Accuracy and Precision of Noninvasive Blood Pressure in Normo-, Hyper-, and Hypotensive Standing and Anesthetized Adult Horses

BACKGROUND: Blood pressure is relevant to the diagnosis and management of many medical, cardiovascular and critical diseases. The accuracy of many commonly used noninvasive blood pressure (NIBP) monitors and the accuracy of NIBP measurements in hypo‐ and hypertensive standing horses has not been determined. HYPOTHESIS/OBJECTIVES: The objective of this study was to investigate the accuracy of an oscillometric BP monitor in standing horses before and during pharmacologically induced hyper‐ and hypotension and to compare results in standing and anesthetized horses. ANIMALS: Eight standing mares from a research herd (SG) and eight anesthetized horses from a hospital population (AG). METHODS: Prospective experimental and observational studies. Invasive blood pressure (IBP) and NIBP, corrected to heart level, were measured simultaneously. In the SG hyper‐ and hypotension were induced by administration of phenylephrine (3 μg/kg/min IV for 15 minutes) and acepromazine (0.05 mg/kg IV), respectively. In the AG NIBP and IBP were recorded during regular hospital procedures. RESULTS: There was a significant correlation between mean NIBP and IBP in standing (R = 0.88, P < .001) and anesthetized horses (R = 0.81, P < .001). The mean bias (lower, upper limit of agreement) was 16.4(−16.1, 48.9) mmHg for mean BP in the SG and 0.5(−22.3, 23.2) mmHg in the AG. The NIBP device was capable of identifying the increase and decrease in BP in all horses, but in the SG significant correlation between NIBP and IBP was only detected for the normotensive phase. CONCLUSION AND CLINICAL IMPORTANCE: While the evaluated oscillometric BP device allowed estimation of BP and adequately differentiated marked trends, the accuracy and precision were low in standing horses

Gastrointestinal ultrasonography of normal Standardbred neonates and frequency of asymptomatic intussusceptions.

BACKGROUND Ultrasonographic appearance of the gastrointestinal (GI) tract of equine neonates has not been completely described. OBJECTIVES To describe (1) sonographic characteristics of the GI segments in normal nonsedated equine neonates, (2) intra- and interobserver variation in wall thickness, and (3) the sonographic appearance of asymptomatic intussusceptions, and (4) to compare age and sonographic findings of foals with and without asymptomatic intussusceptions. ANIMALS Eighteen healthy Standardbred foals ≤5 days of age. METHODS Prospective, cross-sectional blinded study. Gastrointestinal sonograms were performed stall-side. Intraobserver variability in wall thickness measurements was determined by calculating the coefficient of variation (CV). The Bland-Altman method was used to assess interobserver bias. Student's t-test and Fisher's exact test were used to test the association among presence of intussusceptions, age, and selected sonographic findings. RESULTS The reference ranges (95% predictive interval) for wall thickness were 1.6-3.6 mm for the stomach, 1.9-3.2 mm for the duodenum, 1.9-3.1 mm for the jejunum, 1.3-2.2 mm for the colon, and 0.8-2.7 mm for the cecum. Intraobserver wall thickness CV ranged from 8 to 21% for the 2 observers for 5 gastrointestinal segments. The interobserver bias for wall thickness measurements was not significant except for the stomach (0.14 mm, P < .05) and duodenum (0.29 mm, P < .05). Diagnostic images of mural blood flow could not be obtained. Asymptomatic intussusceptions were found in 10/18 neonates. Associations between sonographic variables or age and the presence of intussusceptions were not found. CONCLUSIONS AND CLINICAL IMPORTANCE Sonographic characteristics of the GI tract of normal Standardbred neonates can be useful in evaluating ill foals. Asymptomatic small intestinal intussusceptions occur in normal Standardbred neonates

