Horses are trickle feeders, designed to eat fibre all day long, rather than consuming large meals less frequently. Fibre digestion takes place in the hindgut where a population of micro-organisms break down the fibre, in a process called fermentation, to provide a source of slow-release energy. Fermentation requires a healthy population of bacteria in the hindgut. Today, horses do not spend as much time grazing as they used to, and are often fed several large meals of concentrate a day, and this can affect the health of the population of the hindgut bacteria.
The stress of this unnatural regimen along with other stresses inherent in the lives of domestic horses, like transport and management changes can cause an imbalance in the good and bad bacteria in the hindgut leading to a decrease in the pH and inflammation of the gut wall. This results in a number of problems including diarrhoea, behavioural changes, colic, weight loss and generally poor performance. However, often the symptoms are initially milder: for instance, a horse may not like having their girth fastened; or they may resent the application of the rider’s leg; or they may dislike being groomed under the stomach.
It is vital that at the first sign of hindgut distress you contact your vet, as your vet needs to rule out other issues like gastric ulcers which require their own specific treatment. Your vet will be best to advise you, but treatment of hindgut distress often requires predominantly management changes. Horses with hindgut problems will need more turn out and more grass and hay for fibre. If concentrate must be fed, the feeds must be split into much smaller meals to avoid overloading the hindgut. Your equine nutritionist will be best able to advise you on the way forwards. However, it is worth bearing in mind that even in horses without hindgut distress, management changes such as more turn-out time and increased fibre intake with smaller concentrate meals, will improve their overall well-being both physically and mentally.