[Helminth control in the adult horse: the need for a re-orientation]. / Helminthenmanagement beim adulten Pferd: Notwendigkeit einer Neuorientierung.

The epidemiological situation of strongyle infections in adult horses in Switzerland is characterized by a strong dominance of small strongyles (Cyathostominae) and an overall low level of egg shedding in the faeces. The prevailing attitude towards anthelmintic therapy considers neither husbandry conditions nor pasture hygiene measures. Instead, calendar-based routine medication, comprising usually 3 to 4 annual treatments, is the typical strategy. Such an approach, however, often results in an excessive administration of anthelmintics. With respect to the continuous spread of drug resistant cyathostomins a change of strategy seems inevitable. A consensus has been agreed on between equine parasitologists and clinicians of the Vetsuisse Faculty in Zurich and Berne to focus on the concept of a selective control approach, based on individual faecal egg counts as the central element. It is now recommended that clinically healthy horses (> 4 y) are treated only when their strongyle egg count is equal to or higher than 200 eggs per gram of faeces. A regular analysis of the strongyle population based on larval cultures, the control of drug efficacy, and quarantine measures for incoming horses are mandatory components of the concept. Recent experiences in several pilot farms have indicated that only 4 % of the McMaster analyses resulted in a deworming treatment. For horses that did not receive any nematicidal anthelmintic during the current season, a "safety" treatment is recommended at the end of the grazing period.

En Suisse, la situation épidémiologique des infestations des chevaux adultes par les strongylidés est caractérisée par une nette dominance des petits strongles (Cyathostominae) et par un faible niveau d'excrétion des œufs de parasites dans les selles. Cars les conditions de détention des chevaux et les mesures relatives à l'hygiène des pâtures ne sont que rarement prises en compte dans la planification des mesures de contrôle des parasitoses, il en résulte un schéma de traitement de routine basé sur 3 à 4 traitements par année, ce qui représente un usage d'anthelminthiques souvent supérieur à la nécessité. Vu le développement continu de populations de cyatostomes résistants aux anthelminthiques, un changement de stratégie dans le contrôle des helminthes est nécessaire. Le contrôle sélectif propagé par les parasitologues et les cliniciens des deux sites de la faculté Vetsuisse propose de seulement traiter les chevaux sains adultes (> de 4 ans) si l'excrétion des œufs de strongles dépasse 200 œufs par gramme de selles. Une différentiation régulière des populations de strongles, le contrôle de l'efficacité des anthelminthiques et des mesures de quarantaines chez les nouveaux venus sont des composants indispensables de ce concept. Les expériences faites jusqu'à présent avec cette stratégie dans plusieurs exploitations-pilotes montrent que seulement 4 % des analyses coprologiques sont suivies par une application d'anthelminthiques. Pour les chevaux qui n'ont pas été vermifugés pendant toute la saison, un traitement de sécurité à la fin de la saison de pâturage est recommandé.

EcPV2 DNA in equine papillomas and in situ and invasive squamous cell carcinomas supports papillomavirus etiology.

Equine penile papillomas, in situ carcinomas, and invasive carcinomas are hypothesized to belong to a continuum of papillomavirus-induced diseases. The former ones clinically present as small grey papules, while the latter 2 lesions are more hyperplasic or alternatively ulcerated. To test the hypothesis that these lesions are papillomavirus-induced, samples of 24 horses with characteristic clinical and histologic findings of penile papillomas or in situ or invasive squamous cell carcinomas were collected. As controls, 11 horses with various lesions--namely, Balanoposthitis (6 cases), melanoma (3 cases), follicular cyst (1 case), and amyloidosis (1 case)--were included. DNA was extracted and polymerase chain reaction applied to amplify papillomavirus DNA. The respective primers were designed to amplify DNA of the recently discovered equine papillomavirus EcPV2. All tested papilloma and squamous cell carcinoma samples were found to contain DNA of either of 2 previously published EcPV2 variants. Among the other samples 6 of 11 were found to contain EcPV2 DNA. To further support the findings and to determine where the papillomavirus DNA was located within the lesions, an in situ hybridization for the detection of EcPV2 DNA was established. The samples tested by this technique were found to clearly contain papillomavirus nucleic acid concentrated in the nucleus of the koilocytes. The findings of this study support previous data and the hypothesis that papillomaviruses induce the described penile lesions in horses.

