Diarrhea in Horses 101: Causes, Treatment, and Recovery

Most images of horses involve running, jumping or simply grazing in an open meadow. From such scenes, it is hard to imagine these steeds in anything but excellent health. Yet equines suffer all sorts of maladies along with the rest of the animal kingdom. From broken bones to immune disorders to peptic ulcers, many horses suffer their fair share of pain and discomfort. Yet one symptom often escapes the notice of horse lovers: diarrhea. Whether acute or chronic, diarrhea in horses can suggest a minor upset or signal a serious affliction. Below are possible diagnoses and some commonly prescribed treatments.

Equine Diarrhea Effects

1. Acute Diarrhea

As with many species, diarrhea in horses is most easily noticed in the loose stool or semi-liquified fecal matter. Yet the symptoms do not end there. An afflicted horse may run a fever and suffer from dehydration. Loss of appetite often accompanies these symptoms as do noticeable sounds emanating from the gut. In addition, weakness and fatigue are evident and fluid may build up around the lower extremities. Veterinarians identify abdominal pain as another significant indication of intestinal distress.

2. Chronic Diarrhea

Chronic, or ongoing (i.e. lasting beyond a couple of weeks), diarrhea shows up in additional manifestations. For example, the equine will begin to undergo conspicuous weight loss. Moreover, its coat will take on a rougher, more mangy appearance. Even they eyes will evidence dullness and lack of vitality. The lethargy that shows in acute diarrhea is even more pronounced in the chronic form. Veterinarians stress to horse owners that diarrhea in horses is a medical emergency requiring immediate attention. As these problems demonstrate, equines are in danger of dying should they go unattended.

Health Conditions Causing Diarrhea

Diarrhea in horses is not a spontaneous ailment. There is always an underlying pathology. Common causes are listed here.

1. Salmonella

While salmonella can adversely affect many species of animal, it is linked to diarrhea in horses through Salmonellosis, a gastrointestinal disorder brought on by a bacterial infection. Often, a horse will eat the contaminated fecal matter of another equine and thereby contract this disease. Yet salmonella is also transmitted through feed, forage, bridles, saddles and, yes, human hands. Many symptoms noted above accompany Salmonellosis. Those horses that are stressed or have compromised immune systems will shed salmonella organisms, passing them to other steeds. Some untreated mares have suffered abortion from Salmonellosis.

2. Clostridia Poisoning

Clostridium difficile is a bacterium that causes enterocolitis in various livestock species. This is a toxic infection of the colon, producing severe inflammation and, among other difficulties, diarrhea in horses. Ironically, c difficile–as it is known–often spreads from antibiotic treatments, some of which suppress the very bacteria which inhibits the proliferation of clostridia. This infection works very fast. At times, death arrives before any diarrhea is detected. Like tetanus, this bacterium is present in most soil but the infection is triggered by antimicrobials and lesser known causes.

3. Potomac Horse Fever

Otherwise known as equine neorickettsiosis, Potomac Horse Fever was originally thought to be confined to mid-Atlantic states. Later discovered elsewhere, this disease normally occurs during the warmer times of the year and presents itself near rivers and streams. In addition to diarrhea in horses, Potomac Horse Fever is marked by laminitis, a painful inflammation of the hoof area. Unlike the previous illnesses, this is rarely found in foals so they generally avoid vaccination until five months of age. The fact is that the effectiveness of vaccines for Potomac Horse Fever is the subject of much debate.

4. Parasites

Gastrointestinal parasites are a recurring agent of diarrhea in horses. Among the regular offenders are tapeworms, pinworms, stomach bots, roundworms, small strongyles and large strongyles. These can each cause slower maturation in young horses, colic, irregular performance and–on occasion–fatalities. Such nematodes are stealthy and silent until, of course, the complications develop. Worse, some parasites not only perforate intestinal lining but also disrupt healthy pulmonary activity. Strong prevention techniques include keeping pasture grass shorter than eight inches; regularly raking pasture to reduce manure piles; allowing other livestock to graze horse grasslands, and keeping water sources free of contaminants.

Treating the Causes of Diarrhea

While proper care and feeding can help a mare or stallion recover from diarrhea, sometimes the disease requires stronger measures.

1. Antibiotics

There is growing anxiety regarding the use of antibiotics in livestock. Some informed voices believe these medicines are overused and contribute to new strains of resistant infections. Nevertheless, the danger diarrhea poses to equine health mandates the availability of these drugs when the underlying organism is a threat. To be sure, antibiotics should be prescribed by a veterinarian and should not normally be employed as a preventative. As an intermuscular injection, an antibiotic is administered in the chest, hindquarters or neck. Rotating the area of injection with each shot is a best practice.

2. De-Worming Agents

As observed above, effective de-worming begins with pasture management and clean facilities. Beyond these measures, a fecal egg count (FEC)–i.e. determining the number of parasitic eggs per gram of manure–helps to determine the correct medication and its appropriate dosage. The FEC is an annual or bi-annual event unless the horse is given to parasitic infections. The results reveal the level of contamination so owners and vets can make the optimal medicinal choices.


Keeping a horse adequately hydrated is important as it recovers from the ravages of diarrhea. Clean surroundings and pure feed/forage also help the animal resume normal intestinal function. As with any convalescence, the equine does well by resting and avoiding over-exertion. If possible, isolation from other horses and livestock allow the steed to regain total health without the threat of another infection. On-farm vet care is preferable to trailer trips as the latter can heighten stress levels and hinder recovery. Gently easing the animal back into its normal routine is a good rule of thumb.

Image source: depositphotos.com

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