Choking in Horses

Choke occurs when the horse's esophagus (the 'food pipe' which connects the mouth to the stomach) is blocked. For this reason, the medical term for the condition is 'Esophageal Obstruction'. The blockage is most often caused by food, with the most common causes being:

  • Unsoaked pellets or other dry food
  • Bolting
  • Large food pieces
  • Inability to chew properly

Usually the horse can still breath, but due to the blockage food and water cannot pass through the esophagus. This can lead to various problems:

  • Pain. In mild cases the horse will be in some discomfort; if the blockage is extreme it will be in pain.
  • Unable to swallow.  Due to the blockage, food or water is unable to pass past the blockage.
  • Further blockage. Despite the discomfort of the blockages, horses will often to continue to eat. The additional food is unable to pass the original blockage and consequently builds up behind the blockage, making the blockage worse. For this reason, horses with choke should be kept away from food (see 'Treatment' below for further details).
  • Lung impairment. If food/saliva/water builds up in front of the blockage, it can spill over into the trachea and enter the lungs. This can reduce the lung capacity, cause further discomfort (and coughing) and may lead to secondary lung illnesses (typically, Aspiration Pneumonia).  
  • Dehydration. Due to the inability to drink, combined with increased salivation in response to the choking, an untreated horse will over time become dehydrated.
  • Suffocation. In the case of large items stock in the esophagus, the pressure on the trachea can collapse it, reducing air flow through the trachea (in the worst case, leading to death by suffocation). For this reason, certain foods such as whole apples should not be fed to horses (see 'Prevention of Colic' below).

Fortunately, choke is often easily treated, without serious side effects, especially if the condition is quickly observed and promptly treated.

Causes

The most common cause of choke is food being insufficiently chewed before swallowing. Inadequately chewed food can become stuck in the esophagus, either because it is bulky (i.e. large pieces) or because it is too dry too pass easily (chewing not only releases the moisture in food but also mixes it with saliva) or a combination of bulk and dryness. Food may be insufficiently chewed due to physical issues with teeth (e.g. worn, missing or sharp dental ridges), problems in the jaw joint (e.g. age related joint wear which makes chewing painful) or from bolting food.  

Dry foods are more likely to result in choke, especially if the horse does not have free access to water, as they are more likely to stick to the esophagus and can then build up to create a blockage. In particular, pelleted foods are most prone to cause choke since any pellets which are insufficiently chewed may be swallowed dry and upon become stuck to the inside of the esophagus can then absorb moisture to expand and thereby cause a blockage. For the same reasons, insufficiently soaked beet root is a classic cause of choke.

A common and potentially serious cause of choke is the feeding of small whole apples to horses. On occasion, horses will swallow the apples with chewing them, where the rounded shape allows them to travel partly down the esophagus and then completely block it. More seriously, as the blockage is a single hard object (as opposed to a flexible mass when food particles build up to form a blocking mass), as the muscles in the esophagus try to push the apple down, the apple may put sufficient pressure on the neighboring trachea that the trachea is collapsed and the horse suffocates.

A less common cause of choke is ingestion of foreign objects, such as wood splinters eater by horses that crib or eating of bedding materials such as wood chips.

A horse with damage or lumps (e.g. from a tumor) in the the throat may be more likely to get choke if such problems obstruct the esophagus or its normal function. A horse which has inadequate salivation due to some other medical condition is also more likely to have choke.

Prevention of Choke

Although choke is reasonably common, it can be easily prevented by understanding the causes (see above) and taking action to avoid them. Specifically,

  • Ensure that a horse always has free access to water. Frequent drinking and increased salvia results in chewed food having a higher moisture content and consequently is less likely to stick.
  • Cut up round food and hard food. Apples and similar items (large, round and hard) should be cut into pieces, not only to avoid choke but also to avoid the more serious issue of suffocation (see above explanation). If a horse had a tendency to swallow treats whole or bolt food, other large and hard items (e.g. carrots) should be first cut into small pieces.
  • Add water to bolt foods. Horses seldom bolt natural foods (e.g. hay, grass) but may do so with high-energy foods such as grain or pelleted foods. Soaking them in water before feeding increases moisture content, making them far less likely to stick in the throat.
  • Bolt prevention. There are a number of tricks to prevent bolding (e.g. putting large stones in the grain feed bucket), which should be considered with any horse prone to bolting. See Horse Bolting for more information.

If food is soaked, care must be taken that the food is not left around in a moist condition (e.g. wetting many hours before feeding, or left over food in the feeding trough), especially during warm weather, as such food can ferment and go sour (a potential cause of colic).

