Diarrhea in Horses

PetMD Editorial
October 01, 2008
Share this:

Diarrhea is not in itself a disease, but instead a symptom of many diseases, recognized when a horse's feces change in consistency from the normal firm, well-formed fecal balls to runny, liquid feces. Diarrhea can range from merely loose stools to completely watery in appearance. There are certain instances in which a bit of diarrhea is normal, such as a sudden change of environment or feed, however, long bouts -- those that persist more than a few days -- or severe forms of diarrhea is not normal and require veterinary assistance.

Symptoms and Types

There are many causes and types of diarrhea leading to a range of severity. Mild diarrhea may go unnoticed for long periods of time if the horse is always out at pasture. As the severity of diarrhea increases, you may see fecal staining underneath the horse’s tail. In general terms, diarrhea can be classified as acute or chronic. Other than the obvious change in fecal consistency, you may see the following clinical signs:

Acute diarrhea:

¨       Fever

¨       Lethargy

¨       Inappetance

¨       Loud gut sounds

¨       Dehydration

¨       Signs of colic (abdominal pain)

¨       Weakness

¨       Edema (fluid accumulation in lower limbs and underneath the abdomen)

Chronic diarrhea:

¨       Weight loss

¨       Poor, unkempt appearance such as dull eyes and rough hair coat

¨       Lethargy

Causes

As previously stated, diarrhea is a common symptom for many different diseases. Listed below are a few causes to some of the more common forms of diarrhea in horses.

  • Chronic Diarrhea
    • Parasites
    • Excessive ingestion of sand
    • Chronic Salmonella infection
    • Inflammatory or infiltrative bowel disease
    • Neoplasia (lymphosarcoma in the gut)
  • Acute Diarrhea
    • Salmonella infection
    • Clostridial infection
    • Potomac Horse Fever
    • Antibiotic-associated diarrhea
    • NSAID (Non-steroidal anti-inflammatory) toxicity
    • Assorted toxicities (i.e. arsenic, cantharidin, various plant toxicities)

Diagnosis

Finding the cause of the diarrhea can be a challenge and does require the intervention of a veterinarian if the horse is systemically sick or the diarrhea has been persistent.

Your veterinarian will first perform a thorough physical exam on your horse, taking note of any dehydration or other problems secondary to the diarrhea that will need immediate attention. Your veterinarian will then likely take a blood sample as well as one or more fecal samples. Depending on the clinical signs the horse is exhibiting, the vet may test the feces for parasites, or may submit the sample to a diagnostic lab to test for bacteria such as Salmonella and Clostridia. If the diarrhea has been chronic and inflammatory bowel disease is suspected, sometimes an abdominal ultrasound is recommended, or even an intestinal biopsy.

Treatment

Treatment for cases of diarrhea varies and depends on the underlying cause for the affliction. Typically for acute diarrhea, the horse will undergo electrolyte therapy, thereby re-hydrating the animal and restoring the fluids lost because of diarrhea. For parasitic diarrhea, a de-worming agent (anthelmintic) will get rid of the parasites. Bacterial causes for diarrhea can be difficult to treat, as are inflammatory bowel cases.

Certain types of chronic diarrheas can only be managed and not cured and severely acute cases of diarrhea can greatly debilitate a horse very quickly. Fortunately, such severe causes of equine diarrhea are not very common and the occasional cases of diarrhea caused by stress or a change in diet often cure themselves.

Living and Management

Diarrhea can often be a simple thing to cure. It is, however, important to pay attention to the signs and symptoms of diarrhea in your horse in order to seek treatment before it, or the more serious disease causing it, becomes severe.