Diarrhea in Senior Horses

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.

The day I picked up Thunder.  Notice the dirty hocks.  It is from the chronic diarrhea.
The day I picked up Thunder. Notice his dirty hocks from the chronic diarrhea.


6 days post diet change. Normal manure.
20 days post diet change. Notice his clean hocks. No more diarrhea.

18 thoughts on “Diarrhea in Senior Horses”

  1. Going through the same thing now with my rescue horse…. teeth are very worn down and very long fibers in her stool. Diarrhea for the last few weeks and have worked twice. Fecal egg count was negative so switching from soaked beet pulp to senior feed with alfalfa pellets to see if that does the trick. All soaked and gradually obviously…wish me luck. Love my old girl ❤️

    • I hope you find what works. It can definitely be some trial and error. I tend to shy away from senior feeds because they are grain based, and grain can cause problems for the gut long-term because of its inflammatory properties. Here’s a wonderful article on the topic: https://theequinepractice.com/why-horses-should-not-be-fed-grain/?

      I was pleasantly surprised with the soaked hay pellets. They’ve worked so well with weight gain and no diarrhea that I’ve never needed to go to grain.

      Here’s another article I recently wrote on feeding seniors that gives a more complete picture. http://seniorhorserehab.com/senior-horse-care-tips/

      Good luck with your rescue and finding just what works for her. She is lucky to have you!

      • What kind of hay pellet? Alfalfa or what? Do they have Timothy hay pellets?? Thunder has exactly the same problem as my horse, (his name is Thunder too!!) My horse quids very badly and has chronic diarrhea. I am at my wits end trying to fatten him up before winter comes. Help!!

        • Hi Nancy,

          I use soaked timothy hay pellets and soaked orchard grass hay pellets. It’s basically the replacement for hay. (You can also use soaked hay cubes. The pellets worked so well for me I never bothered with trying the cubes, but cubes are an option). I feed about 10-15% of the diet in alfalfa (assuming there’s no serious metabolic issues going on). For my Thunder he was 1000 lbs and maintained his weight on pasture and pellets. In the summer he ate 10 lbs of pellets per day (I split it between 2 or more feedings per day, the more feedings the better). In the winter it was 15 lbs. With this amount he maintained his weight. I did not give him access to any hay. His inability to chew it adequately is what caused the diarrhea for him.

          Here’s another article I wrote on feeding seniors that might provide some more info for you. http://seniorhorserehab.com/senior-horse-care-tips/

          Good luck. I’d love to hear how it goes.

          • Hello, I am so excited to try your suggestions. I got the Redmond salt block, and also some Timothy and alfalfa pellets. Will start the new program tomorrow. No grain!! I am saying my prayers and hope my Thunder gets rid of his diarrhea and starts to gain weight. Winter will be upon us soon enough. Will keep you posted and thank you very much with all my heart!!

          • Hi Nancy, I hope the diarrhea clears up quickly. For my Thunder it was better within 5 days of the new diet and no hay, and by day 10 the manure had been normal for several days, so I knew we were out of the woods. He was diarrhea free to the day he died nearly four years later. No matter what happens, everything your Thunder does is info that will steer you to the ultimate cause of the diarrhea for him. He sounds very similar to my horse, and it would be wonderful if these changes did the trick and you could relax and just be able to enjoy him. I’d love to know how it goes. Good luck!

  2. Hi Mary, Well my Thunder is now on day 15 (2 weeks into new regimen) and he still has very loose stools. Just giving him 5lbs orchard grass and Timothy pellets three x day (15 lbs total). The stools are a little firmer, but not nearly normal at all. I am going to continue this for another few weeks, with hopes he gets more “normal”. I may have to put him down as I feel it would be cruel to put him through another winter here in Michigan. He still doesn’t look much better either. He is active and has full pasture and eats\drinks well, but just can,t tighten up the stools. Will continue though. I still think your explanation of the horses gut makes good sense . Will update and thank you. Nancy

    • Ni Nancy,

      I’m sorry to hear this. I’m glad to hear that the manure is a little firmer. Has a vet seen him? Do they have any ideas? Is there something else in the diet he is getting a hold of that he can’t digest? This may sound like a bizarre idea, but could it be the grass? Another idea that comes to mind is I have fed nutritional yeast to seniors to help with the digestion of fiber. Another possibility is that something else is going on that is not teeth related. If I’m really stumped on something I’ll do biofeedback. Sometimes something will show up there that will point me in a direction to solve the problem. One more idea comes to mind, http://www.PlatinumPerformance.com has a protocol they do for loose stool that might help. They have advisors that will talk to you for no charge. How is Thunder’s demeanor? Is he still in the game? Does he have any ideas? If I come upon any other info, I’ll be sure to share it with you. Here’s hoping you find the cause. Good luck, and bless you for being willing to try.