Diagnostic value of two-dimensional echocardiographic measurements of the pulmonary artery diameter and the pulmonary artery distensibility index to detect pulmonary hypertension in horses.

INTRODUCTION/OBJECTIVES: Echocardiographic diagnosis of pulmonary hypertension (PH) in horses is usually based on Doppler interrogation of tricuspid (TR) or pulmonic regurgitation (PR). This study aimed at investigating two-dimensional echocardiographic (2DE) variables, including pulmonary artery diameter (PAD) and pulmonary artery distensibility index (PADI), to diagnose PH. ANIMALS, MATERIALS AND METHODS: 41 healthy horses; 82 horses with TR or PR and normal intracardiac pressure gradients; and 35 horses with TR or PR velocities indicating PH. The 2DE variables were compared between groups, cut-offs for the diagnosis of PH were determined, and conditional inference trees served to identify the variable best predicting PH in the absence of TR or PR. RESULTS: Horses with PH had larger end-diastolic cross-sectional (short-axis) PAD (PADed-sx) (5.8 ± 1.0 cm; mean ± SD) and smaller PADI[/PADps] (15.4 ± 7.7%) than healthy horses (5.0 ± 0.6 cm, P<0.0001; 20.5 ± 4.4%, P<0.001) and horses with TR or PR but no PH (5.3 ± 0.6 cm, P=0.003; 18.8 ± 4.2%, P=0.005). PADed-sx predicted PH with sensitivity (Se) = 36% and specificity (Sp) = 94% (cut-off 6.0 cm, AUC = 0.668, P=0.002), while PADI[/PADps] predicted PH with Se = 43% and Sp = 92% (cut-off 13.7%, AUC = 0.662, P=0.004). In the absence of TR, PADed-sx and the end-diastolic long-axis aortic diameter-to-PADed-sx ratio (AoDed-lx/PADed-sx) were most suitable to diagnose PH. CONCLUSION: Pulmonary artery crosssectional (short-axis) diameter at end-diastole measured in a right-parasternal long axis view of the left ventricular outflow tract and Pulmonary artery distensibility index were moderately specific but not very sensitive to diagnosing PH. Nonetheless, they may be used as complementary indices suggesting PH in the absence of TR or PR.

Echocardiography in Saanen-goats: Normal findings, reference intervals in awake goats, and the effect of general anesthesia.

Echocardiographic assessment of cardiac structures, dimensions, and mechanical function in goats is poorly documented. The goal of this study was to describe normal findings, establish normal values for two-dimensional (2DE) and M-mode (MME) echocardiography, and investigate the influence of general anaesthesia. Standardized 2DE and MME recordings were obtained on 22 healthy female Saanen goats (3.7 ± 1.1 years [mean ± SD], 60.2 ± 10.6 kg) awake (standing) and during isoflurane anesthesia (sternal recumbency). Cardiac dimensions and function were assessed and compared between treatments (awake vs. anaesthetized). Color Doppler imaging and saline contrast studies served to assess abnormal blood flow patterns. Post mortem examination was performed in a subset of 12 goats. Transthoracic echocardiography was feasible in all goats. Indices of LV systolic function proved to be significantly increased during general anesthesia. The membranous and occasionally echolucent appearance of the oval fossa suggested abnormal interatrial communication in 9 goats. Color Doppler imaging and saline contrast studies proved to be inaccurate to detect interatrial shunting of blood. Post mortem examination confirmed small persistent foramen ovale in only 3 out of 7 goats, in which it had been suspected on echocardiography.

Quantification of left atrial contractile function using two-dimensional speckle tracking echocardiography in horses after conversion of atrial fibrillation to sinus rhythm.

