to never see it again.