An episode of choke is extremely stressful for both horse and owner.
Unlike the situation in humans, choke in equines is not an immediately life-threatening condition. This is because in humans the trachea (windpipe) is blocked in a choking situation, whereas in the horse with choke the oesophagus (the muscular tube leading from the mouth to the stomach) is blocked. Therefore the airflow into the lungs is not compromised in choking horses in the same way that it is in in choking humans.
Mechanism of disease
Choke occurs when food or a foreign object get stuck in the muscular oesophagus of the horse. As the oesophagus contracts to force food down into the stomach, 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 quickly as possible. Once the food has hit the stomach which has a much larger diameter, it is unlikely to cause problems again as it passes through the rest of the digestive tract.
There are several causes of choke. The most common are as follows:
- Horses not chewing their feed properly, either due to dental issues or simply wolfing their food down too quickly.
- Horses not producing enough saliva to wet their food sufficiently when they are eating.
- Partial obstruction of the oesophagus due to scarring from an old injury, or a tumour.
Horses usually show signs of choke pretty quickly after the blockage occurs.
The horse may appear uncomfortable, stretch their neck out and swallow repeatedly.
To try and clear the blockage they may cough, retch or gag.
The most definitive sign of choke, however, is fluid coming out of the nose and mouth.
The fluid is often green or brown and there may be reasonably large volumes.
Sometimes particles of food can be seen in this fluid.
This fluid is produced, not because the horse is vomiting, but because saliva produced by the horse cannot be swallowed due to the blockage, so it builds up above the blockage and when it has built up to a level that can no longer be contained it emerges from the nose and mouth.
The fluid that emerges is normally green or brown in colour due to the colour of the food material in the oesophagus and mouth.
If the blockage is particularly large in size, you may also notice a visible swelling on the neck of your horse.
More general signs of stress and discomfort will also be seen, such as sweating, pawing and box walking.
Did you know?
Most which do not clear on their own are actually blockages at the distal end of the neck – and in these cases a swelling is more likely to be seen on the left hand side of the neck in front of the forequarters.
As soon as you suspect choke, remove all feed and hay so your horse can’t consume anything else, and call the vet immediately.
While you wait for the vet try and encourage your horse to remain calm, ideally with his head down.
This will lessen the chance that he coughs anything up, as once a horse coughs matter up it can in some cases find its way down into the trachea and lungs and cause aspiration pneumonia. This can be a life-threatening condition.
If your horse does 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/she is concerned about lasting damage, and if there are any predisposing factors that will need to be addressed.
Another option while waiting for the vet is hand-walking – hand-walk your horse for 10 to 15 minutes, with 10 minute intervals spent in the stable.
DO NOT in this time attempt to massage any visible swellings up or downwards, give your horse any liquid in an attempt to drench him yourself or attempt to pass a stomach tube yourself.
Diagnosis and treatment
A diagnosis of choke is usually made when the vet examines the horse, as the signs are pretty conclusive. However, in some less clear-cut instances, the vet may pass a tube down into the oesophagus (through the nostril) to assess where the blockage is. An inability to pass the tube any further shows that the blockage is in that site, which can give the vet some indication of how close the blockage is to the stomach. Some of the tubes used are fitted with a camera to allow the vet to visualise exactly what the cause of the blockage is.
In order to clear the blockage your vet will flush water down the tube and probably syphon the fluid back out again. This is often repeated several times, with it sometimes requiring one or two buckets of water for the blockage to clear. The blockage tends to break up and clear that way, rather than all moving at once.
After this, your horse will likely be put on a restricted diet by your vet for at least the next few hours and perhaps days. Over the next few days you will need to monitor your horse closely for signs of re-choking.
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.
Choke cannot be prevented entirely but there are certain things that we can all do to reduce the risk of our horse being affected. Some of these prevention methods are as follows:
- Schedule regular dentist visits – especially for senior horses.
- Switch to a senior feed when necessary as these feeds tend to be easier to chew and digest.
- Wet food so that it has a smoother passage through the oesophagus.
- Chop up treats like carrots and apples into smaller pieces so that they can easily pass through the oesophagus.
- For horses that tend to bolt their feed, place one or two large river stones in the bowl so that the horse has to pick around them to get to his food.
- Schedule as much paddock time as possible or at least make sure that your horse has access to grass 24/7. Having constant access to grazing should reduce the likelihood of him bolting his food.