Treatment outcome depends on the severity and the cause of colitis. For example, horses with C. difficile infection have higher mortality and complication rates than those with other forms of colitis, at least in California, says
Magdesian. Horses with colitis due to the group B Salmonella infections also have a higher mortality rate. "The severity of Salmonella infection seems to differ with the host response, but also the age of the horse. Group B salmonellae tend to be more virulent
than other groups, such as Group E," says Magdesian.
Thal says the nursing care is critical. "The colon takes a number of days to regain function. I understand that in severe
cases, the whole mucosa has to be regenerated before these horses start having a functional colon again. You've got to stick
it out during that time."
A positive outcome for colitis cases can be a toss-up. "Certainly getting the GI tract back to normal function can be a challenge,
but more often than not, it's the secondary complications we see that can be what, unfortunately, lead to a negative or unsuccessful
outcome," says Javsicas. "Horses that contract laminitis, but also those with thrombophlebitis and clotting disorders, are
at significant risk. Sometimes they'll get hematogenous spread of bacteria or fungus to their lungs, which leads to secondary
Because of the degree of insult, the time course to return the lower gut to good function varies from three to four days to
up to two weeks or more before you may see resolution of the diarrhea, says Javsicas. And then the horse can have ongoing
inflammation and alteration in the colon for a time after that. In short, it can take quite awhile to get back to a normal
For the general horse population, this condition can be very expensive to treat because of the time period and the complications
that may be encountered along the way. "Sometimes it can be hard to prognosticate for the owners, because you don't know for
sure what's going to occur," says Javsicas. "In my opinion, you're always more successful if you treat very aggressively from
the beginning. The client needs to be prepared for that."
Ed Kane, PhD, is a researcher and consultant in animal nutrition. He is an author and editor on nutrition, physiology and veterinary medicine
with a background in horses, pets and livestock. Kane is based in Seattle.