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What to do about Horses with Diarrhea

I have a 26 year old TWH that has chronic diarrhea. He had vet work done last year, when it first started, with his blood work coming back normal, fecal exam okay and teeth are okay. No feed or hay change. Actually, his stool will be somewhat normal, not firm apples but has some substance to them, for most of the time then about once or twice a month it gets loose to the point of liquid. I had him on ProBalance during some of this time period but it did not seem to affect his stool. He is now on Stomach Smoother but still having the same results as with ProBalance. His coat is shiny, he eats all his grain and most of his coastal hay (his preferred hay for 23 years) and is still very active. His weight is pretty much staying the same the last year. – GB

Dear GB,

Diarrhea is one of those conditions that differs from horse to horse. Because what works for one doesn’t always work for another, you just have to start somewhere, keep a good journal, and try different treatments until something works.

You’ve started in the right place: with your veterinarian. That is, ruling out some of the more common causes through a complete physical examination, blood work and fecal exam. Some uncommon causes of chronic diarrhea require particular tests of blood, feces and even GI tissues; you may have to specifically ask your vet to run these additional tests.

When experimenting with treatments, I recommend keeping a record of everything you try and sharing this “diarrhea diary” with your vet. Before you try anything though, I strongly encourage you to deworm your horse (no matter the result of the fecal) with Panacur PowerPac or Quest (if he’s not debilitated). Then give a product with ivermectin and praziquantel to ensure complete coverage of all internal worm species.

Next either try adding products to his diet or changing his diet, but not both at the same time, because then you won’t know which treatment worked! Since your horse has been eating coastal hay, you could switch him to another kind of grass hay or to alfalfa hay. You could also try changing his grain or replacing it altogether with a multi-vitamin/mineral supplement or ration balancer. Remember to make any diet changes slowly, over a two-week period, so your horse doesn’t develop additional problems like colic or laminitis.

Here is a list of products to try to see if they help. Give them one at a time, with your vet’s advice, and for at least 30 days:

Probiotics, prebiotics and yeast – to reinoculate and feed the “good bugs”
Kaopectate and Pepto-Bismol – coat, soothe, relieve!
Psyllium – in case the diarrhea is caused by inflammation from sand
Daily dewormer – to prevent gut wall damage from parasites
Digestive enzymes – such as amylase, lipase, cellulase and protease
Hindgut buffer – encapsulated or protected sodium bicarbonate
Digestive support – products with L-glutamine, Licorice, Oat fiber and oil
Plant extracts – adaptogens to help normalize the body’s systems

If none of these over-the-counter treatments work, you may have to go back to your vet and start trying prescription products. Here are a few that have worked for some horses:

Steroids – prescription immune suppressants
Antihistamines – prescription products that may work best with steroids
Antibiotics – prescription only since some antibiotics can worsen the situation!
Rheaform – a prescription product that reduces motility in the colon
Lomotil – prescription anti-diarrhea medication
Imodium – over-the-counter anti-diarrhea medication
Opiates – prescription narcotics related to morphine

Unfortunately, it’s not uncommon for a treatment to work for a few weeks or months then the horse’s stool gets sloppy again. And some horses never improve, struggling with chronic diarrhea the rest of their lives. Just be patient and thorough and hope for the best!

Lydia F. Gray, DVM, MA SmartPak Staff Veterinarian and Medical Director Dr. Lydia Gray has earned a Bachelor of Science in agriculture, a Doctor of Veterinary Medicine (DVM), and a Master of Arts focusing on interpersonal and organizational communication. After “retiring” from private practice, she put her experience and education to work as the American Association of Equine Practitioner’s first-ever Director of Owner Education. Dr. Gray continues to provide health and nutrition information to horse owners through her position at SmartPak, through publication in more than a dozen general and trade publications, and through presentations around the country. She is the very proud owner of a Trakehner named Newman that she actively competes with in dressage and combined driving. In addition to memberships in the USDF and USEF, Dr. Gray is also a member of the Illinois Dressage and Combined Training Association (IDCTA). She is a USDF “L” Program Graduate and is currently working on her Bronze Medal. Find Dr. Gray on Google+

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30 comments on “What to do about Horses with Diarrhea
  1. erica busch says:

    did GB ever find out what was wrong with her TB?
    my horse has the same exact symptons.

  2. Ellen says:

    My horse had chronic diarrhea for a few years, and we must have tried what seemed like every type of supplement or treatment program, with absolutely no results. What ended up completely curing the diarrhea was switching him from timothy/alfalfa hay to hay cubes for a few months, and then switching him to orchard grass. Turns out, the long stem timothy hay is very upsetting for his stomach. Who knew!

