New research shows that the bacterial population of the foal's digestive tract undergoes major changes within the first two weeks of life. This change seems to be directly responsible for the "foal heat" diarrhoea that is often seen in young foals.The work, carried out at the University of Veterinary Medicine, Vienna and the Graf Lehndorff Institute for Equine Science, Neustadt, Germany, found that the onset of diarrhoea was unrelated to the mare returning to oestrus after giving birth.
Horse-breeders expect most newborn foals to suffer from diarrhoea. Many methods have been suggested to avoid the problem, including supplementing the mothers’ diets with ß-carotene, which is known to be helpful in preventing diarrhoea in young calves. However, Juliane Kuhl in the group of Christine Aurich at the University of Veterinary Medicine, Vienna has now shown that this food supplement has no real effect on the incidence of diarrhoea in foals. Kuhl, Aurich and their collaborators examined the bacteria in the faeces of foals and their mothers, as well as the measuring the levels of antibodies (γ-globulins) in the animals’ blood. They found little change over time in the nature of bacteria in the mothers’ faeces, although they did observe dramatic differences in the bacteria in the foals’ faeces. Foals are born with very low amounts of bacteria in their intestines but are colonized by E. coli within the first day of their lives. In contrast, the number of foals with Enterococcus remains low until about ten days following birth, after which these bacteria can be detected in most animals. Other bacteria such as Streptococcus and Staphylococcus arrive between two and four weeks after birth, by which time the foals’ intestinal flora is essentially indistinguishable from that of their mothers. Interestingly, the researchers found that the changes in the bacterial flora closely parallel the development of diarrhoea. They also found that foals with low γ-globulin levels did not develop diarrhoea more often than those with much higher levels. So, the incidence of diarrhoea cannot be related to a weakened immune system. Kuhl is careful to note that “we have not yet shown that diarrhoea results directly from the switch in intestinal bacteria, although our data make it seem very likely that this is the case.”The implication is that the horse is essentially predisposed to develop diarrhoea at a very young age. As the condition clears up fairly quickly without the need for antibiotic treatment, food withdrawal or food supplements such as ß-carotene, breeders should simply accept that many of their animals will suffer from the condition. Read more at equinescienceupdate.com