Two-dimensional, M-mode and left atrial velocity echocardiographic measurements in healthy Norwegian-Swedish Coldblooded Trotters.

INTRODUCTION: The Norwegian-Swedish Coldblooded Trotter (NSCT) is an important breed in Norwegian and Swedish harness racing. In spite of this, little is known about its cardiac measurements and factors that may influence these. The aims of this study were to establish reference intervals (RI) for a series of conventional echocardiographic variables, primarily of the left heart, in NSCTs in race training and to evaluate any effects age, gender, estimated body weight (EBW), number of starts and racing performance may have on these. ANIMALS: Sixty-three apparently healthy NSCTs in race training. METHODS: Observational study, convenience sampling. All horses were examined unsedated in their normal stabling environment. Auscultatory and echocardiographic examinations were performed. Means, standard deviations, medians and confidence intervals of the RI limits were used to summarize the data. The relationship between selected echocardiographic variables and age, gender, EBW, racing performance and number of starts were explored using linear regression analyses. RESULTS: Reference intervals were determined for routinely used echocardiographic variables. Data for left atrial velocity were also obtained. Increasing age, number of starts and money earned significantly increased all cardiac measurements. Males had significantly higher ventricular measurements than females. Great vessel measurements increased with increasing EBW. Horses with faster recorded racing times had generally significantly increased cardiac measurements. Clinically insignificant valvular regurgitation was a common finding, particularly at the tricuspid and pulmonary valves. CONCLUSIONS: The RIs described and the factors that may affect these will assist clinicians in interpreting echocardiograms of NSCTs with suspected cardiac disease or poor performance.

Pre- and post-race serum cardiac troponin T concentrations in Standardbred racehorses.

Elevated cardiac troponin T (cTnT) concentrations may provide evidence of myocardial injury but physiological post-exercise release also occurs. Reference intervals are not fully established in horses making interpretation difficult. The aims of this study were to establish an upper reference limit for serum cTnT, compare pre-and post-race serum cTnT concentrations, and to evaluate factors that may influence these in a population of healthy, race-fit Standardbred racehorses. Serum samples were collected pre- (n = 108) and 1-2 h post-racing (n = 101) and analysed using a high sensitivity-cTnT assay. Reference limits with 90% confidence intervals (CI) were calculated by non-parametric methods using the bootstrap method. Effects of sex, age, racing speed, distance, placings and track surface were assessed by fitting generalized linear models with an identity link function and inverse Gaussian distribution. The upper reference limit for serum cTnT concentration was 27.4 ng/L (90% CI 13.1-32.0). The median serum cTnT concentration was significantly higher 1-2 h post-racing compared to pre-racing (P < 0.001). Age and sex did not significantly affect serum cTnT concentrations pre-racing (P = 0.5 and P = 0.11). Cardiac troponin T concentrations were significantly higher post-racing in females (P = 0.018). Racing speed and placings had no effect on serum cTnT concentrations post-race (P = 0.71 and P = 0.66). The study contributed towards establishing an upper reference limit for serum cTnT concentrations in a population of race-fit Standardbreds and evaluated factors that may have influenced the results obtained.

Caprine arthritis encephalitis and caseous lymphadenitis in goats: use of bulk tank milk ELISAs for herd-level surveillance.

The objective of this study was to evaluate the diagnostic performance of two ELISA tests applied to bulk tank milk (BTM) as the first part of a two-step test scheme for the surveillance of caprine arthritis encephalitis (CAE) and caseous lymphadenitis (CLA) infections in goats. The herd-level BTM tests were assessed by comparing them to the test results of individual serological samples. The potential for refining the cut-off levels for BTM tests used as surveillance tools in a population recently cleared of infection was also investigated. Data was gathered on serum (nCAE =9702 and nCLA=13426) and corresponding BTM (nCAE=78 and nCLA=123) samples from dairy goat herds enrolled in the Norwegian disease control and eradication programme 'Healthier Goats'. The results showed that the sensitivity and specificity of the CAE ELISA BTM test with respect to detecting ≥2 per cent within-herd prevalence were 72.7 per cent and 86.6 per cent, respectively. For the CLA ELISA BTM the sensitivity and specificity were 41.4 per cent and 81.7 per cent, respectively, for the same goal of detection. The results suggest that BTM testing can be applied as a cost-effective first step for early detection of CAE and CLA infection.