INTRODUCTION/OBJECTIVES: In horses, persistent atrial dysfunction is a prognostic indicator of recurrence of atrial fibrillation (AF). The objective of this study was to quantify left atrial (LA) contractile function in Warmblood horses after successful cardioversion of AF to sinus rhythm, using standard two-dimensional echocardiography (2DE) and two-dimensional speckle tracking (2DST) analyses, and to provide proof-of-concept for use of 2DST to detect LA contractile dysfunction in horses. ANIMALS, MATERIALS, AND METHODS: Nineteen Warmblood horses with AF and successful transvenous electrical cardioversion (TVEC) or medical cardioversion using quinidine sulfate (QS) were included. Echocardiography was performed at 24 hr, 72 hr, and 1-6 months after cardioversion. Conventional 2DE-derived indices of LA size and function and global longitudinal strain (SL) and longitudinal strain rate (SRL) during LA contractile function were measured to detect differences in LA size and function over time and between treatment modalities. The association between 2DE-derived indices and global SL and SRL, respectively, and the agreement of the variables to detect LA dysfunction were assessed. RESULTS: Global SL and SRL, as well as active LA fractional area change (FAC) identified cases with LA dysfunction after TVEC and QS cardioversion and proved useful to demonstrate LA functional recovery over time. Agreement between active LA FAC and SL and SRL, respectively, to diagnose atrial dysfunction was substantial to fair at 24 hr after cardioversion and decreased with time. CONCLUSION: This study shows that 2DST is useful to quantify LA contractile dysfunction in horses after cardioversion of AF.

Balloon valvuloplasty of valvular pulmonary stenosis in a neonatal foal.

In a 1-day old filly with a loud heart murmur, transthoracic echocardiography revealed right ventricular hypertrophy associated with severe pulmonary valvular stenosis and a transvalvular pressure gradient (between right ventricle and pulmonary artery) of 125 mmHg. Computed tomographic angiography confirmed the finding, with no evidence of other relevant concurrent abnormalities. Balloon valvuloplasty was performed using a single balloon technique. The foal recovered well from anaesthesia. Following the procedure, the right ventricle-pulmonary artery transvalvular gradient decreased to 38 mmHg. At follow up examinations after 1 month, 1 year and 2 years, the filly showed normal exercise capacity and echocardiography confirmed the persistent substantial improvement in the transvalvular outflow gradient.

Quantitative analysis of stress echocardiograms in healthy horses with 2-dimensional (2D) echocardiography, anatomical M-mode, tissue Doppler imaging, and 2D speckle tracking.

BACKGROUND: Stress echocardiography is used to diagnose myocardial dysfunction in horses, but current methods are not well standardized. The influence of heart rate (HR) on measurements is largely unknown. OBJECTIVES: To investigate the use of 2-dimensional echocardiography (2DE), anatomical M-mode (AMM), tissue Doppler imaging (TDI), and 2D speckle tracking (2DST) at rest and after exercise for quantification of regional and global left-ventricular (LV) function. ANIMALS: Five athletic Warmblood horses; 11.6+/-3.6 years; 529+/-48 kg. METHODS: Prospective study. Three separate echocardiographic examinations were performed before (baseline) and over 5 minutes after treadmill exercise with 2DE (1st, short-axis view; 2nd, long-axis view) and pulsed-wave TDI (3rd examination). Offline analyses were performed at baseline and after exercise at HR 120, 110, 100, 90, and 80 minute(-1). Global and segmental measurements were compared by analysis of variance. RESULTS: Quantitative analyses of stress echocardiograms were feasible in all horses. None of the AMM indices changed significantly after exercise. Stroke volume and ejection fraction by 2DE and strain by 2DST decreased, whereas strain rate by 2DST increased significantly at HR>100 minute(-1). TDI analyses were technically difficult and provided little additional information. CONCLUSIONS AND CLINICAL IMPORTANCE: Volumetric indices by 2DE and strain and strain rate by 2DST are applicable for quantitative assessment of stress echocardiograms. In healthy horses, they are significantly altered at a HR>100 minute(-1) and need to be evaluated in view of the instantaneous HR. Further investigations are needed to define the clinical value of stress echocardiography in horses with cardiac disease.

Quantification of left atrial wall motion in healthy horses using two-dimensional speckle tracking.

