Springtime is here with us again, and with it comes the arrival of new life on the farm. Foals are born from August right through spring to summer and in some cases even in autumn.
Most foals will endure at least one bout of diarrhoea during their early lives, and for many the diarrhoea will be restricted to a period approximately a week after birth, colloquially know as ‘foal heat scours’. For a few, the diarrhoea will be severe and require intensive treatment, and unfortunately for some, it will be fatal.
The causes of foal diarrhoea can be divided into two major categories: infectious and non-infectious. This article deals with the non-infectious causes, while in the next issue we will deal with the infectious causes. In this article, when we refer to foals, we are talking about horses aged from 1 day old to 6 months of age.
Diarrhoea can vary in presentation from pasty faeces, seen caked around the anus and surrounding areas, to a bloody watery explosion of faecal water that covers the surrounding environment and renders the foal extremely ill in a short time. It is important to identify which cases require veterinary intervention and which cases the owner can monitor without a risk to the foal’s life.
Foal Heat Diarrhoea (FHD) or scours occurs in most foals and is thought to represent a normal physiological change in the foal’s gut. It can occur from 4-14 days of age and often coincides with the mare’s first oestrous cycle after she foals, which is why it is often referred to as FHD. It is unrelated to the mare’s hormonal levels or changes in her milk and is even seen to occur in orphan foals and foals on artificial diets that have no interaction with the mare. FHD is a self-limiting diarrhoea, meaning that after a short period the diarrhoea resolves without any treatment required. It is important to carefully observe the foal during this time to ensure it remains bright and alert and maintains good hydration. Washing the perineum and applying petroleum jelly to this area is beneficial to help prevent scalding of the area, as the faeces can burn the sensitive skin when it is not removed. The pasty faeces should resolve in 3-5 days and veterinary attention should be sought if this does not occur, as FHD can predispose the foal to other causes of more severe and prolonged diarrhoea.
Nutritional Diarrhoeas are those related to feeding and the type of feed ingested.
1. Foals that engorge themselves when nursing can get diarrhoea because an excessive intake of milk can overwhelm the normal digestive processes. This occurs when the excess milk spills into the lower intestines and allows bacteria to ferment the milk sugars. This can be seen in foals that have been temporarily separated from their mothers and so over-engorge themselves with milk when reintroduced to the mare. In mares that produce large quantities of milk (heavy milkers) foals can be easily overfed, as greater quantities of milk are released from the udder as the foal starts to drink. Regulating the milk intake can help resolve these cases. In mares that produce too much milk, gently stripping some of the contents of the udder can reduce how much the foal drinks in one nursing.
2. Artificial diets, if introduced too quickly, can overwhelm the intestinal tract and stop the normal gut flora and enzymes from digesting the food, allowing unwanted bacteria access to undigested sugars. Any change in diet should be introduced slowly to allow the gut to adapt and reduce the risk of this happening.
3. Lactose intolerance is rare as a primary cause of diarrhoea, however, it can occur secondarily to damage to the intestinal wall. An example of this might be a foal that has lost the lining cells of the gut from a viral infection. The intestinal wall will temporarily lack the cells which produce the enzymes to digest the lactate, allowing it to flow into the lower intestines for the bacteria to ferment.