Studies in equine cardiology

La presencia de enfermedad cardiaca puede tener repercusiones serias sobre la salud y el bienestar de los equinos pero el riesgo a las personas, asociado con el desarrollo de colapso cardiovascular o de muerte súbita cardiaca hacen de la cardiología equina una disciplina con implicaciones que van más allá de la salud animal. La tesis aquí presentada trata de aportar conocimientos sobre problemas cardiacos equinos. En el primer estudio de esta tesis se estudió los efectos de la hemorragia aguda en la concentración plasmática de un marcador específico de daño miocárdico, como es la troponina cardiaca I, y en el desarrollo de arritmias cardiacas. Para realizar este estudio diseñamos un estudio prospectivo en el que un grupo de caballos con hemorragia aguda se comparó a un grupo control. El estudio determinó que la hemorragia aguda causa daño miocárdico que puede ser detectado midiendo la concentración plasmática de troponina cardiaca I y que la presencia de arritmias es frecuente en caballos hospitalizados debido a la presencia de hemorragia aguda. EL segundo estudio de esta tesis se diseñó para estudiar la apariencia clínica, ecocardiográfica y anatomopatológica de la cardiomiopatía hipertensiva en caballos. Diseñamos un estudio retrospectivo en el cual se revisaron los archivos de la Universidad de Pensilvania desde 1995 a 2011 para encontrar casos con hipertrofia del miocardio del ventrículo izquierdo e hipertensión. A partir de esta información se describió la presencia de cardiomiopatía hipertensiva como una comorbilidad en caballos con laminitis y fallo renal crónico. Este problema clínico no había sido descrito previamente en equinos. La cardiomiopatía hipertensiva debería de considerarse en caballos con hipertensión y se debe añadir a la lista de diagnósticos diferenciales en los caballos que presentan hipertrofia del ventrículo izquierdo. El tercer estudio de esta tesis investigó la presencia de un estado de hipercoagulación en caballos con fibrilación atrial. La fibrilación atrial es la arritmia clínicamente mas relevante en caballos y humanos y en humanos causa un estado de hipercoagulación que provoca que las complicaciones tromboembólicas sean la mayor causa de morbilidad y mortalidad en estos pacientes. Diseñamos un estudio prospectivo control en el cual los tests de coagulación más utilizados en medicina equina se realizaron en muestras de sangre obtenidas de caballos con fibrilación atrial y de un grupo control. La proporción de caballos con D-dímeros, paneles de coagulación y resultados anormales fue mayor en el grupo de caballos con fibrilación atrial. La antitrombina fue significativamente mas baja en el grupo de caballos con fibrilación atrial. Ninguno de los caballos mostró signos clínicos de hipercoagulación o tromboembolismo. Este estudio demostró que los caballos en fibrilación atrial presentan un estado subclínico de hipercoagulacion sin sintomatología clínica de tromboembolismo. Como conclusión, los tres estudios que forman parte de esta tesis doctoral han contestado cuestiones relevantes que no habían sido investigadas previamente. La hemorragia aguda causa daño miocárdico y arritmias en caballos. Caballos con laminitis y enfermedad renal crónica pueden desarrollar cardiomiopatía hipertensiva y los caballos con fibrilación