3:30 pm Update: Bloodwork just came back showing a significant amount of venom in his bloodstream. The vet has located some anti-venom locally and sent for it. I didn't realize that since the anti-venom is so expensive, most clinics do not keep it on hand. The vet is worried since Mickey only weights 8 pounds.
7:30 pm Update: His blood pressure dropped this afternoon, but once the anti-venom drip started, he seemed to improve a bit. The vet wanted him transferred to our local Emergency Vet Clinic tonight so he could be monitored closely, so we picked him up and took him there. I was pleased because he can hold his head up, which he couldn't do this morning. His front leg is swollen to triple its normal size. In the morning, we'll take him back to his regular vet for the day. Hopefully, he'll have a good night.