All Choked Up

Equine Esophageal Obstructions

By Garrett Metcalf, DVM

Horses that experience an esophageal obstruction can be a quite frightening and confusing situation at times for horse owners, especially if it is witnessed when it occurs. Horses do not technically choke per se in comparison to human choke that causes airway obstruction, but rather have a bolus of feed or other objects become lodged in the esophagus at various levels. In other words, standard emergency procedures in humans like the Heimlich maneuver will not correct an esophageal obstruction, but there are several techniques to correct these obstructions in horses.  Additionally, there can be complications that can develop secondary to the choke that may put the horses’ life in danger.

Anatomy

The equine stomach is composed of several layers of tissue that are rather elastic to accommodate feed material to pass from the pharynx to the stomach which is no short trip at about four to five feet in length. There are two muscles that make up the esophagus with the proximal 2/3 striated muscle and the last 1/3 smooth muscle. The esophagus passes down the left side of neck, dips down to pass into the chest, back up over the heart, through the diaphragm and into the stomach.  There are several areas that obstructions occur where the esophagus changes direction and also passes through more narrow regions like at the entrance of the chest and the diaphragm. The beginning of the esophagus is directly above the opening of the trachea, putting the airway at risk of feed material or contents entering it during a choke episode.

Causes and Predisposing Factors

Choke is the most common disorder that affects the esophagus in horses. Besides the obvious cause of choke from large bulky material that is not able to pass down the esophagus, there are occasionally other causes of choke. Treats, apples, hay, grain, foreign material such as wire, rope or other objects have been culprits of causing choke in horses. Injuries to the esophagus such as direct blows to the neck or lacerations can cause scarring or restrictions of the esophagus, putting the horse at risk of choking.  Other predisposing factors are poor dentition or bad teeth, which often comes with age. Dental conditions such as poor dental occlusion from a wave or missing teeth can predispose to choke. Older horses with dental issues often cannot properly grind hay or grain to appropriate size to be swallowed, necessitating special diets that will reduce the risk of choke. Dehydrated hay pellets or cubed hay can be a risk factor of choke if not rehydrated before feeding to horses.  It’s not uncommon to have young horses choke due to competition with other horses for their meals or gluttony like behavior over feed.

Clinical Signs

Horses that are experiencing esophageal obstruction can have various clinical signs, but there are hallmark ones that are rarely mistaken for other conditions. The number one thing is feed material and fluid/saliva coming out both nostrils. Sometimes the onset of choke is witnessed by owners, making it rather easy to diagnose the problem. Depending on the temperament, age and whether the horse has experienced choke before, horses can display signs of panic like behavior of thrashing, rolling and pawing that mimics signs of colic. Often horses will cough because of the close anatomical location of the esophagus to the trachea, leading to some amounts of feed material or saliva entering the wind pipe. Horses will attempt to swallow multiple times or even display a gag like reflex or retching motion by flexing and stiffening of the neck briefly. Occasionally a bolus of feed can be seen in the neck but often the obstructions occur at the base of the neck or further down the esophagus where it cannot be visualized.

Read more in the November issue of Oklahoma Farm & Ranch.