  3. Caitlin says:

    My horse has been on the regular version of SmartDigest for about 2 years now, and it has completely eliminated his diarrhea, which he used to get every summer and sometimes when we switched hay (vet said it was idiopathic – we couldn’t pinpoint a cause). No problems at all for the last year & a half!

    • SmartPak SmartPak says:

      What fantastic news Caitlin! We are so happy to hear that SmartDigest has helped make your horse more comfortable and eliminated the chronic diarrhea. Thank you for sharing your story!

  4. Sarah says:

    I’m confused on the deworming advice. Panacur (fenbendazole) OR Quest (Moxidectin) plus immediately give Ivermectin AND Praziquantel (Zimecterin Gold, for example, is combo product)? The Panacur Power Pac is 6X the price of Quest – what determines which to use? I’ve always thought that giving too much dewormer at once may stress the horse’s system – should all these chemicals be administered at the same time?

    • SmartPak SmartPak says:

      Hi Sarah – Great question! The Panacur PowerPack and Quest both control encysted small strongyles, which can be a difficult-to-diagnose cause of loose stool in horses. Your veterinarian can advise you on which product might be best for this purpose in your horse. Your product choice will then determine when to give the next dewormer, either four weeks if Panacur or twelve weeks if Quest. This is because of their different egg reappearance periods, or, how long it takesl worms develop into adults and start laying eggs again.

  5. Marilyn says:

    A 10 day course of Metronidazole worked for us after 6 years of struggling with chronic diarrhea.

  6. Pat says:

    Try adding alfalfa cubes to his diet. This simple suggestion from a friend cured my first elderly horse, and has worked for others I have since known, including a Morgan who had liquid diarrhea for 2 years and for whom nothing else worked. It can be as little as one “coffee can” a day; soaking the cubes also works for horses whose teeth are very poor.

  7. Nancy Brubaker says:

    I agree with the write up and if no health reason can be found another thing to consider in an aged horse is the fiber length of the forage. I would monitor the stool to see if the fiber in the feces is larger than normal. An older horse is not able to chew and crush the forage as is necessary for digestion. Digestion starts in the mouth and steps take place all the way to the colon. It is the job of the colon to absorb the fluid. Fiber length can affect the proper function of the colon. We are lucky to have so many quality senior diets. I have a 33 (estimated age, grade horse) year old gelding that has 3 molars left. These teeth are fine, but face it he only has 3. I recommend an equine dentist (the DVM type) the best senior diet you can get and chopped hay so that digestion is most likely to proceed with less work from chewing, and balance the diet to meet his work load (more calories and buckets of supplements are a waste of energy, time, and money if your horse can’t use them) Your DVM can help with this or a nutritionist at any Veterinary School. Your DVM should be able to help direct you to good resources. Good luck and I pray you have many more years of happy trails with your older horse.


    I have checked several postings and info and my vet about why do horses eat poop? I have had my horses checked and tested for worms,etc and I find one of my mustangs is eating his poop.I don’t know how long he’s done it because I’ve never seen him until recently doing it. There are other horses in another pasture that do it all the time but I feel it’s because they have nothing to eat in the field.

    • SmartPak SmartPak says:

      Hi Shirley, thanks for asking! There are a few theories why adult horses consume manure, called coprophagy. Your thought about the horse being bored without any forage could very well be right on. If your horse is consuming manure because there simply isn’t anything else to munch on, you could try extending how long he has hay in front of him while he’s turned out. Consider a slow feeding tool such as a hay net or hay bag, or you could even look into products that allow you to slow feed entire bales of hay. It might also be worth evaluating your horse’s diet with your veterinarian to be sure it’s meeting all of his nutrient needs. I’ve also included a link to our Equine Health resource talking all about coprophagy in horses:, I hope that’s helpful! – Dr. Lydia Gray

  9. Kara says:

    My 16 year old twh/ morgan gelding has allergies. It seems to bother him most when the weather gets hot and humid. The other day it got really hot and humid out and he got sick.His breathing rate was faster, as what happens when he has to deal with high humidity. He normally has runny stools ( we have had him for 6 years and he was vet checked when we got him), but now its watery. He isnt interested in his grain, and will eat some hay (not as much as usual) but will eat grass willingly. He lies down alot but does not roll, and when he gets up he moves normally, doesnt walk slowly or act like he is in any pain. I do not know of any vet that will bill me for services and at the moment i have no money to pay a vet to come out. What should I do?

