This article is from the March 2020 Horse Deals magazine.

In humans choke is the obstruction of the trachea (windpipe), whereas in horses it is a blockage of the oesophagus (food pipe), usually with food material. So unlike choking in people, choke in horses doesn’t interfere with the ability to breathe, and therefore does not pose an immediate threat to life. In fact, some cases can be mild and will quickly and spontaneously resolve on their own. If a choke doesn’t quickly resolve however, the consequences can be serious. A choking horse unable to clear the obstruction is an emergency and will require immediate veterinary intervention. A horse with choke is unable to swallow, cannot eat or drink and may become severely dehydrated. Aspiration pneumonia (a very serious lung infection) may also develop as a complication if food material and saliva accumulate and are aspirated into the trachea and down into the lungs. Damage to the oesophagus can also occur causing pain, inflammation and infection. This may result in strictures of the oesophagus forming and an increased likelihood of future episodes of choke. In the worst cases, if the oesophagus ruptures then shock and infection can result in death.

Causes of choke

A common scenario is with greedy horses that “bolt” their feed, meaning that they eat too fast. These horses are at risk of choke as they try to swallow down as much feed as quickly as possible. Older horses and those with poor dentition and the inability to properly chew their food are also at risk. Certain types of feed can also predispose a horse to choke. Compressed pellets in feeds tend to be very dry and can then expand when exposed to moisture causing a blockage. Apples, carrots or other treats can also cause choke if the horse swallows them without properly chewing them. Tough, fibrous plants eaten in the paddock or eating hay may also occasionally lead to choke. Horses may also choke on foreign objects such as pieces of wood.

Clinical signs

- The horse may appear to have difficulty swallowing or no interest in feed
- The horse may appear ‘anxious’ and neck muscles may look very tense
- There is often gagging, coughing and retching
- The horse may extend the neck and head downwards or shake his head
- There may be discharge from the nostrils, usually green in colour (but could be brownish or clear) and this may also contain feed particles or grass
- There can be saliva drooling from the mouth
- On physical exam your horse may have an elevated heart rate due to stress and panic
- Occasionally, a lump on the left side of the neck is visible or can be felt.

What to do

If you suspect your horse is choking immediately remove access to all hay, feed and water, and do not let the horse graze. Some choking horses may attempt to continue eating, which will only increase the size of the blockage, making it worse. Any choke that continues more than a few minutes is an emergency that requires immediate veterinary attention so call your vet and try to keep your horse calm while you wait. Do not try to squirt water or put the hose into your horse’s mouth. You will greatly increase the risk that he will develop aspiration pneumonia if he inhales any of the liquid into his lungs. Do not administer medications or home remedies or rub the horse’s neck at the site of the blockage. None of these things will help and you may make the situation much worse if you inadvertently cause injury to the lining of the oesophagus.

Treatment

Your veterinarian will usually administer sedatives or muscle relaxants to make your horse more comfortable and relax the contractions of the oesophagus. In some cases, this may be enough to allow the obstruction to pass on down into the stomach where it can be digested. At this stage your vet will likely pass a stomach tube via a nostril down into the oesophagus. This is to either confirm that the blockage has cleared or that something is indeed blocking the oesophagus, and how solid and how far down the oesophagus that blockage is. Sometimes the insertion of a stomach tube is enough to gently push the obstruction down into the stomach clearing the choke. If not, the horse is heavily sedated so his head hangs low to the ground, and the obstruction is flushed with water via the stomach tube. Water is poured into a funnel attached to the stomach tube and allowed to run back out of the nostrils. This works to gradually soften the blockage and flush some of the obstructing material out. This can be a long process and patience is needed to avoid causing damage to the oesophagus. Having the horse’s head hanging low and keeping him relaxed with sedatives helps to minimise the chances of water being aspirated into the lungs. In some cases, this may need to be done under a general anaesthetic with a breathing (endotracheal) tube in place to protect the airway.

An endoscope may be used to visually assess the blockage or to check the lining of the oesophagus for damage after the choke has been cleared. Additional imaging such as radiographs (x-ray) or ultrasound may be used depending on the individual case.

Surgery is usually not necessary but may be performed as a treatment of last resort to manually remove the blockage. Surgery can result in complications; especially regarding healing of the oesophagus, so most vets will avoid it if possible.

After care

When the obstruction is cleared, your veterinarian will decide whether they need to administer a course of broad-spectrum antibiotics to prevent infection of the lungs. It is important to give this medication as directed and complete the course of medication provided, even if you initially think your horse seems fine. Your horse will also usually be prescribed a course of anti-inflammatories for any discomfort and to reduce inflammation of the oesophagus that could progress to form strictures. Strictures are areas of narrowing caused by scar tissue which could predispose him to episodes of choke in the future.

It is also likely, depending on the severity of the choke, that you’ll be asked to avoid any feed for up to a 12 hour period followed by a few days of small, soft, wet feeds to give the swollen oesophagus some time to heal.

If following an episode of choke your horse seems dull, depressed, goes off his feed, has an elevated temperature, an elevated respiratory rate, nasal discharge or coughing, call your vet immediately to let them know, as further treatment or tests may be required.

Prevention

The most important management considerations are:
- To soak dried foodstuffs to allow them to swell before they are eaten and swallowed.
- Discourage the bolting of food: you can place large, flat stones in the feed bucket so he has to eat around them (large enough so that the horse cannot swallow them) or feed smaller meals more often or use feeding toys or specially designed slow feeding buckets to slow him down. If your horse eats quickly because he is worried his paddock mates will steal his food, separate him from the herd at feed time and feed him by himself.
- Schedule annual or biannual checks from your equine dental veterinarian. Regular dental care to assess for any pathology and to float any sharp enamel points off the teeth ensure your horse is comfortable, and allow him to chew food thoroughly and effectively before it is swallowed.
- Provide permanent access to clean, fresh water to encourage the horse to drink normally.
- Some horses will choke on a particular type of feed or treat and you should in future avoid feeding this.
- Cut apples, carrots, or other treats into small pieces.
- Withhold feed material for at least one hour following sedation.

Article written by with Dr. Rachel O’Higgins BVMS MRCVS from Kilmore Equine Clinic

Sign up to our newsletter