Horses and Hiccups

Hiccups in horses occur when the animal's diaphragm and flank area contracts forcefully with each heartbeat, thereby producing a thumping sound in its chest. For this reason, horse hiccups are referred to as equine "thumps" or, scientifically, synchronous diaphragmatic flutter (SDF) or singultus. Although equine thumps themselves are not a problem, they're typically associated with a more serious underlying issue that should be treated.

  1. Causes

    • Low blood calcium levels are the classic abnormality associated with equine thumps, however hiccups also are caused by dehydration and abnormal electrolyte levels brought on by athletic stress. Thumps may result when horses are given the diuretic drug Lasix, since it alters normal blood chemistry levels. Other causes include overeating, colic, elevated blood pH levels, or a hormonal imbalance in mares. Regardless of the root cause, the result is that the animal's phrenic nerve becomes increasingly irritated, which stimulates the electrical activity of the heart and causes the diaphragm to become highly sensitive and contract.

    Athletic Connection

    • Thumps are generally seen in racehorses and endurance horses because their intense workouts result in significant sweating, which leads to dehydration, low electrolyte levels and high blood pH levels. According to Dr. Cristobal Navas de Solis of the University of Illinois College of Agriculture, "...thumps is common in Arabian horses competing in long distance races that last 25, 50, or even 100 miles." He points out that although these horses present lower-than-normal blood calcium levels, the condition disappears naturally once the underlying issue of dehydration is treated.

    Complications

    • Equine thumps can be a recurring problem in horses exposed to continual exertion and stress, and therefore puts them at risk for serious phrenic nerve injury. Because horses that hiccup don't appear to be sick or distressed, most owners believe that there's nothing physically wrong with them. According to Mike Foss of Pacific Northwest Endurance Inc., research indicates that horses that suffer from recurring thumps endure considerable cellular damage as a result of low calcium levels and the corresponding reactions of free radicals in their system.

    Treatment

    • Treatment for thumps should begin with electrolyte analysis via blood samples to ensure proper administration of treatment options, depending on the underlying cause. For horses suffering from colic, dehydration, or overexertion from training or exercise, providing a calcium supplement that contains electrolytes should offer relief. However, more serious or complicated issues may require treatment with intravenous fluids, which contain calcium, to restore proper electrolyte and calcium levels.

    Prevention

    • Offering horses alfalfa hay, which is high in calcium, and maintaining proper hydration is essential to preventing thumps. When riding a horse in hot weather or exposing a horse to rigorous training or exercise, it's imperative to provide an ample supply of fresh, clean water at regular intervals to prevent dehydration and maintain proper blood pH and electrolyte levels. Adding electrolytes to the water may also help in the prevention of hiccups.