    • SmartPak SmartPak says:

      Kara, Thanks for asking us about your horse. Veterinary care is an expensive but vital part of proper horse care. Guessing at how to help your horse without the benefit of actually seeing him and being able to perform a complete physical examination would be far too risky for your horse’s health. We apologize that we aren’t able to help more, and encourage you to visit for help in perhaps locating additional equine veterinarians in your local area. – Dr. Lydia Gray

  10. Julia says:

    My horse has had sever diarrhoea for the past six weeks now. The vet has seen him and did blood tests protein levels in normal range, faecal sample came back negative to c dificile and salmonella (however I understand this is only ever detected one in five). He has lost a huge amount of weight and is tucked up. Vet gave codeine 10 x 60mg twice a day these have run out and his stool is like water. I started him on steroids day 5 today and still no change. I don’t want him on these as I know the ending won’t be a happy one as they stop working after a while. I have contacted a herbalist who is sending me a mix of herbs to try but I fear it may be too late for my boy. He has never been ill up until this. He seems fine in himself other than the stomach upset. I asked to try antibiotics first before steroids but they said best not. I’m still not convinced that it isn’t the salmonella.

    Please help.


    • SmartPak SmartPak says:

      Hi Julia, I’m so sorry to hear about your horse’s situation. It sounds like you and your veterinarian have been working closely together to try and diagnose and treat this issue. Have you considered that it may be time to coordinate with a teaching hospital or referral center in your area for access to board-certified specialists and advanced testing procedures? As you’re aware, diarrhea in horses can have serious consequences, and we hope you’re able to find a swift, sure solution. – Dr. Lydia Gray

    • Sarah says:

      Julia; how I hope your horse is better; just wondering, has your vet tried GastroGard? It is expensive, but my horse was similar, I moved his hay to a grass hay only and alfalfa cubes, not soaked, and NO grain, but with 10 days of GastroGard his tummy was WAYYY better; and he was so much happier. It was like magic; I would really give that a try, but use the actual GastroGard, $50 a tube here, one tube a day for 10 days, and not the omeprazole, as it doesn’t work as well, though it is cheaper…
      After the gastrogard and food changes, his back muscles (where the saddle goes) had been sunken in and sad looking, but after they filled in and he looked so much healthier….

  11. Brenda Race says:

    I have a 33 year old QH that has liquid diarrhea again.It started last year with the weather changing to winter. My boy lost almost 300 # over a period of 3 months; I had the vet out. We did blood work and a fecal test. The only thing that showed up was that he had low protein so i was advised to put him on a protein supplement. I put him on horse manna vitality and probios. The diarrhea cleared up to the point that his manure had form but it was soft.He started gaining weight slowly. I got 240# back on him. We are now back to the winter situation. I have kept my boy on the 2 supplements all of this time. The liquid diarrhea has come back again with the same symptoms as this time last year prior to calling the vet.Do you have any suggestions?

  12. Robin says:

    Hi all! Like many of you I too have a horse with liquid diarrhea…Only here is the kicker… All my horses now have some sort of liquid diarrhea.

    History… Our 27 Year old quarter horse started with liquid diarrhea last year…After thousands of dollars on Pre…Pro…sponges… this that and the other thing…Nothing has helped. And yes the vet has been out MANY times and Cornell has been used He has not lost a lot of weight. We live in Upstate NY and use a series of blankets all year to keep him warm and comfortable. Not to mention we wash his hind end and clean clean clean where ever he is. NOW a year later our 24 Year old POA is coming down with the same symptoms…So here we go again…maybe something will work for him? who knows. To make matters worse we also have a 24 year and 11 year old Morgan…now with loose stool.

    My thought process with this now has to be something they all eat.. The 11 year old morgan is the only one that gets grass (for about and hour) in the summer. The POA had slightly foundered about 10 years ago and has not had grass. The quarter horse has not has grass since the liquid diarrhea last year, and the older Morgan is a little fatty and does not need the grass.

    They all get hay fed about 6 times a day, Mostly Crimped timothy with grass mixed. NO alfalfa.

    They also get fed HS 35 twice a day…started this about 2 years ago.

    My conclusion is its either the hay…maybe the preservative used…or its the HS 35. I know its a supplement and the reviews are all roses and rainbows…

    But its something they ALL eat…

    • Kathleen says:

      Robin, having a similar situation, have tried everything mentioned in above posts. My vet just had me start Rheaform. Manure is firm after 3 days…

    • Moea Goron Futcher says:

      Interesting Robin,
      Thank You for sharing. I have one who’s had diarrhea for months now and we (vets and I) can’t figure out what is causing it. I’ve been suspecting something in the feed at this point.
      Here is my question: what are they putting in our horse feeds exactly? When you think about it, there is no regulation at all.
      Mine are all on Triple Crown Senior. Too much molasses but I believe there is something else which has changed as several of my horses have had diarrhea, one is suffering more than the others.
      Shame SmartPak doesn’t offer BioSponge by Platinum Performance, or any of their other products for that matter. Bio Sponge is a savior for diarrhea when no vet can help! I believe it’s because Platinum Performance refuses to do business with SmartPak. C’mon Smartpak, make the trade happen! I still purchase most of my supplements from Platinum, so do all the FEI level trainers I know. Sorry guys!
      I’ve also noticed that SmartPak can’t help us in any of these blogs, they don’t get involved in offering advice, legally, they would be in trouble I suppose if they did. Shame however that all they offer is words of sympathy and links to other websites or advice blogs.
      So you are right Robin: It’s either the hay or the feed. I am veering towards the feed…

