This is me, your horses stomach; youre looking at my glandular region and, at the bottom is where the small intestine starts. The upper halve of my stomach is behind us (the squamous region, the scope has already passed through), but this is the business end its where I produce acid and enzymes, to process the feed, and also mucin to protect myself! The mucin coats my walls across the pylorus and somewhat up into, but not all of the squamous. As you can see, Im a nice, healthy colour, smooth and clear of any lesions or surface abnormalities, ready to do my job.
Im the regulator of the whole digestive system. During the day, up 12 times my volume passes through me, but I control the rate at which it passes into the intestine. Whilst it is with me, I ensure the acid from my cells mixes into the chewed, buffered food; at the same time, my partners both my enzymes and specialised microbes start the process of breaking down the food for the intestine to absorb. Food leaving me is at the right consistency, level of digestion and acidity for the powerful duodenal enzymes, and microbes, to carry out the next stage of digestion; ultimately, this impacts on the condition of fibre reaching the hindgut to optimise slow energy release.
All down to me!
So, all fine, you would think. But I can only work with what I am given and there are situations where that is less than ideal, and that can cause problems.
These situations may come from different sources. If my horse is stressed, if hes not eating for whatever reason then I will be empty! And that is not ideal. I cannot turn off acid production at will and if there is no feed in my stomach there is nothing to soak it up. This disrupts my stomach microbes, and the more acid-loving ones dominate, and this can promote pathogens that can damage me. Add on stress, then my mucus may dry up, allowing those pathogens access to that nice pink surface!
And thats not all. Some feeds, especially those hard feeds that are rich in starch, can cause further problems. They arrive poorly chewed and buffered, and my acid doesnt absorb onto it. Worse, those acid loving microbes digest the starch and produce more acid, encouraging more …. and so on! Not only does this mean Im sending a more acidic mix into the intestine, but there is excess acid sloshing around me. Exercise, an empty stomach and stress all mean exposure of my walls to acid burn which can lead to ulceration and even infection; they call it EGUS. And it hurts! Furthermore, starchy feeds will increase insulin release and one of insulins jobs is to impact acid secretion and so it goes on! Although my mucus mainly protects me in my glandular region, there can be damage to other areas of me, and even further down the gut. I can end up like this:
So how can I make sure this doesnt happen? I am designed to process a continuous flow of well-chewed, moist feed so it leaves me well conditioned. To keep me safe, this needs to happen all the time. If Im to process starchy feeds, it needs to be done little and often, alongside forage, so I can cope. If there is to be exercise, dont stop feeding me, but give me a little forage to work on and to keep the acid soaked in. If there is stress transport, scary things or behavioural issues, try keeping my horse calm; this keeps me calm and I can carry on producing the protective mucus. If I get thrown out of kilter, not only do I suffer, but the whole of the intestine does, too!