Although originally isolated to the Potomac River area in Virginia and Maryland, Heidmann says Neorickettsia is endemic in other regions throughout the United States and recommends you talk to your veterinarian about its occurrence in your area. For this reason, PHF is most common around bodies of water. Neorickettsia risticii-the causative agent of Potomac horse fever (PHF)-are bacteria found in parasites that infect freshwater snails and caddisfly and mayfly larvae. “We also see it in adult horses, especially in horses that have been treated with antibiotics.” “Sometimes we’ll see it in very young foals, even in the first day or two of life, causing diarrhea and colic signs,” Nolen-Walston says. Fortunately, it responds to the antibiotic metronidazole.Ĭlostridium perfringens is a common cause of foal diarrhea. “If the healthy flora in the horse’s body is thrown off by even a small change in diet, or something bigger like a colic episode, or antibiotics, then Salmonella can grow up in its place.”Ĭlostridium difficile, which lives in the environment, also gets a foothold from gut flora imbalance, usually due to the horse having been treated with antibiotics for another infection. “Horses can also carry Salmonella and not have any symptoms, so they can pass it to each other,” he adds. “Those are the cases where horses get IV (intravenous) fluids and plasma for two to three weeks until their bowels start to heal. “The Salmonella species that affect cattle are the most pathogenic, and the secondary effects on the intestine on a microscopic level are very severe,” he says.
Peter Heidmann, DVM, of Palm Beach Equine Clinic, in Wellington, Florida, says most Salmonella species are associated with livestock and birds.
Salmonella and Clostridium species are the most common bacterial offenders. Sometimes harmful bacteria enter the horse’s system other times something upsets the balance of normally present bacteria, allowing “bad” bacteria to thrive and overtake the good. Infectious Causesīacteria are one major source. But when toxins, sand, parasite larvae, and infectious agents such as bacteria and viruses get involved, it becomes a lot more serious. Some horses develop mild diarrhea when their diet changes, and it’s not generally a big deal. What Causes Diarrhea?ĭiarrhea can originate from a wide array of conditions, some not even related to the digestive tract. What causes diarrhea, and why? What treatment options exist? When can you self-treat safely? At what point should you call your veterinarian? Can you expect a definitive diagnosis - or is a diagnosis even important? Read on for the definitive scoop on runny poop. “But horses have a rather delicate large intestine that has a very minutely balanced flora of bacteria, and something that disrupts that balance can cause diarrhea even without a particular pathogenic (disease-causing) bug being there. ACVIM (LAIM), associate professor at the University of Pennsylvania’s New Bolton Center, in Kennett Square. “In humans, diarrhea is generally benign,” says Rose Nolen-Walston, DVM, Dipl.