Surgery

CPR on a Horse–A Group Effort

By Adam Marcus

How many equine veterinarians does it take to perform CPR on a horse?

Although a minimum number might be hard to specify, a new case report in Veterinary Anaesthesia and Analgesia suggests that 4 may be enough.

The patient, an 8-year-old, 525-kg (1,157-lb) Quarter horse gelding, had undergone surgery for the removal of the right fourth metatarsal bone. The procedure itself was uneventful. However, after the animal had been hoisted into a recovery position, routine thoracic auscultation revealed an absent heartbeat, and manual palpation of the facial artery disclosed an absent pulse. These, plus other signs, indicated cardiopulmonary arrest (CPA).

“Possible causes of CPA in this horse include apnea during transport, abrupt discontinuation of dobutamine infusion, changes in body position during hoisting, or a combination of these factors,” the researchers, from the University of Adelaide, in Australia, reported.

Four people on the clinical team immediately began taking turns administering CPR, using the “knee-drop” technique to deliver between 40 and 53 compressions per minute. Each person provided 2 minutes of CPR before being relieved.

Meanwhile, the team provided positive-pressure ventilation at 4 to 6 breaths per minute, administered 2 boluses of IV epinephrine at 0.002 mg/kg of body weight, and used capnography to monitor end-tidal carbon dioxide—a marker of perfusion.

After the fifth round of CPR, the horse’s end-tidal carbon dioxide rose significantly, suggesting the animal had resumed spontaneous circulation. The team began a sixth cycle of CPR but stopped less than a half-minute into the process to listen for a heartbeat, which they found, along with a pulse at the facial artery.

The horse was then allowed to stand, and although it was in evident distress—shaking, sweating and unable to bear weight on its right thoracic limb—the animal appeared to have recovered.

Examination revealed a systolic heart murmur and an overly rapid heartbeat, both of which had resolved within 2 days of the incident, at which point the horse was able to walk on all 4 limbs.

The researchers noted that between 30% and 50% of perianesthetic deaths in horses result from cardiopulmonary arrest or cardiovascular collapse after surgery.

“Chest compressions in reported cases were performed at a lower rate (30-53 compressions/minute) than in an experimental study (80 compressions/minute) assessing the efficacy of the knee drop technique for generating blood flow. The [end-tidal carbon dioxide tension] values observed in the present case indicate the effectiveness of the knee-drop technique in adult horses,” they concluded. MeV

For more information:
Munerato MS, Simon O, Nicholson A. Return of spontaneous circulation after cardiopulmonary arrest in an adult horse recovering from anaesthesia. Vet Anaesth Analg. 2025:52(5):671-676.
https://www.sciencedirect.com/science/article/abs/pii/S1467298725000558