INTRODUCTION: The mechanical function of the left atrium (LA) plays a pivotal role in modulation of left ventricular filling. Assessment of LA function might be a clinically useful prognostic tool for horses with mitral regurgitation or atrial fibrillation. However, the most accurate, reliable, and clinically useful methods to assess LA myocardial function are yet to be determined. The objective of this study was to describe the methods for quantification of LA wall motion using two-dimensional speckle tracking (2DST) echocardiography in healthy Warmblood horses to quantify measurement variability, to calculate reference intervals for 2DST variables, and to investigate their relationship to sex, age, body weight, and heart rate. ANIMALS, MATERIALS, AND METHODS: Twenty-six healthy Warmblood horses were included. 2DST analyses of LA wall motion were performed on digitally stored cine-loop recordings of a standardized right-parasternal four-chamber view focusing on the LA. Longitudinal strain, longitudinal strain rate, and time to peak LA contraction were measured to characterize LA contractile, reservoir, and conduit function. Intraobserver and interobserver measurement variability was quantified, and reference intervals were calculated. RESULTS: The coefficient of variation for intraobserver and interobserver measurement variability ranged between 2.0-11.1% and 5.1-15.4%, respectively, for global strain, strain rate, and time to peak LA contraction. Reference intervals for healthy Warmblood horses were reported. CONCLUSION: This study shows that 2DST is a feasible and reliable method to quantify LA wall motion throughout the cardiac cycle in healthy Warmblood horses. Further studies are required to establish the clinical value of 2DST for assessment of LA function.

Methods and reliability of tissue Doppler imaging for assessment of left ventricular radial wall motion in horses.

BACKGROUND: Noninvasive assessment of left ventricular (LV) function is incompletely studied in horses. OBJECTIVES: The goals of this study were to investigate the feasibility, techniques, and reliability of tissue Doppler imaging (TDI) for characterization of LV radial wall motion in healthy horses. ANIMALS: Three Standardbreds, 3 Thoroughbreds; age 8-14 years; body weight 517-606 kg. METHODS: Repeated echocardiographic examinations were performed by 2 observers in unsedated horses using TDI. Test reliability was determined by estimating measurement variability, within-day interobserver variability, and between-day interobserver and intraobserver variability of all echocardiographic variables. Variability was expressed as coefficient of variation (CV) and the absolute value below which the difference between 2 measurements will lie with 95% probability. RESULTS: Assessment of LV radial wall motion by TDI was feasible in all horses. Measurement variabilities were very low (CV < 5%) to low (CV 5-15%) for most variables. Within-day interobserver variability as well as between-day interobserver and intraobserver variabilities were low to moderate (CV 16-25%) for most variables. All pulsed-wave TDI variables of systolic LV function showed very low to low variability, whereas some of the variables of LV diastolic and LA function showed moderate to high (CV > 25%) variability. Pulsed-wave TDI variables appeared more reliable than color TDI variables. CONCLUSIONS AND CLINICAL IMPORTANCE: Measurement of TDI indices of LV function is feasible and reliable in adult Standardbred and Thoroughbred horses. The clinical relevance of LV function assessment by TDI remains to be determined.

Left ventricular radial and circumferential wall motion analysis in horses using strain, strain rate, and displacement by 2D speckle tracking.

BACKGROUND: Noninvasive assessment of left-ventricular (LV) function is clinically relevant, but is incompletely studied in horses. OBJECTIVES: To document the feasibility, describe the techniques, and determine the reliability of 2D speckle tracking (2DST) for characterization of LV radial and circumferential wall motion in horses. ANIMALS: Three Standardbreds, 3 Thoroughbreds; age 8-14 years; body weight 517-606 kg. METHODS: Observational study. Repeated 2-dimensional echocardiographic examinations were performed in unsedated horses by 2 observers and subsequently analyzed by 2DST. Test reliability was determined for segmental and for averaged 2DST indices (including strain, strain rate, displacement, and rotation) by estimating measurement variability, within-day interobserver variability, between-day interobserver variability, and between-day intraobserver variability. Variability was expressed as coefficient of variation (percent) and the absolute value below which the difference between 2 measurements will lie with 95% probability. RESULTS: 2DST analyses were feasible in 16 of 18 echocardiographic studies. The automated tracking was accurate during systole but inaccurate during diastole. Reliability was higher for radial compared to circumferential measurements. For radial strain, radial systolic strain rate, and radial systolic displacement, the test-retest variabilities ranged between 2.4 and 33.1% for segmental and between 4.1 and 16.1% for averaged measurements. CONCLUSIONS AND CLINICAL IMPORTANCE: Systolic radial motion of the LV at the chordal level could be reliably characterized in horses by 2DST. Circumferential measurements were less reliable. Diastolic measurements were invalid because of inaccurate tracking. The clinical value of LV wall motion analysis by 2DST in horses requires further investigation.

