I respectfully disagree with MRoades… Not stressful so long as you’re not squeamish. I’m a retired equine vet tech and have assisted in many gastric scopings, including my own horse’s.
Yes the horse must be fasted and that can make them cranky, but frankly they survive just fine. If you don’t think you can withhold food for the duration, or are afraid someone might take pity on him and feed him despite your instructions not to, overnight him at the clinic.
Here’s how it’s done: Horse is put into position, whether that’s stocks or being held. Typically a nose twitch is applied after some light IV sedation. The scope is passed up a nostril (and they’re MUCH thinner than any NGT tube used like in the event of colic). The scope is guided, and there’s a camera attached so it’s even easier then going blind with a tube. The vet waits for the horse to swallow and passes the scope into the esophagus and into the stomach, watching as he goes. Then the scope is maneuvered as needed to see the stomach and search for any ulcers. It could take up to an hour, but most scopes are over within a half hour.
Just so you know what to expect, the stomach will have sloshing green digested material floating, and it’s lining is two separate colors. As a noob, this may freak you out, but it’s perfectly normal:
“oesophagus and the dorsal portion of the equine stomach are lined with stratified squamous epithelial mucosa, which has minimal resistance to peptic injury”. In other words, it’s supposed to be there because it protects the stomach from the digestive fluids in a healthy horse.
In order to clear the camera from some of the stomach contents, the vet will occasionally use a large syringe to flush water through the scope and over the camera. Yes, it’s a syringe, but it’s just water and no reason to worry. Perfectly normal.
All this is on camera as big as an old style TV. The technician usually ‘drives’ the scope and helps the vet position it to thoroughly exam the horse. Think of how the head of a cobra turns and arcs, very similar. Once the scope is in, the horse won’t care in 90% of the situations. The other 10% might fuss a bit if they are especially sensitive to things in their nose.
There’s a slight chance the horse might get a nosebleed if he flicks his head at the exact wrong moment of removing the scope. Don’t panic. Horses can bleed about a liter or two with no ill effect. THAT is hard not to react to, but still not a reason to freak out. It’s just disgusting to witness. Coagulated horse blood reminds me of The Blob circa 1958.
Horse is usually allowed to recover as he stands in the stocks, or he’ll take a short walk to a vacant stall if you go to the clinic. If he’s home, the vet simply closes the door of the stall and tells you not to feed him anything until he’s fully awake and any chance of choke is well passed. About an hour in most cases, more or less.
Relax. You and your horse will be fine.