An annual dental inspection (with any required treatment) will help detect and correct possible dental issues which could otherwise lead to choke.

If a horse is exhausted or recovering from sedation, it is more likely to chew its food inadequately, potentially causing choke. Normally such horses should be allowed to recover before being fed.

A dehydrated horse will have inadequate salivation, increasing the risk of choke. Such horses should be well watered before being allow to eat.

A given horse may be prone to choke on a particular type of food. For example, if a horse bolts grain or bolts pelleted food, it is more likely to choke when given these foods. If a horse has dental issues or inadequate salivation, it may be more prone to choke on dry and hard foods (e.g. dry hay made from overly mature grass). Consequently, if a horse tends to choke on a particular type of food, consider the use of an alternative.

Symptoms and Diagnosis

Most of the symptoms of choke are common to other problems, so it is not always obvious if the issue is choke or something else. Furthermore, a horse with choke may exhibit only some of the symptoms. However, if you suspect choke, potential symptoms include:

  • Disinterest in eating or drinking
  • Coughing
  • Extending the neck and head, typically in a downward direction
  • Increased salivation, drool or foam from mouth
  • General indications of distress or discomfort (pacing, increased heart rate)
  • A lump in the neck or part of the neck being distended
  • Green slime may come out of the nostrils or mouth
  • Food exiting or being blown out of the nostrils

A veterinarian may use massage of the neck to find a blockage and diagnose choke. Upon reaching an initial diagnosis, it is common to pass a stomach tube down the horse's esophagus to determine if there is a blockage (if the tube cannot reach the stomach, there is a blockage) and to determine its location. Radiography and endoscopy (putting a small camera down the throat) are sometimes also used.

Treatment

If you suspect a horse of having choke, it should not be allowed to eat or drink until the problem has been diagnosed and treated. In less severe cases of choke, horses which are allowed to eat will often do so, resulting in the blockage becoming larger and more severe; as well as increasing the risk of material entering the lungs. If the horse is placed in a box, it is advisable to ensure that there is no edible bedding (e.g. straw) in the box or to observe the horse to ensure that it does not eat or drink anything, including its bedding.

In mild to moderate cases caused by simple food blockage, the blockage will often clear on its own if the horse is left in peace in a box (no food, no water). Unfortunately, if treatment is required, the longer one waits the greater the risk of further problems. Furthermore, even if the blockage clears on its own, treatment may be advisable to avoid secondary issues with lung infection or esophagus inflammation. Therefore, the horse owner needs to balance the additional costs of a veterinarian (which may be unnecessary) against the potential risks.

The nature of the treatment will depend largely on the severity of choke and the cause. Potential treatments include:

  • Placing a tube through a nostril and into the esophagus so water can be administered to the food blockage to soften and loosen it. Between doses of water, the horse is typically allowed to lower its head and let the loosened food exit by its mouth (alternatively, such food is vacuumed out). This treatment works well when the blockage is due to a buildup of food particles (such as grain or pelleted food) which can be gradually loosened and removed.
  • Drugs which may be used include sedatives (to calm the horse and allow procedures such as tube insertion down the throat) and muscle relaxants (to reduce throat spasms and allow the blockage to pass more easily past the throat muscles).
  • Gentle massage may be combined with either of the two above methods to loosen the blockage and allow it to pass.

Care must be taken with the above that water or food particles do not enter the lungs. As such, they should be performed by a trained medical professional.

In cases where the above does not work or are unsuitable (e.g. large and hard foreign object stuck in throat), it may be necessary to use surgical tools to break up the object or to remove it whole from the throat.

If the horse has become severely dehydrated (e.g. if the condition has not been detected for a day or two, during which the horse was unable to drink), an IV may be used to increase fluid levels.

Following successful treatment of choke, the horse may subsequently develop lung problems (e.g. pneumonia) due to water, saliva or food having entered the lungs either prior to or during treatment. To prevent these secondary issues, antibiotics are often administered as a preventive measure and the horse should be observed for several days to ensure that it is not experiencing any problems.

Depending on the cause and severity of choke, there may be some damage to the esophagus, leading to infection or inflammation and subsequent scarring (which can reduce the diameter of the throat and thereby increase the possibility of choke in the future). The veterinarian may administer medication to reduce or prevent such infection or inflammation.

The horse should be fed softened and wet food for some days, until any irritation to the throat has healed. This is necessary not only for the horse's comfort but also to avoid causing further irritation or inflammation. As always, a sedated horse should not be fed until it has recovered from sedation.