Sepsis in Foals
One of the most challenging problems faced by equine vets, horse breeders and owners is the detection and management of sepsis in foals. The early, outward symptoms of sepsis in a foal are both subtle and non-specific. Sepsis may arise as a complication of other conditions but if detected early the outcome can be significantly improved through prompt intervention.
Though blood cultures are the definitive test for sepsis, they are prone to false negatives, require specialist equipment and interpretations and take a long time to get a definitive result. The traditional early markers of infection and inflammation, white blood cells (WBC) and fibrinogen also require specialist equipment, laboratory facilities and expert interpretation.
The early signs of infection can be detected using biomarkers of inflammation associated with the innate immune system, a rapidly acting non-specific response giving rise to fever and inflammation among other effects. In the acute phase (which is also responsible for changes to WBC and fibrinogen) serum amyloid A (SAA) levels in the blood rise rapidly (within about 6 hours) up to 1000 fold above the normal level.
SAA has been shown to be a very effective biomarker of acute and systemic inflammatory conditions, including infection. Specific studies on foals have shown that SAA increases significantly in infection, with levels above 100ug/ml (Ref. 1).
In some new born foals, weakly elevated SAA levels can result from birth stresses or from transfer in colostrum. Such raised SAA levels (which are much lower than those expected in a systemic infection or sepsis) are natural and fall to normal levels within days.
There have been some conflicting reports regarding SAA levels associated with R. equi infection (probably related to different detection methodologies), however in a study involving 14 foals EquiChek™-SAA showed elevated SAA levels in R.Equi infected foals confirmed by traditional measures.
EquiChek™-SAA is a rapid test that provides immediate results on the inflammatory status of a foal. The result is semi-quantitative, foals with a significant inflammatory condition can be easily identified using just a drop of blood applied directly to the test device. Results are available in minutes, beside the foal. In conjunction with other clinical information, the SAA result is an aid to assessing the health status of the foal and can be used to help guide therapeutic intervention.
- Stoneham et al Equine Vet J.2001 Nov; 33(6):599-603