Saturday night, and what should have been a quiet night after a long day out competing, is quickly turned into a night of concern and panic. Timmy the six-year-old thoroughbred gelding appeared to be fine coming off the float, but five minutes after being let go in his box, he is making retching motions with his neck and has green stuff coming from his nostrils. The longer Timmy is left, the more distressed he becomes, leaving his owners stressed and trying desperately to contact a veterinarian.
What has happened to Timmy is not an uncommon scenario, but it is a frightening one. A careful history taken over the phone and I am reasonably confident that Timmy has choke and instruct the owners not to give him any food or water, and I drive straight there. Whilst not a life-threatening situation in the short-term, it is hard to leave a horse visibly distressed any longer than necessary.
Choke in a horse is different to what we would expect with a person choking. A horse that is choking has food or a foreign body lodged in its oesophagus, the part of the gastrointestinal tract (GIT) that is responsible for moving food from the pharynx (throat) to the stomach. In people, choking refers to the airways becoming blocked, and the patient is unable to move oxygen into their lungs. When a horse has choke, it can breathe but nothing can pass from the pharynx into the stomach, including the saliva that is produced, resulting in the buildup of fluid that has nowhere to go other than back up through the nasal passages and out of the nose.
Horses can choke on many things; for Timmy it was one of the commoner causes, hay. Coming home after a hard day of competition, horses can often be a little dehydrated and hungry. The horse takes a big mouthful of hay, but doesn’t chew the food properly or release enough saliva to mix with it sufficiently to help lubricate the hay. Once they swallow the bolus of semi-lubricated hay, it becomes lodged at some point between the pharynx and the stomach.
Although the bolus can become stuck anywhere, it is more common for it to lodge in one of three areas along the tract where there is an anatomical or mechanical reduction in the ability of the oesophagus to dilate and let the bolus move through. The common sites are the mid cervical region (middle of the neck), the thoracic inlet (where the oesophagus moves into the chest) and the last part of the oesophagus just before the sphincter that opens into the stomach.
When the hay is lodged in the mid cervical region, it can often be seen or palpated, although this can be painful for the horse and cause it to tense its neck. When lodged at the thoracic inlet or near the stomach, it can’t usually be seen or palpated, and the location is estimated by how far a stomach tube can be passed before a blockage is met. Timmy had a blockage around the thoracic inlet, and I was unable to pass a stomach tube down very far before its passage was stopped.