Diarrhea in Horses: More Than Just A Mess
Diarrhea is a relatively common problem in many animal species (including people). It's often mild and typically goes away on its own, and is more of a cosmetic or convenience problem than a serious health concern. However, that's not necessarily the case in horses. Although horses can get mild diarrhea that gets better on is own, severe diarrhea (colitis) is a very serious problem that can even be fatal. There are many potential causes of diarrhea in horses, including Salmonella, Clostridium difficile, Clostridium perfringens, Neorickettsia risticii (Potomac Horse Fever) and Lawsonia intracellularis. It is likely that numerous other bacteria can also cause diarrhea, but we just don't know how to diagnose them. In fact, a specific pathogen is identifed as the cause of diarrhea in horses in less than 50% of cases.
Diarrhea can be rapidly life-threatening in horses. Some reports have described fatality rates as high as 40%, however these are based on cases from referral hospitals which presumably treat the sickest horses. Nonetheless, this high fatality rate needs to be taken seriously. In severe cases, death may occur in less than 24 hours, and may be due to the intestinal disease itself, or any number of complications that can accompany colitis.
The picture (left) is of the intestinal tract of a six-month-old foal with severe diarrhea that threw a blood clot to one of the major blood vessels suppling the large intestine, killing that section of the gut (the dark purple/black intestine in the picture), and the foal. Laminitis (founder) is also a common complication.
There is no way to completely prevent diarrhea from occuring in horses, but some basic measures should help reduce the risk:
- Only use antibiotics when absolutely necessary, and only when prescribed by your veterinarian. Antibiotic-associated diarrhea is big problem in horses.
- Avoid sudden management changes, such as feed changes and transportation, as much as possible. If something needs to be changed, try to introduce the change(s) as slowly as possible.
- Isolate new arrivals so that the risk that they will introduce pathogenic bacteria like Salmonella to other animals on the property is reduced.
- Have a good basic infection control program in place to reduce the risk of transmission of infections of all types.
- Immediately isolate all horses with diarrhea, and contact your veterinarian.
