The second senior horse I took in was a 27 year-old palomino gelding named Thunder. He had chronic diarrhea for years. While with the previous owner, the vet could not find a cause. They started him on a probiotic, which seemed to help. They even tried worming him with Moxidectin, which is the most potent of all wormers. (You do not want to get the dosage wrong, and it is not typically recommended for senior horses). They thought that perhaps the cause of the diarrhea was a worm that only Moxidectin could kill.
The year or two before I took him, I heard that he was having problems with diarrhea. I did some research and learned that if you have a senior horse with diarrhea the first thing to eliminate as a cause is the teeth. An equine dentist, who has extensive training beyond vet school can give a complete evaluation of the mouth and teeth. An equine dentist will catch things a general equine vet may not.
When I took Thunder into my care the first thing I did was take him to the dentist. The dentist said his teeth were completely worn out and could no longer chew hay. The molars in horses should be completely flat and when the top arcade of molars meets the bottom arcade it grinds hay. Thunder’s teeth were “cupped out”, meaning there was no longer a flat surface, but rather a cupped surface. When he went to grind hay he couldn’t. The dentist said that if large pieces of inadequately chewed hay were to get all the way to the colon, they could irritate it and cause diarrhea. It looked like that was what was happening with Thunder.
I immediately took Thunder off hay and fed him soaked hay pellets. Within a week his manure normalized, and there was no sign of diarrhea. I even weaned him off the probiotic, and the diarrhea hasn’t been back. It’s been 2 1⁄2 years.
I asked the dentist if the present condition of Thunder’s teeth was preventable.
“Yes,” he answered.
“When would have been the last chance to start seeing him before we would end up with worn out teeth?”
“Ten years ago.”
Why does this all matter? It’s cheaper to feed high quality hay than it is to feed hay pellets. It’s more convenient to feed hay than it is to soak hay pellets a few times a day. While I don’t regret a single moment figuring out what Thunder needed and then providing it, if different decisions were made 10 years ago, and the information was in the hands of the horse owner, then Thunder could have been spared the years of chronic diarrhea and the resulting toll it took on his body.
If you have a horse, consider seeing an equine dentist as part of your horse’s care team. Don’t wait until they are old and having serious issues. Prevention is key. The health and longevity of your horse depends on it. And the best part of all, you will have more years to enjoy your horse.


