Effects of norepinephrine and combined norepinephrine and fenoldopam infusion on systemic hemodynamics and indices of renal function in normotensive neonatal foals

Background: Norepinephrine increases arterial blood pressure but may have adverse effects on renal blood flow. Fenoldopam, a dopamine-1 receptor agonist, increases urine output in normotensive foals. The combination of norepinephrine and fenoldopam may lead to improved renal perfusion compared with an infusion of norepinephrine alone. The combined effects of these drugs have not been reported in the horse.
Hypothesis: Norepinephrine will alter the hemodynamic profile of foals without affecting renal function. Addition of fenoldopam will change the renal profile during the infusions without changing the hemodynamic profile.
Animals: Five conscious pony foals.
Methods: Each foal received norepinephrine (0.3 μg/kg/min), combined norepinephrine (0.3 μg/kg/min) and fenoldopam (0.04 μg/kg/min), and a control dose of saline in a masked, placebo-controlled study. Heart rate (HR), arterial blood pressure (direct), and cardiac output (lithium dilution) were measured, and systemic vascular resistance (SVR), stroke volume, cardiac index (CI), and stroke volume index were calculated. Urine output, creatinine clearance, and fractional excretion of electrolytes were measured.
Results: Norepinephrine and a combined norepinephrine and fenoldopam infusion increased arterial blood pressure, SVR, urine output, and creatinine clearance and decreased HR and CI compared with saline. The combination resulted in higher HR and lower arterial blood pressure than norepinephrine alone.
Conclusions and Clinical Importance: Norepinephrine might be useful for hypotensive foals, because in normal foals, this infusion rate increases SVR without negatively affecting renal function (creatinine clearance increased). Fenoldopam does not provide additional benefit to renal function. These findings warrant further investigation.     

Resting concentrations of cardiac troponin I in fit horses and effect of racing

ObjectivesTo determine normal resting values for cardiac troponin I (cTnI) in healthy Standardbred, Thoroughbred and Warmblood horses and investigate if racing has an influence on cTnI concentrations.BackgroundMeasuring cTnI concentrations in plasma is the gold standard for detecting myocardial injury in humans. Cardiac troponin I is highly conserved between species and has gained interest as a marker for cardiac injury in horses. Increased levels of cTnI have been reported in association with endurance and short-term strenuous exercise on a treadmill in horses. However, the effect of true racing conditions has not yet been reported.Animals, materials and methodsBlood samples for analysis of cTnI concentrations in plasma were collected from 67 Standardbred racehorses, 34 Thoroughbred racehorses and 35 Warmblood dressage horses at rest. Blood samples were also collected prior to and after racing in 22 Standardbred racehorses and 6 Thoroughbred racehorses.ResultsAll horses except one had resting plasma cTnI concentrations <0.022 μg/L. Mild increases in cTnI concentrations were seen in some horses 1–2 h after the race (1/17 Standardbreds and 2/6 Thoroughbreds) as well as 10–14 h after the race (4/21 Standardbreds and 1/6 Thoroughbreds).ConclusionsResting cTnI concentrations in horses are low but mildly elevated cTnI concentrations may be detected in some horses 1–14 h after racing. These findings could be of importance when evaluating horses with suspected cardiac disease that recently have performed hard exercise.     

A Comparison of Daily Rhythm of Creatinine and Creatine Kinase in the Sedentary and Athlete Horse

The goal of this study was to investigate the existence of a daily rhythm of creatinine or creatine kinase (CK) and the influence of physical exercise on these rhythms. Blood samples from 20 Sella Italiana horses were collected every 4 hours for 48 consecutive hours via an intravenous cannula inserted into the jugular vein. The horses were divided into two equal groups (Sedentary [S] and Athlete [A]). After 2 weeks of rest, athletes (AR) were subjected again to sample collection every 4 hours for 48 consecutive hours, and sera creatinine and CK were assessed. Statistical analysis of the data was performed by one-way repeated analysis of variance (ANOVA), paired Student's t-test, unpaired Student's t-test, and analysis of single cosinor method. Cosinor analysis identified the periodic parameters and their acrophases (expressed in hours) during the 2 days of monitoring. In all horses, we found a highly significant effect of time of the day on the studied parameters (P < .01). Statistically significant differences were observed for mean serum CK values between sedentary and athlete horses. The application of the periodic model showed a daily rhythm of the parameters studied in all experimental conditions. The results obtained during the experimental period indicated a daily rhythm of creatinine and CK in sedentary and athlete horses and also indicated that physical exercise was able to influence amplitude, acrophase, and robustness of the creatinine and CK circadian rhythm.     

