Most commonly, chokes occur when horses eat concentrated feed too quickly without chewing it appropriately. The feed doesn’t get softened with saliva and forms a firm bolus that gets lodged in the esophagus. However, esophageal obstruction can also occur with hay or straw, hard treats, carrots, or nonfood objects. Anatomical problems, such as poor dentition and abnormal esophagus anatomy, can also predispose a horse to choking.
While waiting for the veterinarian, it is important that you keep your horse from eating. Hand-walking or muzzling can prevent continued feed intake. Also, do not administer oral medications. Finally, it is an old wives’ tale that you can and should resolve a choke by shoving a garden hose in your horse’s mouth— this only increases the risk of serious complications, especially aspiration pneumonia.
Upon arriving, your veterinarian will conduct a physical exam. Most choking horses are sensitive to esophageal palpation, and in minor chokes the obstruction could be visible on the left side of the horse’s neck. However, if a horse has continued to eat after choking, it can result in distension of the entire esophagus rather than apparent focal swelling. A bad choke is fairly obvious to both veterinarians and horse owners, but a mild choke could be confused with an upper respiratory tract infection or colic.
There are two main schools of thought on treating equine esophageal obstruction. The first and most common approach is to sedate the horse and pass a nasogastric tube to clear the obstruction. The veterinarian lavages (flushes) the obstruction with small volumes of water and slowly removes the accumulated feed material. It is important to do this gently to prevent esophageal rupture. With a bad choke this can take upward of an hour. The second approach is based on the theory that most chokes eventually self-cure, so veterinarians might administer repeated rounds of sedation, medications to relax the esophageal muscles, and intravenous fluids to keep the horse hydrated.
Rarely, veterinarians are unable to resolve a choke using nasogastric intubation. In those cases you might need to send your horse to a referral center for further diagnostics, such as an endoscopic examination. The veterinarian can use the endoscope—a tiny camera passed down the esophagus—to identify the type of object causing the obstruction, which is especially important if it is a solid object that will not readily dissolve with flushing, such as a foreign body or a piece of carrot. Endoscopy can also help the veterinarian diagnose any anatomical abnormalities of the esophagus.
Following resolution of the obstruction, the horse will need continued care. Most importantly, chokes predispose horses to aspiration pneumonia, which is caused by feed material going down the trachea and into the lungs. This foreign material in the lungs can cause the horse to develop a secondary bacterial infection. To prevent this, many veterinarians place horses post-choke on antibiotics. It is important to monitor the horse’s temperature for several days following a choking episode, because a fever might be one of the first signs of pneumonia. Other signs include coughing, nasal discharge, and increased respiratory rate or effort. Your veterinarian might also administer sucralfate, a medication to help treat ulceration of the esophagus, or a non-steroidal anti- inflammatory drug (NSAID) such as flunixin meglumine (Banamine). Check the horse’s temperature before administering NSAIDs, as they will mask a fever.
Depending on the severity of the choke, you might need to withhold certain feed types for several days. Typically, avoid dry feeds and hays and offer the horse a soupy mash of complete concentrate feed. Repeat chokers on certain types of feed might need to remain on soupy mashes indefinitely, and horses that eat too quickly sometimes benefit from having large, smooth rocks placed in their feed tubs. Finally, a common cause of choke is poor dentition leading to inadequate chewing; be sure to schedule a thorough dental exam following a choking episode.
Chokes are common equine emergencies with potentially serious consequences. Call your veterinarian as soon as you notice signs of choke.