EQUINE VETERINARY EDUCATION / AE / JANUARY 2017


5


Highlights of recent clinically relevant papers


Oral. sugar test in nonfasted ponies? This study by Edd Knowles and colleagues in the UK compared the oral sugar test (OST) for diagnosis of insulin dysregulation in fasted and nonfasted ponies. Ten native pony mares were subjected to four OSTs, two


fasted overnight and two fed (left out at pasture). Blood samples for measurement of serum insulin concentration were taken before oral administration of 0.15 ml/kg bwt of Karo syrup (corn oil) and at 30, 60, 75, 90 and 120 min. Insulin concentrations were measured using a radioimmunoassay. There were significant differences between the insulin


response under fasting and fed conditions. Fasting exacerbated the insulin response to sugar, and fasting and fed tests cannot be used interchangeably. However, tests under both fasting and fed conditions had similar reliability. Additionally, although insulin values tended to differ fairly widely at the same time point within the same individual, and hence repeatability between individual OSTs was poor, the results of fasted and fed tests were similar in the context of dichotomous interpretation, i.e. whether ponies were defined as having insulin dysregulation or not. Within this context there was good agreement between fasted and fed results within individual ponies. Therefore a nonfasted test will still be likely to diagnose whether insulin dysregulation is present, but repeating the test to monitor changes in insulin concentrations in an individual may not be very reliable. Peak insulin concentrations were recorded most commonly at 30 min in both fasted and fed conditions, with the majority of the rest occurring at 60 min. The authors concluded that the test is still likely to identify


insulin regulation/dysregulation if fasting before an OST is not possible. The optimal window for sampling is up to 60 min.


Equine neuroborreliosis


In this study Laura Johnstone and colleagues in the USA provide a description of clinical signs, diagnostic and pathological findings of horses with neuroborreliosis (Lyme disease). A retrospective review of medical records was performed


with inclusion criteria requiring possible exposure to Borrelia burgdorferi and histological findings consistent with previous reports of neuroborreliosis (NB) without evidence of other disease. Sixteen horses were identified, 12 of which had additional evidence of NB. Clinical signs were variable including muscle atrophy or weight loss (12), cranial nerve deficits (11), ataxia (10), changes in behaviour (9), dysphagia (7), fasciculations (6), neck stiffness (6), episodic respiratory distress (5), uveitis (5), fever (2), joint effusion (2), and cardiac arrhythmias (1). Serological analysis was positive for B. burgdorferi infection in 6/13 cases tested. Cerebrospinal fluid (CSF) abnormalities were present in 8/13 cases, including xanthochromia (4/13), increased total protein (5/13; median: 91 mg/dL), and a neutrophilic (6/13) or lymphocytic (2/13) pleocytosis (median: 25 nucleated cells/lL). PCR on CSF for B. burgdorferi was negative in the seven cases that were tested. Diagnosis of equine NB is challenging owing to variable


clinical presentation and lack of sensitive and specific diagnostic tests. Negative serology and normal CSF analysis do not exclude the diagnosis of NB.


Equine pain scales


This study by Machteld VanDierendonck and Johannes van Loon validates two pain scales, the Equine Utrecht University Scale for Composite Pain Assessment (EQUUS-COMPASS) and the Equine Utrecht University Scale for Facial Assessment of Pain (EQUUS-FAP), in horses with acute colic. A follow-up cohort study of 46 adult horses (23 with acute


colic and 23 healthy control horses) was performed for validation and refinement of the constructed scales. Both pain scales showed statistically significant differences between horses with colic and healthy control horses, and between horses with colic that could be treated conservatively and those that required surgical treatment or were euthanased. Sensitivity and specificity were good for both EQUUS-COMPASS (87% and 71%, respectively) and EQUUS-FAP (77% and 100%, respectively) and were not substantially influenced by applying weighting factors to the individual parameters.


Multiple organ dysfunction syndrome


The aims of this study by Erin McConachie and colleagues in the USA were to develop criteria for a multiple organ dysfunction syndrome (MODS) score for horses with acute surgical colic (MODS SGI) and evaluate the association with 6-month survival, also to compare the MODS SGI score with a MODS score extrapolated from criteria used in people (MODS EQ).


Prospectively, a MODS SGI score was developed based


on organ-specific criteria established from a literature review, data collection, and clinical judgement. Data for scoring each horse (62 adult horses that required exploratory laparotomy for colic) were collected on Days 1 and 2 post- operatively. Twelve healthy adult horses undergoing elective surgical procedures established the reference range of some variables. Horses were scored retrospectively using both scoring criteria. The prognostic performance of the MODS SGI score and its overall performance compared with the MODS EQ score were assessed with receiver operating characteristic (ROC) curve analysis. The MODS SGI score had excellent performance for


predicting 6-month survival with an area under the ROC curve (AUC) of 0.95. The AUC for the MODS SGI score was significantly higher than the MODS EQ (AUC: 0.76).


Band cells and toxic neutrophils in horses with acute diseases


In this study J.L. Lambert and colleagues in Canada evaluated the association of band cells and toxic neutrophils with systemic inflammatory response syndrome (SIRS) and outcome in horses. The 105 adult horses included in this study all had a CBC


and a blood smear collected at admission on an emergency basis to a private primary referral practice. The detection of band neutrophils on admission was


associated with the SIRS status of the horse and with poor outcome. Similarly, the presence of a neutrophil toxic grade higher than 3 was associated with SIRS and death. The


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