Whenever the term “choke” is used in horses it refers to an obstruction or blockage in the esophagus. This is very different than the extreme medical emergency of choking in humans, whereby an obstruction of the airway or trachea has occurred. The choking horse can still breathe — but the choking horse cannot swallow.
Choke can happen whenever a horse either eats too fast or doesn’t chew its food sufficiently and the feed or hay “plug” becomes lodged in the esophagus after swallowing. Horses that become overly hungry, or are at the bottom of the pecking order, have a tendency to “bolt” or gulp down feed as quickly as possible. As a result feeds such as pellets, dry hay cubes and grains are insufficiently chewed, and perhaps more importantly, insufficiently mixed with adequate amounts of saliva for smooth travel down the esophagus.
Horses with poor dentition are also prone to choke as they are unable to properly chew their feedstuffs. Since horses are typically fastidious eaters, rarely is an obstruction due to ingesting a foreign body. Horses are also prone to choke if they are offered feed too quickly following full recovery from sedation or anesthesia.
The presentation of a choking horse varies with the timing of its discovery. Initially a choking horse appears anxious and distressed and will show repeated attempts to swallow, often extending its neck to do so. It may appear to be retching or gagging. As the choke progresses and the horse can no longer swallow the large amounts of saliva it produces, the horse begins to drain or drool large amounts of green frothy and slimy discharge through both the mouth and nostrils. The discharge usually contains food material and is caused by the buildup of saliva and ingested food in front of whatever is causing the obstruction in the esophagus. Sometimes — not always — a lump can be seen and/or felt on the left side of the neck if the obstruction is large enough and located in the upper esophagus.
Once a choking horse is recognized it is important to contact a veterinarian immediately. Although a certain percentage of chokes may resolve themselves, the risk of unforgiving complications increases significantly as the choke progresses. Therefore veterinary attention as soon as possible is strongly advised.
Upon arrival the veterinarian will assess the nature and degree of the choke. Generally a choking horse is initially sedated to relieve anxiety and lower its head to reduce the risk of inhaling food material. Sedation also helps to relieve the spasms of the esophageal musculature that typically occur around the obstruction. Other anti-spasmolytic medications may be administered as well. A nasogastric tube is then passed through the horse’s nose as a means to identify the location and nature of the obstruction. The nasogastric tube is used as a vehicle to apply gentle pressure and to repeatedly flush warm water at the site of the obstruction, gradually softening and shifting the obstruction into the stomach. Following relief of the obstruction the veterinarian will advise appropriate medications and followup care according to each individual case. The majority of choke episodes in the horse resolves with simple treatment on farm. The attending veterinarian will address any underlying causes, often recommending dental work or feeding management.
On rare occasion further investigation and treatment of a choke may be required. This may involve more aggressive means to relieve a stubborn obstruction and an endoscopic exam to assess any esophageal damage. The main complication associated with choke is aspiration pneumonia. This occurs when saliva and food material is accidentally inhaled down the trachea and into the lungs. If pneumonia is a possibility the horse will be placed on a course of antibiotics. Another complication of choke is the formation of a stricture or narrowing of the esophagus following ulceration and scar tissue at the site of the obstruction. The scar tissue can be difficult to treat and will often be the cause of repeated episodes of choke.
While choke is not considered to be an immediately life-threatening situation in horses, early detection and timely treatment are necessary to ensure a successful resolve with minimal complications.