Text: Hannah Botha, MSc Equine Science
As owners and loving carers of our steeds, it’s always nice to see our horse rushing to his feed bucket and finishing every bit of food in sight. Commonly, this is believed to be a sign that the horse enjoys his food. However, in some cases, the speed at which a horse eats their food could put them at risk for choke, otherwise known as oesophageal obstruction. Choke can be caused by food or foreign matter.
Not immediately life-threatening
Unlike in humans, choke in horses is not an immediately life-threatening condition. In humans who choke the trachea (windpipe) is blocked preventing the individual from breathing. However, in horses with choke it is the oesophagus (the muscular tube leading from the mouth to the stomach) that is blocked. Therefore, the airflow to the lungs is not compromised in choking horses in the same way that it is in choking humans.
Mechanism
Choke occurs when food or a foreign object gets stuck in the muscular oesophagus of the horse. The muscular oesophagus normally contracts to force food down into the stomach of the horse. However, when food or a foreign object gets stuck, the muscles that line the tube may contract and spasm around the blockage, preventing the obstruction from moving down into the stomach. This situation needs resolving as soon as possible. Once the food or obstruction arrives in the stomach, which has a much larger diameter, it is unlikely to cause further problems as it passes through the rest of the digestive tract.
Why does choke happen?
The most common cause of choke is swallowing too much too quickly or “bolting” food. The other common cause is swallowing anything that has not been thoroughly chewed and moistened with saliva, which occurs more often in older/younger horses that perhaps don’t have good dentition. A rarer cause is partial obstruction of the oesophagus due to scarring from an old injury or a tumour.
Signs of choke
Horses usually show signs of choke pretty quickly after the blockage occurs. Some of the common signs of choke include:
- extending the neck
- moving away from the feed bucket
- looking worried or anxious
- standing with head down and legs spread wider than normal
- coughing
- snorting
- gagging or unusual noises
- saliva dripping from the horse’s mouth and nostrils. This may appear as a greenish or brownish discharge, often containing particles of feed substance.
- other signs of distress such as pawing, sweating and box-walking are also common.
Is choke a serious problem?
Horses, unlike humans, can’t breathe through their mouths, and thus a blockage would only inhibit further swallowing, rather than putting them in danger of suffocation. However, the situation can still become serious if the obstruction is not removed quickly.
“Possibly the most serious complication occurs when saliva backs up behind the obstruction and then is pushed into the trachea or windpipe. Normally, the horse’s head-down eating position keeps this from occurring, but when the oesophagus is blocked, saliva and food particles may be forced past the epiglottis, a flap of cartilage that keeps swallowed food and water out of the trachea. In a horse with choke, some of the saliva drains harmlessly from the nostrils, but saliva and grain particles may also be drawn into the lungs, and pneumonia is the common result” (KER 2008). Pneumonia in these instances can be life-threatening.
Dehydration is another common issue when obstructions occur as more saliva than normal will be lost. If the horse is unable to drink due to the obstruction, this further increases the risk of dehydration.
Oesophageal tissues at the blockage site may also begin to swell and can become so irritated that they ulcerate. Scar tissue from this type of injury greatly increases the chance that the horse will choke again.
Important
Most blockages which do not clear on their own are actually ones at the distal end of the neck, and in these cases the swelling is more likely to be seen on the left-hand side of the neck in front of the forequarters. Despite a visible blockage, DO NOT attempt to massage the visible swelling up or down or give your horse any liquid in an attempt to drench him yourself – wait for the vet!
What should be done in a choke case?
A choking horse should not be allowed to eat or drink anything further and should be kept as calm as possible until the obstruction can be cleared. Ideally you need your horse to keep their head down to lessen the risk of anything entering the trachea and lungs.
“Some chokes resolve without treatment, but in many cases, a vet must administer sedatives or muscle relaxants to loosen contractions of the oesophagus. Water or other lubricants may be given by a nasogastric tube to flush the material out of place. If this procedure is done incorrectly, it can complicate the problem, so this is not a “home remedy” option. Surgery is usually not necessary but may be performed as a treatment of last resort. When the obstruction is cleared, the veterinarian will decide whether to administer antibiotics to prevent infection of the throat or lungs” (KER, 2008)
After initial treatment, feed and hay may be restricted for at least the first 24 hours. This allows the throat some time to rest and heal. Hay and feed would then be gradually introduced back by first offering only soaked hay or even chopped hay such as chaff and the wettest mashes of the horse’s normal feed.