Assessment of systolic and diastolic function in clinically healthy horses using ambulatory acoustic cardiography.

BACKGROUND: Assessment of cardiac electromechanical function in horses requires training, experience and specialised equipment and does not allow continuous monitoring over time. OBJECTIVES: The objective of this study was to establish the use of an acoustic ECG monitor (Audicor® ) in healthy horses. It provides noninvasive, examiner-independent, continuous analyses combining ECG and phonocardiography to calculate indices of cardiac mechanical activity and haemodynamics. Device usability was investigated, reference intervals calculated and reproducibility of analyses assessed. STUDY DESIGN: Prospective descriptive study. METHODS: Continuous overnight recordings were obtained in 123 healthy horses. ECG and acoustic cardiography analyses were performed. Electromechanical activating time (EMAT), rate-corrected EMATc, left ventricular systolic time (LVST), rate-corrected LVSTc and intensity and persistence of the third and fourth heart sound (S3, S4) were reported. Associations with age and reproducibility of analyses were assessed. RESULTS: Audicor® recordings of diagnostic quality were obtained in 116 horses, with an artefact-free recording time of 1:08-14:03 h (mean 10:21 h). 44.8% of the horses had atrial premature complexes (up to 0.18% of analysed beats), 4.3% had ventricular premature complexes (up to 0.021% of analysed beats). Reference intervals for acoustic cardiography variables were reported. S3 was significantly more often graded ≥5 (scale 0-10) in younger compared to older horses (P = 0.0036, R2  = 0.072). The between-day coefficient of variation ranged from 2.5 to 7.7% for EMAT, EMATc, LVST and LVSTc. MAIN LIMITATIONS: Audicor® algorithms are based on human databases. Horses were deemed clinically healthy without advanced diagnostics. Some data were lost because of technical difficulties, artefacts and noises. CONCLUSIONS: Overnight Audicor® recordings are feasible in horses. Combining ambulatory ECG and phonocardiography allows noninvasive, continuous assessment of variables representing systolic and diastolic cardiac function. ECG rhythm analyses require over-reading by a specialist, but acoustic cardiography variables are based on automated algorithms independent of examiner input. Further studies are required to establish the clinical value of acoustic cardiography in horses.

Plasma homocysteine concentrations in healthy horses and horses with atrial fibrillation.

INTRODUCTION: Homocysteine (HCY) is an amino acid produced from methionine metabolism. Plasma homocysteine concentrations ([HCY]p) are elevated (>13 µmol/L) in people with atrial fibrillation (AF) and can predict the recurrence of AF after cardioversion. This study aimed to validate a commercially available human HCY assay for use in horses to develop reference intervals for [HCY]p and compare [HCY]p in healthy horses and horses with AF. ANIMALS: Healthy horses (n = 27) and horses with AF (n = 55, 34 of which were cardioverted using transvenous electrical cardioversion). MATERIALS AND METHODS: Blood samples were analysed for HCY using an automated enzyme-cycling assay (Homocysteine Cobas C, Integra, Roche) and creatinine (compensated Jaffe method). Assay linearity and precision were assessed, reference intervals calculated and [HCY]p and creatinine compared between groups. RESULTS: The assay was precise (coefficient of variation 1.6-4.3%, n = 10 repetitions) and provided linear results (r = 0.99 for spiked and natural samples) for a range of [HCY]p. The reference interval for [HCY]p was 1.5-7.8 µmol/L. The plasma concentration of homocysteine was 4.65 ± 1.5 µmol/L (mean ± standard deviation) in healthy horses and 4.65 ± 1.72 µmol/L in horses with AF (p=0.99); [HCY]p was not associated with recurrence of AF (n = 18, p=0.97). A weak, positive correlation between plasma creatinine and [HCY]p was detected (r = 0.295, p=0.008, r2 = 0.11). CONCLUSIONS: This assay allows precise measurement of [HCY]p in horses. Unlike in people, [HCY]p is not increased in horses with AF and cannot predict AF recurrence. This might be due to differences in the underlying pathological mechanisms of AF development in people and horses.