atrial permanecen en un estado de hipercoagulabilidad sin consecuencias tromboembólicas.The presence of cardiac disease can have serious repercussions to horses’ health and wellbeing but the risks for humans associated with equine cardiovascular collapse or sudden cardiac death make equine cardiology a discipline that has implications that go beyond animal health. The thesis presented here was designed to gain further knowledge in equine cardiac problems The first study of this thesis studied the effects of acute hemorrhage on the plasma concentration of a marker of myocardial injury (cTnI) and in the development of cardiac arrhythmias. We designed a prospective controlled study in which a group of horses presented with acute hemorrhage were compared to a control group. We concluded that acute hemorrhage results in myocardial injury that can be detected by measuring cTnI and that arrhythmias are frequent in hospitalized horses with acute hemorrhage. The goal of the second study of this thesis was to study the clinical, echocardiographic and pathological appearance of hypertensive cardiomyopathy (HC) in horses. To achieve this goal we designed a retrospective study in which the medical records of the University of Pennsylvania’s New Bolton Center (between 1995 and 2011) were searched for the presence of horses with myocardial hypertrophy and hypertension. We described the presence of HC as a comorbid diagnosis in horses with laminitis or chronic renal failure. This clinical entity had not been previously diagnosed in horses. Hypertensive cardiomyopathy should be borne in mind when evaluating horses with hypertension and added to the list of differentials diagnoses for horses that present left ventricular hypertrophy. The third part of this thesis had the motivation of investigating the presence of a hypercoagulable state in horses with atrial fibrillation. Atrial fibrillation is the most common and clinically relevant arrhythmia in horses and in humans. Humans in atrial fibrillation are in a hypercoagulable state that makes stroke and thromboembolism the major cause of morbidity and mortality in patients with this rhythm disturbance. We designed a prospective controlled study in which common tests to evaluate coagulation and fibrinolysis in horses were performed on blood samples obtained from equine patients with atrial fibrillation and in a control group. The proportion of horses with abnormal D-dimer concentrations, abnormal coagulation profiles and the proportion of abnormal coagulation tests was larger in the atrial fibrillation group than in the control group. Antithrombin activity was lower in the atrial fibrillation group. No clinical signs of hypercoagulability or thrombogenesis were detected in any of the horses. This study demonstrated that atrial fibrillation causes a state of hypercoagulability in horses without thromboembolic consequences. In conclusion, the three studies have contributed to the body of knowledge in equine cardiology and have answered relevant questions that had not been previously investigated. Acute hemorrhage causes myocardial injury and arrhythmias during acute hemorrhage in horses. Horses with laminitis or chronic renal failure can develop HC and horses in atrial fibrillation present subclinical hypercoagulation without thromboembolic consequences

