A common condition which is seen in horses is that of hind gut or colonic ulcers (often referred to as Right Dorsal Colitis). Ulcers develop when the mucosal lining of the gastrointestinal tract thins and the microbiome becomes out of balance. Gastric ulcers were previously discussed in the Upper Gastrointestinal article of this series. Colonic ulcers are seen less frequently than gastric ulcers, and are more commonly seen in performance horses than in non-performing horses. These ulcers can be caused by large quantities of undigested starches and sugars (commonly contained in processed grain) reaching the colon and producing lactic acid. The lactic acid causes a drop in the pH of the colon and may result in a decrease in the production of mucous which is normally present as a protective barrier of the hind gut membranes. Stress associated with the work environment of the horse can lead to the release of excessive steroids within the body, resulting in ulcer formation. As well, the administration of NSAIDs such as Bute or Banamine may also lead to the development of these ulcers.
Clinical signs of hindgut ulcers include lethargy, intermittent decrease in appetite, fever, bouts of colic, diarrhea, edema on the belly, weight loss, poor body condition and decreased work performance. There are a number of methods that can be used in an attempt to diagnose colonic ulcers. The presence of any of the clinical signs listed can help to give a presumptive diagnosis once other causes such as gastric ulcers, infectious diseases and cancer are ruled out. Blood work, peritoneal (belly) fluid analysis, examination of the feces and abdominal ultrasound are all additional diagnostic tools which can be used to determine if ulcers are present.
Treatment of horses suffering from colonic ulcers is a multi fold process, generally requiring a combination of changes in diet, environment and training/travel in order to reduce the underlying stress which is most likely the cause of the ulcers. Decreasing the size of meals and increasing the digestibility of the food can aid in the healing of the gut. Allowing frequent short grazing periods throughout the day to reduce the stress associated with stall confinement may also assist in healing. Discontinuing administration of NSAIDs is also a key component in the treatment regimen. Balancing the gut microbiome is extremely important to the health of the digestive tract. Replenishing the gut flora with a diversity of probiotics and feeding them with prebiotics as they travel to the hindgut is the first step to increasing the chances of healthy assimilation of food.
Horses generally respond well to the combination of dietary and environmental changes, a reduction in stress, and appropriate medications and/or therapeutic supplementation over a period of weeks to months. The key concept to remember is that the longer the ulcers remain undiagnosed and untreated, the longer the recovery period will be.