• 19 May 2017

Gastrointestinal Tract Health in the Foal - Emma Hardy, PhD

For professional breeders, keeping newborn foals healthy may be the most significant aspect of reducing mortality and increasing the overall value of their breeding stock to reach the sales.

 

The health of the animal is served by the immune system. Establishing and maintaining immune health is critical to the breeder’s success.

The role of the Gastrointestinal tract for immunity

The neonatal foal faces numerous gastrointestinal (GI) challenges particularly within the first few months of life. As soon as the foal is born its GI tract begins to undergo a series of microbial, physiological and physical changes. Perhaps the most crucial is the passive transfer of maternally derived immunoglobulins (predominantly IgG) to the newborn foal. This should occur within the first 1-8 hours after parturition via the mare’s colostrum. Beyond this time window, colostrum IgG concentrations rapidly decrease and ability for the foal to absorb them diminishes.  

Successful transfer helps to protect the foal against infection for the first two to three months when its own immune system becomes fully functional. Unfortunately, some degree of failure of passive transfer (FPT) occurs in around 25% of foals and is diagnosed when foal plasma Immunoglobulin levels are measured at or below 400mg/dl at 12-15 hours post parturition. Supplementary colostrum would likely be administered at this time with the aim of raising plasma immunoglobulin levels to 800mg/dl. Although providing colostrum is a solution for FPT, it is expensive and a less than ideal start for the foal. Where possible, this situation would be best avoided altogether. For broodmares with a history of poor IgG levels, specific nutritional supplementation towards the end of gestation may prove helpful to ensure a good transfer of immunity.

Specific nutritional supplementation can help raise colostrum IgG levels

In a pilot study (Carter & Pellegrini, unpublished) carried out on three thoroughbred breeding farms in the USA, 26 broodmares were randomly placed into two groups. The experimental group received SUCCEED® Digestive Conditioning Program (DCP) 90 days prior to foaling, whilst the second group served as a control. SUCCEED DCP is a polar lipid based supplement which although primarily used to support the health and functioning of the GI tract, also has immunomodulatory properties. Adequate levels of IgG are accepted as between 4000 – 6000 mg/dl colostrum. The broodmares receiving SUCCEED reported a 97% higher IgG concentration in the colostrum (ave. 14038 mg/dl) when compared to the control group (ave. 7078 mg/dl).

Providing additional supplementation towards the end of gestation, aids the health and functioning of the GI tract as well as supporting colostrum IgG levels. This can be highly advantageous for the mare and ultimately, the foal during what is a very nutritionally and physically stressful period. 

EGUS and diarrhoea in foals

During the first two weeks of life, the epithelial layers of the foal’s stomach develop a protective mucus layer over the glandular region. Despite these natural defenses to gastric acid, the prevalence of gastric lesions has been reported to be as high as 60% (Sanchez et al. 1998). Whilst definitive causes are still in question, gastric pH in foals has been reported as being more acidic than in older foals (Baker & Gerring, 1993). It has also been shown that even a small break of 20 minutes between suckling can promote a spike in gastric acid acidity (Sanchez et al. 1998).

Another common GI tract issue for foals is diarrhoea, and studies indicate that up to 80% of foals up to six months of age will experience one or more episodes (Netherwood et al. 1996). Some studies have associated diarrhoea in foals with EGUS possibly inferring hindgut disturbance (Murray 1999, Stoneham, 1996). Acid suppression in adult horses has been associated with an increase in hindgut inflammation (Bedding & Pellegrini, unpublished), so perhaps acid suppressing treatment of EGUS in foals may be responsible for some bouts of diarrhoea.

Fortunately, most diarrhoea is self-limiting and caused by normal developmental changes in the intestinal microflora. However, viral, bacterial or parasitic challenges can also cause diarrhoea and, if suspected, requires further investigation. Rotavirus, salmonellosis, clostridium difficile, clostridium perfringins and lawsonia intracellularis are characterised by systemic illness which can be contagious, severe and even fatal.

Early diagnosis is crucial for rapid recovery

 

When a GI tract problem arises, early detection is key. By establishing the existence and location of an issue, an effective treatment plan can be implemented, rapid recovery more likely achieved and any long-term effects minimised. Screening for occult Albumin and Haemoglobin in a faecal sample, using the Succeed FBT, is a simple, quick and non-invasive first step in the diagnostic process, and may help to decide the next steps of diagnosis or treatment. Further, by broadening our understanding of gastrointestinal disease the focus can be placed on maintaining health and perhaps negating the use prophylactic treatments such as omeprazole in asymptomatic high-risk foals.