Equine colitis: Causes, consequences and management challenges for veterinarians
Paynter, a 3-year-old colt, fought down the racetrack's lane, just missing the win by a neck to Union Rags at the Belmont Stakes on June 9. On July 29, he fought again, this time pulling away from the rest of the field at the top of the stretch to commandingly win the $1 million Haskell Invitational.
But sadly those races would not be his biggest fights. After he contracted a fever and pneumonia, Paynter was sent to the Mid-Atlantic Equine Medical Center in New Jersey and administered fluids and antibiotics on July 31. Shortly thereafter, he was shipped to Belmont Park in Elmont, N.Y., to recuperate and then to Saratoga Race Course in Saratoga Springs, N.Y., for a shot at the late summer derby, the Travers Stakes, Aug. 25.
Equine colitis overview
According to Douglas Thal, DVM, DABVP, Thal Equine LLC, Santa Fe, N.M., the equine digestive tract is a complex and fragile system that is easily disrupted. One sign that the colon is disturbed is the development of diarrhea, from mild to severe—even life-threatening. Once colon health is disrupted, its ability to carry out the normal functions of digestion and absorption are critically affected.
"Serious colitis causes severe diarrhea, which accounts for huge water loss, and can cause rapid loss of fluid from the circulatory system," Thal says. "This leads to a vicious cycle of low blood pressure and reduced blood flow to vital organs and circulatory shock, which can quickly result in death if untreated."
Colitis disrupts the integrity of the mucosa. Once a horse is affected, the ability of its colon to absorb water and nutrients—the colon's normal function—is compromised. In addition, major shifts take place with respect to the bacterial population needed for normal gastrointestinal (GI) function.
GI inflammation can take several forms. It can occur as segmental disease, limited to one section of the GI tract, or as more diffuse, nonsegmental disease, says K. Gary Magdesian, DVM, DACVIM, DACVECC, DACVCP, professor at the University of California-Davis School of Veterinary Medicine. Magdesian notes that the illness is called:
In general, the younger the horse, the more likely it is to have primarily small intestinal involvement. But even mature horses can have any of these forms, including diffuse disease, disease limited to the small intestine or disease limited to the large colon.