Antinociceptive effects of three escalating dexmedetomidine and lignocaine constant rate infusions in conscious horses.

Dexmedetomidine and lignocaine IV are used clinically to provide analgesia in horses. The aims of this study were to investigate the antinociceptive effects, plasma concentrations and sedative effects of 2, 4 and 6 µg/kg/h dexmedetomidine IV, with a bolus of 0.96 µg/kg preceding each continuous rate infusion (CRI), and 20, 40 and 60 µg/kg/min lignocaine IV, with a bolus of 550 µg/kg preceding each CRI, in 10 Swiss Warmblood horses. Electrically elicited nociceptive withdrawal reflexes were evaluated by deltoid muscle electromyography. Nociceptive threshold and tolerance were determined by electromyography and behaviour following single and repeated stimulation. Plasma concentrations of drugs were determined by liquid chromatography and mass spectrometry. Sedation was scored on a visual analogue scale. Dexmedetomidine increased nociceptive threshold to single and repeated stimulation for all CRIs, except at 2 µg/kg/h, where no increase in single stimulation nociceptive threshold was observed. Dexmedetomidine increased nociceptive tolerance to single and repeated stimulation at all CRIs. There was large individual variability in dexmedetomidine plasma concentrations and levels of sedation; the median plasma concentration providing antinociceptive effects to all recorded parameters was 0.15 ng/mL, with a range from <0.02 ng/mL (below the lower limit of quantification) to 0.25 ng/mL. Lignocaine increased nociceptive threshold and tolerance to single and repeated stimulation at CRIs of 40 and 60 µg/kg/min, corresponding to plasma lignocaine concentrations >600 ng/mL. Only nociceptive tolerance to repeated stimulation increased at 20 µg/kg/min lignocaine. Lignocaine at 40 µg/kg/min and dexmedetomidine at 4 µg/kg/h were the lowest CRIs resulting in consistent antinociception. Lignocaine did not induce significant sedation.

The Norwegian Healthier Goats program--modeling lactation curves using a multilevel cubic spline regression model.

In 2001, the Norwegian Goat Health Service initiated the Healthier Goats program (HG), with the aim of eradicating caprine arthritis encephalitis, caseous lymphadenitis, and Johne's disease (caprine paratuberculosis) in Norwegian goat herds. The aim of the present study was to explore how control and eradication of the above-mentioned diseases by enrolling in HG affected milk yield by comparison with herds not enrolled in HG. Lactation curves were modeled using a multilevel cubic spline regression model where farm, goat, and lactation were included as random effect parameters. The data material contained 135,446 registrations of daily milk yield from 28,829 lactations in 43 herds. The multilevel cubic spline regression model was applied to 4 categories of data: enrolled early, control early, enrolled late, and control late. For enrolled herds, the early and late notations refer to the situation before and after enrolling in HG; for nonenrolled herds (controls), they refer to development over time, independent of HG. Total milk yield increased in the enrolled herds after eradication: the total milk yields in the fourth lactation were 634.2 and 873.3 kg in enrolled early and enrolled late herds, respectively, and 613.2 and 701.4 kg in the control early and control late herds, respectively. Day of peak yield differed between enrolled and control herds. The day of peak yield came on d 6 of lactation for the control early category for parities 2, 3, and 4, indicating an inability of the goats to further increase their milk yield from the initial level. For enrolled herds, on the other hand, peak yield came between d 49 and 56, indicating a gradual increase in milk yield after kidding. Our results indicate that enrollment in the HG disease eradication program improved the milk yield of dairy goats considerably, and that the multilevel cubic spline regression was a suitable model for exploring effects of disease control and eradication on milk yield.