/FTEN BATHING THE HORSE IS ALL THAT IS NEEDED TO CURB THE INFECTION.
Healthy, unbroken skin forms a secure barrier that keeps serious pathogens out of a horse’s body. When that barrier is compromised—by chapping and cracking, or the scratching prompted by itch, for example—bacteria may find a path to establish secondary infections. The culprit is likely to be a bacterium that is normally a resident on the surface of the skin, such as Staphylococcus aureus or S. intermedius.
“S. aureus is a common organism found on skin. If you are healthy, this small number of staph
bacteria on your skin won’t cause any problems,” says Rosanna Marsella, DVM, DACVD, of the University of Florida in Gainesville. “If you or your horse develop a skin disease, inflammation or damage, the staph bacteria increase in number, and this can lead to a bacterial infection. About 99 percent of the time, if you have skin disease, you also have a staph infection, which also significantly contributes to itchiness.”
When the staph bacteria infect the hair follicles, firm, pus-filled nodules form then develop into crusty areas. “This infection frequently causes scabs that many people think is a fungus on their horse,” says Marsella. “A true fungal infection is rare; what often looks like fungus is Staphylococcus. This is why you shouldn’t be using antifungal treatment, like iodine, on conditions like rainrot. It’s better to use benzoyl peroxide or chlorhexidine because you are actually trying to kill bacteria.”
Often, bathing the horse is all that is needed to curb the infection. “For these infections, clipping and bathing is often the basis of treatment,” says Marsella. “Sometimes just giving the horse a bath with a medicated shampoo will kill the bacteria, and then you can follow up with something soothing and moisturizing. This can make a difference and help keep the horse comfortable.”