  3. I Mary,
    This all started almost two years ago, Thunder colicked very badly and the vet came out every day for a week. He advised putting him down,but I wanted to work with him. It took about 4 months of continues care and he finally started acting like a horse again. However, he lost a lot of weight and has never been able to put it back on. The vets (I had two come out) could not find any good reason for this. He was dewormed, teeth overly floated(this was because he quided his hay). The third vet wouldn’t touch his teeth because the other two had filed them way too much. Bad things happen . With the compounded problem of not being able to eat well and severe diarrhea, he is not getting any nutrients, it just goes right thru him. Everything I feed him everyday is just a pile of runny loose poo on the floor the next day. He is very lively and active and I still ride him, just walk and trot him now. I don’t want to overtax him. He seems to enjoy getting out. He is a wonderful trail horse. I am very sad for him and am stressed with the thoughts of putting him down. I am going to continue this feeding regimen for a few more weeks and then will have to make some decision. Thanks for the pointers, not sure what to do about the grass, he seems to be able to eat that without too much quiding. Will call Platinum Performance and talk with them. Thanks for the info.

    • Hi Nancy, It sounds like you are in the thick of it. When I’ve been in a position similar to yours, I really include the horse in everything I am doing and trying. I’m also very clear for myself what I am capable of doing and what I’m not, and if other people are available to help me or not. If a horse is mentally still in the game, and I am too, then we keep going. If one of us is not, then I have very frank discussions with the horse. I’m also in no hurry to “fix” anything or make it look presentable to the outside eye. Other people may not understand or agree with your decisions. That’s ok. All that matters to me is what does the horse have to say and what am I capable of doing. Each of us, the horse and I, own our individual parts.

      I do recall one time seeing straight diarrhea (no constitution at all to the manure balls) in a horse that had cancer and couldn’t keep any weight on. Mentally he was still there and enjoying his life. I’m sure that at some point he either died on his own or his owner euthanized him.

      There is also a facebook page called Holistic Horse Healthcare that may have some ideas.

      As long as a horse is still engaged in life, I am an optimist. There’s something to work with. I also know that all of us will die one day. I’ve compiled everything I’ve learned about dying and hospice, from the senior horses who have died in my care, here: http://seniorhorserehab.com/death-and-dying/.

      And just in case no one has the courage to say this to you: You do not need to put your horse down. When it’s his time to go, he is capable of dying all by himself. If he needs something from you, he is capable of letting you know. If you’re stressing about it, the time is not now. You and he are in this together, and you don’t have to take it all on by yourself.

      I will continue to hope for the best, but I think Thunder has already hit the jack pot no matter what happens. He has you right by his side and that is a huge gift only you can give.

    • Dear Nancy, you’re welcome. This journey you are on with Thunder has a life all its own, with its own ups, downs, twists and turns. Take it one day at a time, even one moment at a time. It is all precious, even when it may not be going quite how we want it. Be sure to take care of yourself too. Thunder is one lucky horse to have such a courageous owner. Here’s wishing you peace, comfort and strength for the journey.

  4. Hope you’re still doing this blog since the last dates were in 2019. I have a very old horse, vet estimates range from 35 to 40! Her teeth were floated 2 years ago & she was doing quite well on soaked beet pulp & senior feed. No hay due to excessive quidding. I’ll spare you the story of why she was suddenly put on alfalfa hay but after a week the results were a disaster. Major diarrhea even after going back to the beet pulp & senior feed. Other than this she’s spry as can be & totally engaged in life. I’ve tried OTC diarrhea remedies with no luck. Vet has no idea or suggestions. Help!

    • Thank you for your question. If I understand correctly, she had diarrhea after her diet was changed to alfalfa hay (after it had previously been soaked beet pulp and senior feed). Then you switched her back to the beat pulp and senior feed, but the diarrhea did not resolve. Is that correct? How many days was the alfalfa diet, and how many days back on the old diet?

      In general, any time a horse can’t digest something, it can cause diarrhea. In a senior with poor teeth, the usual culprit is hay that they are not able to chew adequately. I’m always shocked to learn of veterinarians who do not know this. From what you are describing, I’d be tempted to go to a 100% forage based diet. No grain, no senior feed, no oil, no nothing, but just straight forage. Since she can’t chew hay, then I’d do soaked hay pellets or cubes (and pasture if it’s available) and that’s it. See what happens over 1-2 weeks. I tend to stay away from grain of any kind, because long-term use can cause digestive issues. Meanwhile, I might consider a ration balancer that is not grain-based to make up for the nutritional deficiencies in the forage. A probiotic is another possibility that typically won’t hurt anything. For me, I’d be wanting to go to a “clean” diet, see how the body responds, and if it doesn’t resolve the diarrhea, then start looking at what else could be causing the diarrhea. Good luck.

  5. I just wanted to say I am very appreciative of this post, purchased a few senior horses from a gal that rescued them from the Kill Sale.. Chronic is the eldest at 18 and had neglected teeth.. Noticed diarrhea and long stem poops instead of the normal horse manure and grew concerned. I happened to do a google search and your post on the subject came up and I am so grateful it did.. I followed your advice and already with in a week his poop was returning to normal, and its plain to see he can not tolerate consuming regular hay and it must be chopped and soaked… Have also decided to start weaning him and the other two( MJ is a x Racehorse and 15 and Haze is blind and 12) really do appreciate a more simple regimen to feeding this crew.

    Would this also be good for Donkeys? I have a senior Donkey and her Son that we were gifted when their elderly owners sold their farm up the road and we took them in.


Leave a Comment