    • Mary says:

      Hi. I am having simular issues with my 29 yr old QH mare. It started when I changed hay providers. I think the new ones used heavy herbicides. Gave all my horses diarrehea. I really suspect so many of our horses are reacting to the chemicals used incorrectly in hay production and feed products. She is slowly getting better. The long timothy issue is helpful to know about. Thanks.

  13. darlene says:

    I too have a 24 yoqtr/Arabian with watery stools I havenoticed what does give him wtery stools Metamucil alfala sweet feed I have not found after several years and several vet visits what would help him he eatss well and drinks enough o ad he has to be miserable would take any suggestions

  14. Moea Goron Futcher says:

    Try Bio Sponge by Platinum Performance. It works. You have to however try to find the underlying problem, not easy I’m afraid. Could be allergies, food intolerance. I’ve owned horses who can’t tolerate alfalfa for example, gives them diarrhea. Could be climate, stress, farrier, other issues. Not an easy problem to solve I’m afraid. You have to turn every rock to find the solution.

  15. madeline shcadler says:

    My horse Captain has really wet poop and has had it froa bout 7 months and my trainer and i dont know what to do! we have tried sand clear and ulcer gard we are now trying a wormer, but i dont know what to do at this point. what should i do!!!

  16. malissa says:

    my 1 day old horse have diarrhea plz tell me what to give her to stop her diarrhea

    • SmartPak SmartPak says:

      Hello Malissa, We’re sorry to hear about what’s happening with your new foal! We’d recommend checking in with your veterinarian. There are many possible underlying causes for loose stool in newborns and it will be important to work with your vet to get to the bottom of the situation. We really wish we could provide a more helpful, detailed answer, but young horses do need to be managed carefully during such a critical stage of growth and development! – Dr. Lydia Gray

  17. Kath says:

    Hi would any one know why it is my horse has had chronic diarrhoea for years but each summer as soon as the grass begins to grow his stools darken and firm, he is no longer covered with soggy poo all over his butt daily and it literally is almost overnight. He will be much dryer all summer but the second the grass stops growing he will have diarhhoea. He is fed hay and his feed all year round. Two separate veterinarians have checked him and other than cushings he is very healthy, he has had antibiotics and steroids as well. Nothing makes a difference except the grass during the spring and summer months. He is turned out during the winter also with a stable open to the field so is never without grass, however has diarhhoea all winter and not in the spring or summer.

  18. Tammy Severson says:

    And here I thought we were all alone…well, we still are, with regard to our circle of horse peeps – none of their equines have chronic diarrhea. Ugh! Sakima is my 17 yo, QH/Morgan, Gelding, and he has had chronic diarrhea since (prior to) 7/2009, when we became partners. We run the board from good, single balls to brown water and flecks of manure. Sakima almost always has manure down his legs, in his tail, in his butt crack, etc. I am constantly scrubbing him and wrapping the upper portion of his tail with vet wrap. The flies and other insects just love his rear end .
    Like many of you, I have worked closely with my vet, had lab, blood and fecal workups done. We have stripped away all items except fresh water and hay (soaked & dry). Followed recommended deworming cycles and had our hay tested. He is on a dry lot, so he can only eat what I provide. He has a mineral block and a salt block. Here are the feed & supplements he takes daily: 2 cups of Standlee Orchard Grass Pellets, Purina Enrich Plus, Farrier’s Formula Double Strength Hoof pellets, Dumor Joint pellets, Devil’s Claw, Vitamin E, Probiotic mix and Peppermint Tea leaves (in steeped warm water). I use carrots, apples, sweet potatoes, beets, sugar cubes and strawberries as training treats. All supplements are “maintenance dose.” I worm him every 8 weeks (as directed by vet and fecal results). At present, we have been in the “cow patties to brown water with flecks” for 8 weeks. Sakima is eating, drinking, urinating, defecating, moving and acting like his usual self. He is not dehydrated, nor in distress. His teeth were floated in June, with no issues noted. He sees his farrier and chiropractor monthly. I have been told so, so many different things to try and do, but nothing has worked. The most recent recommendations were: Slippery Elm, Panacur PowerPac and consult an equine nutritionist. I would appreciate input, as I hate my fella being known around the trails as “the friendly horse with the sh+++y tail.” Thanks so much!

  19. Gerrett says:

    How much liquid imodium can you give a horse by pound?

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