Studies in equine cardiology

La presencia de enfermedad cardiaca puede tener repercusiones serias sobre la salud y el bienestar de los equinos pero el riesgo a las personas, asociado con el desarrollo de colapso cardiovascular o de muerte súbita cardiaca hacen de la cardiología equina una disciplina con implicaciones que van más allá de la salud animal. La tesis aquí presentada trata de aportar conocimientos sobre problemas cardiacos equinos. En el primer estudio de esta tesis se estudió los efectos de la hemorragia aguda en la concentración plasmática de un marcador específico de daño miocárdico, como es la troponina cardiaca I, y en el desarrollo de arritmias cardiacas. Para realizar este estudio diseñamos un estudio prospectivo en el que un grupo de caballos con hemorragia aguda se comparó a un grupo control. El estudio determinó que la hemorragia aguda causa daño miocárdico que puede ser detectado midiendo la concentración plasmática de troponina cardiaca I y que la presencia de arritmias es frecuente en caballos hospitalizados debido a la presencia de hemorragia aguda. EL segundo estudio de esta tesis se diseñó para estudiar la apariencia clínica, ecocardiográfica y anatomopatológica de la cardiomiopatía hipertensiva en caballos. Diseñamos un estudio retrospectivo en el cual se revisaron los archivos de la Universidad de Pensilvania desde 1995 a 2011 para encontrar casos con hipertrofia del miocardio del ventrículo izquierdo e hipertensión. A partir de esta información se describió la presencia de cardiomiopatía hipertensiva como una comorbilidad en caballos con laminitis y fallo renal crónico. Este problema clínico no había sido descrito previamente en equinos. La cardiomiopatía hipertensiva debería de considerarse en caballos con hipertensión y se debe añadir a la lista de diagnósticos diferenciales en los caballos que presentan hipertrofia del ventrículo izquierdo. El tercer estudio de esta tesis investigó la presencia de un estado de hipercoagulación en caballos con fibrilación atrial. La fibrilación atrial es la arritmia clínicamente mas relevante en caballos y humanos y en humanos causa un estado de hipercoagulación que provoca que las complicaciones tromboembólicas sean la mayor causa de morbilidad y mortalidad en estos pacientes. Diseñamos un estudio prospectivo control en el cual los tests de coagulación más utilizados en medicina equina se realizaron en muestras de sangre obtenidas de caballos con fibrilación atrial y de un grupo control. La proporción de caballos con D-dímeros, paneles de coagulación y resultados anormales fue mayor en el grupo de caballos con fibrilación atrial. La antitrombina fue significativamente mas baja en el grupo de caballos con fibrilación atrial. Ninguno de los caballos mostró signos clínicos de hipercoagulación o tromboembolismo. Este estudio demostró que los caballos en fibrilación atrial presentan un estado subclínico de hipercoagulacion sin sintomatología clínica de tromboembolismo. Como conclusión, los tres estudios que forman parte de esta tesis doctoral han contestado cuestiones relevantes que no habían sido investigadas previamente. La hemorragia aguda causa daño miocárdico y arritmias en caballos. Caballos con laminitis y enfermedad renal crónica pueden desarrollar cardiomiopatía hipertensiva y los caballos con fibrilación atrial permanecen en un estado de hipercoagulabilidad sin consecuencias tromboembólicas.The presence of cardiac disease can have serious repercussions to horses' health and wellbeing but the risks for humans associated with equine cardiovascular collapse or sudden cardiac death make equine cardiology a discipline that has implications that go beyond animal health. The thesis presented here was designed to gain further knowledge in equine cardiac problems The first study of this thesis studied the effects of acute hemorrhage on the plasma concentration of a marker of myocardial injury (cTnI) and in the development of cardiac arrhythmias. We designed a prospective controlled study in which a group of horses presented with acute hemorrhage were compared to a control group. We concluded that acute hemorrhage results in myocardial injury that can be detected by measuring cTnI and that arrhythmias are frequent in hospitalized horses with acute hemorrhage. The goal of the second study of this thesis was to study the clinical, echocardiographic and pathological appearance of hypertensive cardiomyopathy (HC) in horses. To achieve this goal we designed a retrospective study in which the medical records of the University of Pennsylvania's New Bolton Center (between 1995 and 2011) were searched for the presence of horses with myocardial hypertrophy and hypertension. We described the presence of HC as a comorbid diagnosis in horses with laminitis or chronic renal failure. This clinical entity had not been previously diagnosed in horses. Hypertensive cardiomyopathy should be borne in mind when evaluating horses with hypertension and added to the list of differentials diagnoses for horses that present left ventricular hypertrophy. The third part of this thesis had the motivation of investigating the presence of a hypercoagulable state in horses with atrial fibrillation. Atrial fibrillation is the most common and clinically relevant arrhythmia in horses and in humans. Humans in atrial fibrillation are in a hypercoagulable state that makes stroke and thromboembolism the major cause of morbidity and mortality in patients with this rhythm disturbance. We designed a prospective controlled study in which common tests to evaluate coagulation and fibrinolysis in horses were performed on blood samples obtained from equine patients with atrial fibrillation and in a control group. The proportion of horses with abnormal D-dimer concentrations, abnormal coagulation profiles and the proportion of abnormal coagulation tests was larger in the atrial fibrillation group than in the control group. Antithrombin activity was lower in the atrial fibrillation group. No clinical signs of hypercoagulability or thrombogenesis were detected in any of the horses. This study demonstrated that atrial fibrillation causes a state of hypercoagulability in horses without thromboembolic consequences. In conclusion, the three studies have contributed to the body of knowledge in equine cardiology and have answered relevant questions that had not been previously investigated. Acute hemorrhage causes myocardial injury and arrhythmias during acute hemorrhage in horses. Horses with laminitis or chronic renal failure can develop HC and horses in atrial fibrillation present subclinical hypercoagulation without thromboembolic consequences

