Question 9 / 28:
A 13 year-old, castrated male Shetland pony comes to your practice for treatment of a contaminated and infected laceration on one fetlock. After attending to the wound you administer procaine penicillin intramuscular and place him in a stall to rest. Within 1 hour your technician finds the pony down with tachypnea, labored breathing and marked tachycardia. He is rapidly losing consciousness.
What is the most likely cause of tachycardia?