Influence of 2nd-degree AV blocks, ECG recording length, and recording time on heart rate variability analyses in horses.

OBJECTIVES: To assess the influence of 2nd-degree AV blocks (AVB) on RR interval-based heart rate variability (HRV) variables; to investigate the effect of using PP interval time series and of artifact filtering on HRV analyses; to investigate the influence of electrocardiogram (ECG) recording length and time of recording; and to calculate day-to-day variability and reference intervals of HRV variables. ANIMALS: Thirty healthy adult horses. METHODS: RR and PP interval time series were extracted from 10-h Holter ECGs and an automated filter was applied to the RR time series (RRf). Time-domain HRV variables were calculated based on RR, PP, and RRf time series and their relation to the number of AVBs was assessed. Hourly 10- and 60-min segments were extracted to investigate the influence of segment length and recording time on HRV variables. Day-to-day variability and reference intervals of HRV variables were calculated. RESULTS: Variables of short-term HRV were significantly influenced by the number of AVBs when based on RR, but not when based on PP- and RRf time series. PP- and RRf-based HRV variables were in good agreement. The majority of HRV variables were influenced by recording time and ECG segment length. Day-to-day variability of HRV variables was low when based on 10-h ECG recordings but moderate to high when based on 60-min and 10-min recordings. CONCLUSIONS: Second-degree AVBs significantly influence conventional RR-based, but not PP- and RRf-based time-domain HRV variables. However, PP and RRf analyses have limitations and recording length and time of recording must be considered.

Echocardiographic Assessment of Left Ventricular Function in Healthy Horses and in Horses with Heart Disease Using Pulsed-Wave Tissue Doppler Imaging.

BACKGROUND: Assessment of left ventricular (LV) function by tissue Doppler imaging (TDI) is not well established in horses with heart disease. OBJECTIVES: To describe the use of pulsed-wave (PW) TDI for the assessment of LV function, establish reference intervals, investigate effects of mitral regurgitation (MR), aortic regurgitation (AR), and primary myocardial disease (MD), and provide proof of concept for the use of PW TDI in Warmblood horses with heart disease. ANIMALS: Thirty healthy horses, 38 horses with MR, 25 with AR, 8 with MD. METHODS: Echocardiograms were retrospectively analyzed. Reference intervals were calculated. PW TDI indices of healthy horses and horses with MR, AR, and MD were compared by one-way ANOVA and Dunnett's test. RESULTS: A complete set of PW TDI variables could be obtained in 94 of 101 horses. Variables corresponding to isovolumic intervals were most difficult to measure. Valvular regurgitation influenced variables describing isovolumic contraction and ejection. Horses with MD had significantly shortened ETm (-118.5 [-154.1 to -82.9] ms; mean difference [95% CI of difference of means]), increased PEPm /ETm (0.11 [0.05 to 0.17]), prolonged IMPm (0.28 [0.18 to 0.37]), increased S1 (8.9 [5.2 to 12.6] cm/s), and decreased E1 (-2.6 [-4.7 to -0.5] cm/s), Em (-14.2 [-19.9 to -8.5] cm/s), and Em /Am ratio (-1.6 [-2.6 to -0.6]). CONCLUSIONS AND CLINICAL IMPORTANCE: Pulsed-wave TDI might be useful for detection of LV dysfunction in horses with primary MD. The clinical value of TDI in horses with MR and AR remains uncertain.

Validation of a Point-of-Care Quantitative Equine IgG Turbidimetric Immunoassay and Comparison of IgG Concentrations Measured with Radial Immunodiffusion and a Point-of-Care IgG ELISA.

