Use of the Accusport semi-automated analyser to determine blood lactate as an aid in the clinical assessment of horses with colic

INTRODUCTION Diagnostic methods that evaluate the morphological and functional status of the gastrointestinal tract and the animal’s cardiovascular status are most useful in the initial assessment of equine colic cases. A lethal outcome in a colic case is primarily a result of acute circulatory failure and shock following intestinal ischaemia. Blood lactate concentration (BL) increases during shock mainly due to poor tissue perfusion and anaerobic glycolysis. While BL provides a sensitive biochemical indicator of peripheral tissue perfusion (reflecting both the severity of disease and its prognosis), the best prognostic predictors of altered cardiovascular status are: degree of mental depression, heart rate (HR), oral mucosal colour, capillary refill time (CRT), jugular filling rate, arterial blood pressure, packed cell volume, anion gap and blood urea nitrogen concentration. In general, field cases of colic are successfully managed medically. A smaller percentage (reportedly <10 % of cases) require swift surgical intervention to correct an obstructive lesion. Clinical signs reflect the severity of disease in most cases. The diagnostic and prognostic value of any clinical finding is, however, dependent on the examiner’s skills, experience and interpretation. Appropriate and objective clinicopathological data can be used to enhance the objectivity of the prognosis and diagnosis. Evaluation of clinicopathological data necessitates access to laboratory facilities, which is subject to practical constraints. There are often limitations with respect to both the availability and economics of the various laboratory tests. Colic cases by their nature and aetiologies require rapid evaluat ion, prognosis and therapeutic management. This is particularly relevant in identifying potentially successful surgical cases. A hand-held lactate meter, Accusport (Boehringer Mannheim GmbH) has recently become available and provides a rapid, inexpensive drychemical-based determination of BL concentration within 60 seconds. The lactate concentration is determined from plasma by photometry after whole blood placed on a dry chemistry strip enters a measuring chamber. The Accusport was designed to measure BL in human athletes, but several recent studies have evaluated its application in BL determination of equine athletes. The concentration of whole blood lactate is calculated by a conversion formula valid for humans. These conversion formulae appear to be applicable to the horse. In horses, unlike humans, the correlation between plasma and whole blood lactate is narrow, with increasing plasma to whole blood ratio as blood lactate rises. The ratio change is too small to markedly affect blood lactate as determined by either wet or dry chemistry methods. While a number of studies have discussed the value of BL determination in equine colic cases, no studies have reported the use of the Accusport in the assessment of the colic horse. The instrument’s potential clinical use is dependent on the provision of accurate data in the determination of BL within the expected range observed in horses with colic. This trial evaluated the Accusport’s ability to determine BL as an adjunct to the clinical assessment of equine colic cases. Determinations of BL by the Accusport were compared with an enzymatic method. In addition, these data were compared with those determined using a Nova Stat Profile Plus 7L semiautomated analyser (NOVA Biomedical).