A palpated mare, 4 hours later her heart rate is increased. What is the most likely cause?

A palpated mare, 4 hours later her heart rate is increased. What is the most likely cause?

• A. Heat Stress
• B. Dehydration
• C. Pain from Gas Colic
• D. Rectal Tear

Answer: (D)

Pain from a rectal tear causing peritoneal irritation is the most likely explanation for a mare that develops an increased heart rate a few hours after rectal palpation. Rectal palpation carries a risk of iatrogenic injury to the rectal wall. When a tear occurs, contents from the rectum can leak into the peritoneal cavity, triggering peritonitis and a systemic inflammatory response. The body’s response to this event often includes tachycardia as a early and prominent sign of pain and endotoxemia. While dehydration or heat stress can also raise heart rate, they would typically present with broader signs (dry mucous membranes, prolonged skin tenting for dehydration; excessive panting, sweating, or heat exposure for heat stress) and wouldn’t be directly tied to the timing after a rectal examination. Gas colic related to palpation could cause acute pain, but it would usually present as immediate colic signs rather than a delayed tachycardia hours after the procedure.

Pain from a rectal tear causing peritoneal irritation is the most likely explanation for a mare that develops an increased heart rate a few hours after rectal palpation. Rectal palpation carries a risk of iatrogenic injury to the rectal wall. When a tear occurs, contents from the rectum can leak into the peritoneal cavity, triggering peritonitis and a systemic inflammatory response. The body’s response to this event often includes tachycardia as a early and prominent sign of pain and endotoxemia.

While dehydration or heat stress can also raise heart rate, they would typically present with broader signs (dry mucous membranes, prolonged skin tenting for dehydration; excessive panting, sweating, or heat exposure for heat stress) and wouldn’t be directly tied to the timing after a rectal examination. Gas colic related to palpation could cause acute pain, but it would usually present as immediate colic signs rather than a delayed tachycardia hours after the procedure.