Choking in horses is different than humans as it is an obstruction of the esophagus rather than the trachea. Despite this difference, it is still an emergency in equines. The cause that comes to mind most commonly is food acting as a foreign body but there are a multitude of reasons for a horse to choke. Intraluminal causes are things such as food or a foreign body that blocks the opening of the esophagus. Whole apples that aren’t chewed properly are a prime example. Intramural causes are diseases that affect the wall of the esophagus. If the horse has a mass or abscess that increases the size of the esophageal wall, this decreases the size of the lumen making a smaller passageway for feed material. Extramural are diseases that affect structures close to the esophagus. Again, any sort of mass that grows and pushes the esophageal wall inwards will narrow the opening. The final category is functional. This includes anything that decreases the body’s ability to swallow and pass food down the tube. Dehydration or decreased saliva production makes the passage of food more difficult and increases the likelihood of food getting stuck. Any drug or disease that interferes with the innervation or coordination of the muscles will disrupt the flow of food down to the stomach. Sedatives decrease the horse’s ability to swallow.
When a horse is choking you will often see signs of panic or anxiety. Commonly they will have their head and neck extended out and be gagging or retching. You can also see coughing and/or nasal discharge. Sometimes this nasal discharge will be food, other times it may simply be mucous. Continual swallowing and hypersalivation can be seen as the horse attempts to pass the feed down to the stomach. If there is a large obstruction, it can sometimes be seen along the jugular groove.
Once you have determined your horse is choking you should call the veterinarian immediately. When I arrive on farm or the horse arrives at the clinic, I like to give 3 separate drugs. The first is sedation. My goal is to sedate the horse to the point where the nose is to the ground. This will allow any fluid or feed material to drain out of through the nostrils, rather than down into the lungs. The second drug is banamine (also known as fluinixin). This is an anti-inflammatory and pain medication. This will help reduce the inflammation of the esophagus, which will in turn help allow for the blockage to be resolved and aid in preventing complications from the choke. The third is buscopan. This drug acts to relax smooth muscle. Naturally, the body is attempting to constrict the esophagus to help push the blockage along the gastrointestinal tract. This makes passing a nasogastric tube more difficult and increases the risk of complications. Relaxing the smooth muscle around the obstructions makes pushing it to the stomach easier. Once the drugs have taken effect, a nasogastric tube is placed. Gentle attempts to dislodge the obstruction are made. If the obstruction does not resolve, lavage can be performed to try to break up the food material if possible. In very difficult chokes, endoscopy may be used to visualize the obstruction as well as to assess the esophageal lining and look for causes of the choke.
Complications with choke are a major concern. The longer a horse is choked, the higher the chance for complications. The esophagus is a delicate structure and any damage is severe. If there is any damage, the body will heal it with scar tissue. This tissue is not elastic and will form a stricture, or a narrowing of the esophagus. This predisposes the horse to choke in the future. If a choke is left long enough, there is decreased blood flow to the esophagus around the obstruction and the tissue can develop necrosis and the esophagus can rupture. Not only is the esophagus at risk of complications, but the airway too. The horse is unable to protect the airway and food material can descend through the trachea into the lungs leading to pneumonia. For this reason I strongly encourage all owners to monitor the temperature of the horse to look for signs of infection. Antibiotics are also often given to protect the lungs from infection.
After care is important to try to prevent another episode of choke. Soaking hay cubes allows the horse to get lots of water as well as allows an easier passage into the stomach while the esophagus heals. A slow transition can be made to get the horse back on regular feed. Once a horse has choked, they are at a higher risk of choking in the future. At the Dawson Creek Veterinary Clinic, we want to ensure your horse is happy an healthy. If you have any questions or are concerned your horse is choking, please contact the clinic immediately.