Important
If your horse manages to clear the blockage on his own, do not cancel the vet visit. Your vet will need to examine your horse at some stage to assess if he is concerned about lasting damage, and if there are any predisposing factors that will need to be addressed.
What preventative measures can be taken?
Prevention will largely depend on the reason for choke. If it was due to poor quality, tough hay or plants within the horse’s paddock, then alternative roughage sources will need to be sourced, or the horse moved from the offending paddock. Also, if it was a foreign object, then it’s possible the choking episode would be a once-off if managed correctly.
For owners who feel that dry food was the source of the issue, adding soaked beet pulp to their feed, soaking cubes and even soaking meal type feeds, as well as soaking hay before feeding, can all help to prevent future episodes. These measures all add water to the diet, which can greatly help with lubrication during eating.
Alternatively, if the horse is known to “bolt” food, then management changes can be made as the first port of call and generally, these will centre around slowing the horse down while eating. This can be done by putting several large, smooth rocks in the feed bucket to keep the horse from being able to pick up too much food in one mouthful or by putting the food into a feed ball that drops feed out in small amounts when the horse moves the ball around. Similarly, cutting up feed and treats into smaller pieces can help them to more easily pass through the oesophagus.
The only issue with such measures is that it doesn’t stop the problem at the source, and it should be investigated as to why the horse is swallowing large quantities of dry material? And how can the situation be altered so that the horse ingests small mouthfuls of well-chewed and moistened food?
There could be several issues causing the ‘bolting’ of food, such as:
- being fed in a group. The horse may feel food must be eaten quickly to avoid competition, and so keeping the horse alone at feeding time may help.
- any kind of food restriction or being without food for any length of time.
- being very hungry when the food arrives. Providing some hay before meal times can ensure the horse is not anxiously awaiting the next meal and is fuller before starting to eat. Similarly, feeding lots of smaller meals can help.
Similarly, there can be issues meaning the horse eats food that is too dry, such as:
- competition for water in the paddock, meaning that horses don’t get to drink when consuming food.
- poor water quality, i.e. buckets not being clean, so the horse becomes reluctant to drink
- dental issues as if the horse is uncomfortable, then they may chew less and will therefore fail to produce adequate saliva (horses can only produce saliva when they chew) to moisten the food. Teeth should be checked once or twice a year.
- sick horses also often do not have the energy to chew their food correctly, so wetting their food can really help to reduce the risk of choke, at least in the acute situation.
Note: If the choke episode occurred after prolonged exercise or during intense lactation, it could be due to low saliva production and dry throat membranes related to dehydration, so always monitor the horse’s water intake and hydration levels.
Can avoiding certain types of feed help?
The answer to this is no. It would be wonderful if this was the case, then that type of feed could simply be avoided. However, the fact is that almost anything the horse swallows—grains, complete feeds, small pellets, big pellets, chunks of apples or carrots—can all potentially cause choke if the material is consumed in large amounts or is too dry to pass easily along the oesophagus.
It has been thought that pelleted feeds are the most frequent cause, but this has not been borne out in the research, and many yards have used such products for years with no issues. Fibrous hay or tough plants encountered while grazing may also lead to choke. In addition, some horses can pick up rocks, sticks, or other objects in the pasture, whether intending to eat them or just play with them, and these objects may become lodged in the oesophagus, causing choke.
Long-term
Most cases of choke thankfully resolve on their own or with simple tubing by your vet. However, if it takes a long time for the blockage to pass, long-term damage can be caused to the lining of the oesophagus. In each case your vet will advise you on the best approach.
References
- Kentucky Equine Research, 2008. KER research staff: https://ker.com/equinews/choking-horses-prevention-treatment/
- Contributors: Deidre M. Carson, BVSc, MRCVS & Sidney W. Ricketts, LVO, BSc, BVSc, DESM, DipECEIM, FRCPath, FRCVS. https://vcahospitals.com/know-your-pet/choke-in-horses