Evaluation of coagulation and fibrinolysis in horses with atrial fibrillation

OBJECTIVE To evaluate horses with atrial fibrillation for hypercoagulability; plasma D-dimer concentrations, as a marker of a procoagulant state; and a relationship between coagulation profile results and duration of atrial fibrillation or presence of structural heart disease. DESIGN Case-control study. ANIMALS Plasma samples from 42 horses (25 with atrial fibrillation and 17 without cardiovascular or systemic disease [control group]). PROCEDURES Results of hematologic tests (ie, plasma fibrinogen and D-dimer concentrations, prothrombin and activated partial thromboplastin times, and antithrombin activity) in horses were recorded to assess coagulation and fibrinolysis. Historical and clinical variables, as associated with a hypercoagulable state in other species, were also recorded. RESULTS Horses with atrial fibrillation and control horses lacked clinical signs of hypercoagulation or thromboembolism. Compared with control horses, horses with atrial fibrillation had significantly lower antithrombin activity. No significant differences in plasma fibrinogen and D-dimer concentrations and prothrombin and activated partial thromboplastin times existed between horse groups. In horses with atrial fibrillation versus control horses, a significantly larger proportion had an abnormal plasma D-dimer concentration (10/25 vs 2/17), test results indicative of subclinical activated coagulation (18/25 vs 6/17), or abnormal coagulation test results (25/121 vs 7/85), respectively. CONCLUSIONS AND CLINICAL RELEVANCE Horses with atrial fibrillation did not have clinical evidence of a hypercoagulable state, but a higher proportion of horses with atrial fibrillation, compared with control horses, did have subclinical activated coagulation on the basis of standard coagulation test results

Cardiovascular findings in ponies with equine metabolic syndrome

OBJECTIVE To determine whether hypertension, high sympathetic tone, resting and exercising arrhythmias, and echocardiographic changes consistent with hypertensive cardiomyopathy were associated with equine metabolic syndrome (EMS) in ponies. DESIGN Prospective case-control study. ANIMALS 19 privately owned ponies with a diagnosis of EMS (history of laminitis, body condition score ≥ 7/9, cresty neck score ≥ 3/5, and abnormal oral sugar test result; cases) and 20 healthy control ponies. PROCEDURES Heart rate (HR), noninvasively measured arterial blood pressure (BP), markers of autonomic tone (splenic volume and HR variability), 24-hour and exercising ECGs, and echocardiograms were compared between cases and controls. RESULTS Compared with controls, cases had a higher mean ± SD HR (44.5 ± 7.5 beats/min vs 38.6 ± 6.8 beats/min) and median mean left ventricular wall thickness (2.0 cm vs 1.8 cm). No differences were identified between groups in BP, splenic volume, HR variability, and number of premature complexes in ECGs. Mean wall thickness was correlated with BP (r = 0.54), high-frequency power (r = -0.71), and ratio of low-to high-frequency power (ϕ = 0.66). Relative wall thickness was correlated with serum insulin concentration (r = 0.71). CONCLUSIONS AND CLINICAL RELEVANCE Ponies with EMS had myocardial hypertrophy that was correlated with insulin response to an oral sugar test, sympathetic and parasympathetic tone, and BP. The heterogeneity and limited sample size of this preliminary study should be considered when drawing conclusions. Cardiovascular changes associated with this syndrome deserve further attention

IMAGING DIAGNOSIS-MUSCULAR HYPERTROPHY OF THE SMALL INTESTINE AND PSEUDODIVERTICULA IN A HORSE.

A 14-year-old Thoroughbred gelding was presented for chronic colic and weight loss. Transcutaneous and transrectal abdominal ultrasonography revealed distended, thickened small intestine with primary thickening of the muscularis and a focally more thickened loop with an echoic structure crossing the wall from the mucosa to the serosa. Visualization of diffuse thickening of the muscularis (muscular hypertrophy of the small intestine) and a focal lesion (pseudodiverticulum) helped clinicians make informed decisions. This case illustrates the importance of transabdominal and transrectal ultrasonography in horses with chronic colic and the relevance of considering the abnormalities in layering pattern of the intestinal wall

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