BACKGROUND: Point-of-care (POC) diagnostic tests with good sensitivity and specificity are needed for diagnosing failure of transfer of passive immunity (FTPI) in foals. Turbidimetric immunoassays (TIA) have these characteristics and provide quantitative results. A commercially available TIA-based POC test (POC-TIA) has not been validated in horses. OBJECTIVE: To validate a POC-TIA and compare results of POC-TIA, a POC-ELISA, and radial immunodiffusion (RID). ANIMALS: Heparinized blood samples (n = 127) from 48 hospitalized foals (<12 hour to 48 days). METHODS: Prospective validation study. IgG concentrations were measured using RID (gold standard), POC-TIA, and POC-ELISA. Agreement between assays was assessed using Bland-Altman analysis. Sensitivity and specificity were calculated using ROC curves. Inter- and intra-assay coefficients of variation (CVs) and linearity were evaluated for POC-TIA. RESULTS: The mean bias (95% limits of agreement) between RID and POC-TIA was -4 (-185 to 176), 27 (-201 to 255), and 308 (-377 to 993) mg/dL for samples with IgG concentrations of <400, 400-800, and >800 mg/dL, respectively. Sensitivity and specificity at optimal cutoff were 94 and 100% for the POC-TIA and 94 and 100% for the POC-ELISA to detect IgG <400 mg/dL, and 85 and 87% (POC-TIA) and 69 and 79% (POC-ELISA) to detect IgG ≤800 mg/dL. Intra- and interassay CVs for POC-TIA ranged between 1.6-3.8 and 11.9-18.8%, respectively. Linearity of the dilution series was preserved (R2 > 0.96). CONCLUSIONS AND CLINICAL IMPORTANCE: The POC-TIA provided unambiguous results and had sufficient sensitivity, specificity, accuracy, and precision to be used as an alternative to other POC tests to assess FTPI in foals.

Atrial fibrillation management in a breeding stallion.

A 20-year-old warmblood breeding stallion presented to a University practice for semen collection and evaluation was incidentally diagnosed with atrial fibrillation (AF). Electrocardiogram recordings during breeding revealed inappropriately rapid tachycardia and occasional ventricular premature depolarizations/aberrant ventricular conduction. Transvenous electrical cardioversion was performed. After successful cardioversion the horse displayed supraventricular ectopy and atrial contractile dysfunction and was administered sotalol hydrochloride in an attempt to decrease the risk of AF recurrence. Supraventricular ectopy and echocardiographic evidence of atrial dysfunction gradually improved and normalized over 6 months. No direct adverse effects of the chronic anti-arrhythmic treatment were observed and libido and semen quality were unaffected. AF recurred 6 months after cardioversion and sotalol therapy was continued to control the ventricular ectopy/aberrant ventricular conduction during semen collection. Considerations regarding pathologic arrhythmias and inappropriately high heart rates in breeding stallions with AF may be similar to those in riding horses. Sotalol hydrochloride was a safe anti-arrhythmic drug in the management of this case.

Echocardiographic Assessment of Left Atrial Size and Function in Warmblood Horses: Reference Intervals, Allometric Scaling, and Agreement of Different Echocardiographic Variables.

BACKGROUND: Echocardiographic assessment of left atrial (LA) size and function in horses is not standardized. OBJECTIVES: The aim of this study was to establish reference intervals for echocardiographic indices of LA size and function in Warmblood horses and to provide proof of concept for allometric scaling of variables and for the clinical use of area-based indices. ANIMALS: Thirty-one healthy Warmblood horses and 91 Warmblood horses with a primary diagnosis of mitral regurgitation (MR) or aortic regurgitation (AR). METHODS: Retrospective study. Echocardiographic indices of LA size and function were measured and scaled to body weight (BWT). Reference intervals were calculated, the influence of BWT, age, and valvular regurgitation on LA size and function was investigated and agreement between different measurements of LA size was assessed. RESULTS: Allometric scaling of variables of LA size allowed for correction of differences in BWT. Indices of LA size documented LA enlargement with moderate and severe MR and AR, whereas most indices of LA mechanical function were not significantly altered by valvular regurgitation. Different indices of LA size were in fair to good agreement but still lead to discordant conclusions with regard to assessment of LA enlargement in individual horses. CONCLUSIONS AND CLINICAL IMPORTANCE: Allometric scaling of echocardiographic variables of LA size is advised to correct for differences in BWT among Warmblood horses. Assessment of LA dimensions should be based on an integrative approach combining subjective evaluation and assessment of multiple measurements, including area-based variables. The clinical relevance of indices of LA mechanical function remains unclear when used in horses with mitral or aortic regurgitation.

Clinical and echocardiographic findings in an 8 year old Brown Swiss cow with myocardial abscess.