激光麻醉对马心功能影响的研究

以电生物阻抗技术对10匹实验马进行了监测,结果表明氦氖激光麻醉对马的心脏功能无不良影响     

采用血液遗传标记对马亲仔关系案例的检测与分析

采用16个血液遗传住点对北京华骏育马场的275组及中国马术协会所提供的2组马匹进行了亲仔关系的鉴定,并对其中典型的8组马匹进行了分析。得出结果如下：6匹幼驹与其指定父母双方均不符而被排除亲仔关系,经验证确认为属于幼驹被串换;在所检的遗传住点中,以D血型、运铁蛋白(Tf)、蛋白酶抑制剂(Pi)和6-磷酸葡萄糖脱氢酶(6-PGD)检测亲仔关系错误的效果最好;在根据自身外貌无法断定为非纯血马的情况下,采用从非纯血马亲本来鉴定是行之有效的。     

Transvenous electrical cardioversion of equine atrial fibrillation: patient factors and clinical results in 72 treatment episodes

BACKGROUND: Transvenous electrical cardioversion (TVEC) has been developed for treatment of atrial fibrillation (AF) in horses. The relationship among patient variables, treatment response, and outcome in a typical referral population has not been evaluated. HYPOTHESIS: Patient variables such as age, sex, weight, and duration of arrhythmia affect prognosis for response to treatment and the energy level at which cardioversion occurs. ANIMALS: TVEC was applied to 72 episodes of lone AF in 63 client-owned performance horses, with the majority (54) being Standardbred racehorses. METHODS: Catheterization of the right atrium (RA) and pulmonary artery (PA) through the jugular vein was used for electrode placement before horses were placed under general anesthesia. Biphasic, truncated exponential shock waves were delivered at incremental energy levels until cardioversion was achieved or a maximum single-energy level of 300 J was reached (cumulative energy 50-1,960 J). A multivariate model was constructed to evaluate influence of patient factors on cardioversion energy. RESULTS: Cardioversion was achieved in 71 of 72 episodes (62 of 63 horses) at a mean energy of 165.43 +/- 8.75 J. Cardioversion energy was higher for females than for males, and for interaction terms, weight was negatively related to energy in females and positively related in males. Age was positively related to cardioversion energy in females. No relationship was identified between duration of arrhythmia before treatment and prognosis for response or cardioversion energy. CONCLUSIONS AND CLINICAL IMPORTANCE: TVEC is highly effective in the treatment of lone AF in horses. Although age and sex influence cardioversion energy level, duration of arrhythmia does not.     

Variability of Selected Biochemical Parameters in Young Stallions During the 100-day Performance Test

The aim of the study was to evaluate variations in biochemical blood parameters of stallions during a 100-day performance test. The study was carried out with 20 clinically healthy stallions aged 3-4 years. The degree of adaptation to exercise loads during a 100-day performance test was assessed three times: (I) on the first day of training, (II) on the 46th day of training, and (III) on the 97^th day of training. Sample collection and basic clinical tests were performed before training (1), directly after training (2), and after a 30-minute rest (3). Venous blood samples were analyzed for the concentration of total protein, glucose (GLU), and lactate, the activity of lactate dehydrogenase (LDH), and creatine kinase (CK), and total antioxidant status (TAS). Postexercise changes in the analyzed parameters showed that the loads were of moderate intensity. As a result of the 100-day training, postexercise variation in GLU concentration and CK and LDH activity was lower than at the beginning, which indicates that the body was stimulated to adapt to performing exercise tasks. The resting level of TAS was also found to increase. The results obtained suggest that the stallions are well prepared for increasing exercise loads.