From the gut to the foot- how an event that starts in the gut has the potential to cause the collapse of the foot -putting together the pieces and the relationship between colitis/colic/overeating grass/carbs, how science is starting to make the links often by using human research for comparison.
The horse is designed to eat grass trees and shrubs but lacks the ability to digest structural carbohydrates however there is a part of the gut which is able to ferment these structural carbs and with the help of millions of micro -organisms the horse is able to harvest an energy supply such as volatile fatty acids and lactate.
The horse G.I. tract contains millions of very complex micro -organisms with up to 500 different strains or families of bacteria. The horse produces a massive 80% of his energy from the fermentation process as compared to the human yield of 15%. The gastro intestinal tract of the horse is also susceptible to colitis and colic or colic like symptoms followed by an over eating event which frequently ends in a bout of laminitis.
Excessive carbs or grass increases the risk of undigested food making it into the hind gut and as the horse has limited means to deal or process the excess there are bound to be repercussions. The over- eating event has previously been compared by veterinary researchers to IBS in humans, again poorly/part digested food reaching the intestines is thought to be the cause of the inflammation. Like horses some people are more susceptible. In both humans and horse there is a rise in bad bacteria such as enerobacteria (Proteus and Klebsiella) and a decrease in good bacteria lactobaccilli and bifidobacteria. Humans with IBS have an increase in sulphate reducing bacteria and 63% of humans with IBS/gastrointestinal disease including bowel cancer show an increase.in fusobacterium as do horses with colitis/laminitis.
Fusobacterium are common pathogens in gut mucosa and some forms are known to be inflammatory and invasive taking over and colonising areas of the G.I tract. Fusobacteria are found in large amounts in horses with colic/ diarrhoea as compared to horses with no diarrhoea. Fusobacteria are also higher in the gut microbiota of obese horses, i.e. those with a higher than 3 ‘cresty’ neck score and a Henneke body score greater than 7.
It would seem that obesity and inflammation are linked by a higher count of Fusobacteria whilst the over-eating grass starch event causes a rise in bad bacteria creating an environment of oxidative stress which allows the already present Fusobacteria to increase and fan the flames of an existing inflammatory situation.
According to a leading laminitis expert Dr Hood the worse type of laminitis follows an episode of colitis but the symptoms in the feet don’t start until the diarrhoea has stopped and are caused by the symptoms of shock, often made worse by treatment with intravenous fluids. ‘Hooves affected by colitis laminitis take months if not years to put right’ he states.
Dr Hood concludes that whilst the bowel inflammation causes the horse to be sick, it does not alone cause the horse to have laminitis. What do you think and do you have an experience of laminitis following intravenous fluids to treat colltis?