Intramyocardial abscesses are rare in cattle and may lead to unspecific clinical signs. This case report describes the clinical and echocardiographic findings in an 8 year old Brown Swiss cow presented with an intramural myocardial abscess. The main clinical findings were anorexia, drop in milk yield, fever, tachycardia, and hyperfibrinogenemia. Neither heart murmurs nor cardiac arrhythmias were present on auscultation. Transthoracic echocardiographic examination revealed a prominent intramural mass embedded in the left ventricular free wall and bulging into the lumen of the left ventricle. Diagnosis was confirmed at necropsy. A culture of the abscess grew Trueperella pyogenes.

Left Ventricular Function After Prolonged Exercise in Equine Endurance Athletes.

BACKGROUND: Prolonged exercise in human athletes is associated with transient impairment of left ventricular (LV) function, known as cardiac fatigue. Cardiac effects of prolonged exercise in horses remain unknown. OBJECTIVES: To investigate the effects of prolonged exercise on LV systolic and diastolic function in horses. ANIMALS: Twenty-six horses competing in 120-160 km endurance rides. METHODS: Cross-sectional field study. Echocardiography was performed before and after rides, and the following morning, and included two-dimensional echocardiography, anatomical M-mode, pulsed-wave tissue Doppler imaging, and two-dimensional speckle tracking. Correlation between echocardiographic variables and cardiac troponin I was evaluated. RESULTS: Early diastolic myocardial velocities decreased significantly in longitudinal (baseline: -17.4 ± 2.4cm/s; end of ride: -15.8 ± 3.2cm/s (P = .013); morning after: -15.4 ± 3.0cm/s (P = .0033)) and radial directions (-32.8 ± 3.4cm/s; -28.1 ± 5.8cm/s (P < .001); -26.4 ± 5.5cm/s (P < .001)). Early diastolic strain rates decreased significantly in longitudinal (1.58 ± 0.27s(-1) ; 1.45 ± 0.26s(-1) (P = .036); 1.41 ± 0.25s(-1) (P = .013)) and circumferential directions (2.43 ± 0.29s(-1) ; 1.96 ± 0.46s(-1) (P < .001); 2.11 ± 0.32s(-1) (P < .001)). Systolic variables showed ambiguous results. No correlations with serum cardiac troponin I concentrations were evident. CONCLUSIONS AND CLINICAL IMPORTANCE: Prolonged exercise in horses is associated with impaired LV diastolic function. Reduced ventricular filling persisted for 7-21 hours despite normalization of biochemical indicators of hydration status, indicating that the observed changes were not entirely related to altered preload conditions. The clinical relevance of cardiac fatigue in horses remains uncertain.

Effects of 10% hydroxyethyl starch (HES 200/0.5) solution in intraoperative fluid therapy management of horses undergoing elective surgical procedures.

The aim of the present study was to investigate the effect of pentastarch on colloid osmotic pressure (COP) and cardiopulmonary function during and up to 24 h after anaesthesia in horses. Twenty-five systemically healthy horses were anaesthetised using isoflurane-medetomidine balanced anaesthesia. Twelve were assigned to treatment with hydroxyethyl starch (HES) (H group) and 13 to no HES (NH group). In the H group, 6 mL/kg of pentastarch 10% HES (200/0.5) was infused over 1 h starting 30 min after induction of anaesthesia. Horses of the NH group received an equal amount of lactated Ringer's solution (LRS). COP and blood biochemical, cardiopulmonary and anaesthesia-related variables were measured at different time points before and after treatment. Pentastarch was effective in correcting the decrease in COP observed with LRS administration. No differences between treatments were detected for blood glucose, lactate, total proteins and electrolytes. Packed cell volume was lower with the H group immediately after finishing HES-administration and for an additional 30 min. In all horses, all blood biochemical variables other than lactate returned to normal after 12 h. No clinically relevant differences between treatments were detected for cardiopulmonary variables, although 23.1% of the NH-horses needed rescue-HES to maintain cardiovascular function, while none of the H-horses needed additional colloids. Overall, 6 mL/kg HES (200/0.5) was found to be effective in maintaining COP during anaesthesia in systemically healthy horses. Intermediate and long-term effects were below the limit of detection. The potentially beneficial effects on cardiovascular function need further investigation, especially in critically ill horses.