Equine Esophageal Obstruction and Trauma – NAVLE Study Guide

Overview and Clinical Importance

Esophageal obstruction, commonly known as choke, is the most common esophageal disease in horses and represents a frequent equine emergency. Unlike choking in humans where the airway is blocked, equine choke involves obstruction of the esophagus, meaning horses can still breathe. However, this condition requires urgent attention due to potential life-threatening complications including aspiration pneumonia, esophageal ulceration, stricture formation, and rarely, esophageal rupture.

The equine esophagus is approximately 1.2 to 1.5 meters in length and extends from the pharynx to the stomach. A key anatomical feature is the well-developed cardiac sphincter at the gastroesophageal junction, which prevents horses from vomiting. The proximal two-thirds of the equine esophagus consists of skeletal (striated) muscle, while the distal one-third is composed of smooth muscle. This distinction is clinically important for pharmacological management.

Etiology and Risk Factors

Classification of Causes

Risk Factors

• Dental disease: Poor dentition leads to inadequate mastication, allowing large, poorly chewed boluses
• Bolting feed: Rapid eating, especially in competitive feeding situations
• Dehydration: Inadequate water intake prevents proper hydration of feed material
• Post-sedation feeding: Eating while heavily sedated impairs swallowing reflex
• Breed predisposition: Friesians (megaesophagus, idiopathic muscular hypertrophy); American Miniature Horses anecdotally overrepresented
• Previous choke: Esophageal scarring from prior episodes increases recurrence risk
• Age: Geriatric horses with worn teeth; foals with congenital abnormalities

Clinical Signs

Clinical presentation varies based on duration and completeness of obstruction. Signs result from the inability to swallow saliva, water, or feed, which pools in the pharynx and exits through the nostrils.