Nutritional management of small intestinal malabsorption syndrome in nine horses

C

Quantification of left ventricular longitudinal strain, strain rate, velocity and displacement in healthy horses by 2-dimensional speckle tracking

Background: The quantification of equine left ventricular (LV) function is generally limited to short-axis M-mode measurements. However, LV deformation is 3-dimensional (3D) and consists of longitudinal shortening, circumferential shortening, and radial thickening. In human medicine, longitudinal motion is the best marker of subtle myocardial dysfunction. Objectives: To evaluate the feasibility and reliability of 2-dimensional speckle tracking (2DST) for quantifying equine LV longitudinal function. Animals: Ten healthy untrained trotter horses; 9.6 +/- 4.4 years; 509 +/- 58 kg. Methods : Prospective study. Repeated echocardiographic examinations were performed by 2 observers from a modified 4-chamber view. Global, segmental, and averaged peak values and timing of longitudinal strain (SL), strain rate (SrL), velocity (VL), and displacement (DL) were measured in 4 LV wall segments. The inter- and intraobserver within- and between-day variability was assessed by calculating the coefficients of variation for repeated measurements. Results: 2DST analysis was feasible in each exam. The variability of peak systolic values and peak timing was low to moderate, whereas peak diastolic values showed a higher variability. Significant segmental differences were demonstrated. DL and VL presented a prominent base-to-midwall gradient. SL and SrL values were similar in all segments except the basal septal segment, which showed a significantly lower peak SL occurring about 60 ms later compared with the other segments. Conclusions and Clinical Importance 2DST is a reliable technique for measuring systolic LV longitudinal motion in healthy horses. This study provides preliminary reference values, which can be used when evaluating the technique in a clinical setting

Cardiac troponin I as compared to troponin T for the detection of myocardial damage in horses

Background: Different cardiac troponin I (cTnI) assays give different results. Only 1 manufacturer has marketed troponin T (cTnT) assays. Therefore, cTnT often is preferred for detection of myocardial infarction in human patients. Studies of cTnT in horses are limited. Objectives: To compare a cTnI and a high-sensitive cTnT assay (hs-cTnT) in horses. Animals: Cardiac troponin I and cTnT were determined in 35 healthy horses (group 1), 23 horses suspected to have primary myocardial damage (group 2a), and 41 horses with secondary myocardial damage caused by structural heart disease (group 2b). Methods: All cTnI samples were analyzed at laboratory A (limit of detection [LOD]: 0.03 ng/mL), whereas cTnT samples were analyzed at 2 laboratories with the same hs-cTnT assay (laboratory B, LOD: 10.0 pg/mL; laboratory C, LOD: 4.0 pg/mL). Results: The median cTnI concentration in group 2a (0.90 ng/mL; range, 0.03–58.27 ng/mL) was significantly higher (P < .001) than in group 1 (0.03 ng/mL; range, 0.03–0.09 ng/mL) or group 2b (0.05 ng/mL; range, 0.03–30.92 ng/mL), and the optimal cut-off for detection of primary myocardial damage was 0.095 ng/mL (sensitivity: 90.5%, specificity: 100%). Using an LOD of 10.0 pg/mL for all cTnT samples, a cut-off value of 10.5 pg/mL was found, but sensitivity was low (42.9%). When only samples analyzed at laboratory C (n = 58) were included, a cut-off of 6.6 pg/mL was found (sensitivity: 81%, specificity: 100%). Conclusions and Clinical Importance: Despite large quantitative differences, cTnI and cTnT are both useful for detection of myocardial damage in horses

Electrocardiography in horses, part 2: how to read the equine ECG

The equine practitioner is faced with a wide variety of dysrhythmias, of which some are physiological. The recording of an exercise electrocardiogram (ECG) can help distinguish between physiological and pathological dysrhythmias, underlining the importance of exercise recordings. The evaluation of an ECG recording should be performed in a highly methodical manner in order to avoid errors. Each P wave should be followed by a QRS complex, and each QRS complex should be preceded by a P wave. The classification of dysrhythmias according to their origin helps to understand the associated changes on the ECG. In this respect, sinoatrial nodal (SA nodal), atrial myocardial, atrioventricular nodal (AV nodal) and ventricular myocardial dysrhythmias can be distinguished. Artefacts on the ECG can lead to misinterpretations. Recording an ECG of good quality is a prerequisite to prevent misinterpretations, but artefacts are almost impossible to avoid when recording during exercise. Changes in P or T waves during exercise also often lead to misinterpretations, however they have no clinical significance

Electrocardiography in horses, part 1: how to make a good recording

Upon auscultation, cardiac dysrhythmias can be suspected, but electrocardiography is the ultimate diagnostic tool. Electrocardiogram (ECG) recording used to be reserved to specialized centers, but nowadays relatively cheap and small recorders are available to the practitioner in the field. ECGs can therefore be recorded ambulatory and during prolonged periods at rest or even during exercise. The know-how of a good quality recording is mandatory for a correct diagnosis. The basic equipment consists of electrodes, a recorder and a way to display the trace. Self-adhesive electrodes should be used, and positioned along the mean electrical axis of the heart. Small recording devices offer the advantage of allowing recordings during exercise. As the electrical impulse spreads through the heart, the ECG trace shows successively a P wave, a QRS complex and a T wave. T-a waves are not always clearly visible in horses. The positioning of the electrodes may differ for ambulatory, exercise or long-term resting recordings. However, as long as the electrodes are positioned along the mean electrical axis, their exact position is not of crucial importance

The use of cardiac biomarkers in veterinary medicine: the equine perspective

In human medicine, cardiac biomarkers, such as natriuretic peptides and troponins, are routinely used for the diagnosis, prognosis and monitoring of heart diseases. Similarly, these biomarkers are determined in small animals to differentiate non-cardiac from cardiac diseases. Knowledge about these biomarkers in horses is limited and requires further investigation. The first equine studies about atrial natriuretic peptide (ANP) and N-terminal ANP (NT-proANP) are promising, and show a clear correlation with atrial dimension size. Equine brain natriuretic peptides assays are still unavailable. The troponins, in particular troponin I, have been more extensively studied in horses, and their use for the diagnosis of myocardial damage has been fully demonstrated. They have replaced the less specific lactate dehydrogenase and creatine kinase isoenzymes, which makes the use of the last mentioned no longer legitimate. A final possible equine biomarker is aldosterone. Reference values in horses have been established. However, in only one study, a correlation between aldosterone and cardiac disease has been reported