OBJECTIVE To compare the effects of 3 walkway cover types on temporospatial and ground reaction force measurements of dogs during gait analysis with a pressure-sensitive walkway (PSW). ANIMALS 35 client- and staff-owned dogs (25 nonlame and 10 lame). PROCEDURES In a crossover study design, all dogs were evaluated at a comfortable walk on a PSW to which 3 cover types (a 0.32-cm-thick corrugated vinyl mat or a 0.32- or 0.64-cm-thick polyvinyl chloride yoga mat) were applied in random order. Temporospatial and ground reaction force measurements were obtained and compared among cover types within the nonlame and lame dog groups. RESULTS Several variables, including maximum peak pressure, maximum force (absolute and normalized as a percentage of body weight), and vertical impulse (absolute and normalized) differed significantly in most comparisons among cover types for both nonlame and lame dogs. There was no significant difference in maximum force values between the 0.32-cm-thick corrugated vinyl and 0.64-cm-thick polyvinyl chloride cover types for both nonlame and lame dogs. CONCLUSIONS AND CLINICAL RELEVANCE To the authors’ knowledge, the cover type used during data collection with a PSW is rarely provided in published reports on this topic. The findings in this study suggested that to ensure that PSW data for dogs are collected in a standardized manner, the same cover type should be used during follow-up visits to evaluate clinical outcomes, for the duration of research studies, and at all locations for multi-institutional studies. The cover type should be specified in future PSW studies to allow direct comparisons of findings between studies.

OBJECTIVE To determine whether the lactate threshold of dogs could be determined by a visual method and to assess the extent of agreement and bias among treadmill velocities for the lactate threshold as determined by visual (LTv) and polynomial (LTp) methods, glucose threshold as determined by visual (GTv) and polynomial (GTp) methods, and heart rate deflection point (HRdp) as a method for estimating the aerobic capacity of dogs. ANIMALS 18 healthy adult Beagles. PROCEDURES Each dog underwent a standardized incremental treadmill exercise test once. The test ended when the dog began to show signs of fatigue. Plasma lactate and glucose concentrations and heart rate (HR) were plotted against exercise intensity (treadmill velocity) for the duration of the test, and the LTv, GTv, and HRdp were determined visually. The LTp and GTp were determined by means of a second-order polynomial function. One-way ANOVA, Pearson correlation, Bland-Altman analyses, and ordinary least products regression were used to assess the extent of agreement and bias among the various threshold velocities. RESULTS Mean velocity did not differ significantly among the thresholds evaluated. There was a strong positive correlation between the LTv velocity and the velocity for GTv (r = 0.91), LTp (r = 0.96), GTp (r = 0.94), and HRdp (r = 0.95). CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that LTv could be determined for dogs undergoing intense exercise on a treadmill, and the treadmill velocity corresponding to the LTv was associated with the velocity for the other hallmarks of endurance. Thus, that method may be useful for prescription and evaluation of conditioning programs for dogs.

OBJECTIVE To investigate the ability of a proprietary antagonist of E-type prostanoid receptor (EP) 4, grapiprant, and carprofen to attenuate lameness attributable to urate-induced synovitis in dogs. ANIMALS 5 purpose-bred hound-cross dogs. PROCEDURES A blinded, 3-way crossover study was performed. Dogs received each of 3 treatments (L-766, a proprietary antagonist of EP4; 4.0 mg/kg), grapiprant (an antagonist of EP4; 2.0 mg/kg), and carprofen (4.4 mg/kg); dogs received 4 doses of each treatment (14 and 2 hours before and 22 and 46 hours after urate injection). Synovitis was induced by intra-articular injection of sodium urate. Measurements (vertical ground reaction forces and clinical lameness scores) were obtained immediately before (0 hours; baseline) and 6, 12, 24, 36, and 48 hours after sodium urate injection. All data were analyzed with repeated-measures ANOVA. RESULTS Lameness scores at 6 hours were significantly higher than baseline lameness scores for all treatments. Lameness scores for the grapiprant treatment remained significantly higher at 12 and 24 hours, compared with baseline lameness scores. Lameness scores for the carprofen treatment were significantly lower than lameness scores for the grapiprant treatment at 6, 12, and 24 hours. Analysis of peak vertical force and vertical impulse data revealed a pattern similar to that for lameness scores. Treatment with L-766 resulted in a significantly higher vertical impulse at 48 hours than did treatment with carprofen or grapiprant. CONCLUSIONS AND CLINICAL RELEVANCE In these dogs, carprofen was the most effective treatment for attenuating lameness induced by injection of sodium urate, and grapiprant was the least effective treatment.

The efficacy of 4 commercial porcine reproductive and respiratory syndrome virus (PRRSV) modified-live vaccines (MLV), against PRRSV-1 and PRRSV-2 was evaluated and compared in growing pigs. Two of the vaccines were based on PRRSV-1 and two on PRRSV-2. There were no significant differences between each of the two PRRSV-1 MLV vaccines and the two PRRSV-2 MLV vaccines respectively based on virology, immunological, and pathological evaluations. Vaccination with either of the PRRSV-1 MLV vaccines resulted in reduced PRRSV-1 but not PRRSV-2 viremia. Additionally, vaccination with either of the PRRSV-1 MLV vaccines resulted in reduction of lung lesions and PRRSV-1 positive cells in PRRSV-1 challenged pigs but had no significant effect in PRRSV-2 challenged pigs. In contrast, vaccination with either of the two PRRSV-2 MLV vaccines resulted in the reduction of both PRRSV-1 and PRRSV-2 viremia. The PRRSV-2 MLV vaccines were also able to effectively reduce lung lesions and PRRSV positive cells after challenge with either PRRSV-1 or PRRSV-2. Our data suggest that while vaccination with PRRSV-1 MLV vaccines can be effective against PRRSV-1, only PRRSV-2 MLV vaccines can protect against both Korean PRRSV-1 and PRRSV-2 challenges in this study.

OBJECTIVE To evaluate and report measurements of the radiographic cardiac silhouette of healthy juvenile and adult ospreys (Pandion haliaetus). ANIMALS 54 ospreys (22 adults, 19 juveniles, and 13 birds of undetermined age) without clinical signs of cardiac disease and with adequate ventrodorsal radiographic images for cardiac silhouette assessment. PROCEDURES Radiographs of ospreys were assessed to determine cardiac width at the widest point as well as sternal width and thoracic width at the same level. Two-way mixed-effects models were used to evaluate interrater reliability for mean rating. Multivariable linear regression analysis was used to create predictive models of cardiac width and to establish a theoretical reference range for healthy ospreys. RESULTS Cardiac width of healthy ospreys was approximately 90% to 92% of sternal width and 67% to 69% of thoracic width. Both sternal width and thoracic width were significant predictors of cardiac width in independent predictive models as well as in a combined model after controlling for age. Thirty-four of 41 (83%) measured cardiac widths were within the theoretical reference range. CONCLUSIONS AND CLINICAL RELEVANCE Ospreys are sentinels used in monitoring environmental health. Environmental factors may have an impact on the cardiac health of ospreys, but reference values for healthy ospreys have not been established for use in assessing cardiomegaly in this species. The radiographic ratios and predictive model obtained in this study may be useful for objective evaluation of cardiomegaly in ospreys.

The objectives of this study were to describe the frequency of antimicrobial resistance (AMR) in Escherichia coli and Campylobacter spp. isolates in fecal samples from beef cow-calf herds and to examine the associations between herd management practices, reported antimicrobial use, and AMR. Baseline prevalence data are needed to evaluate the effectiveness of antimicrobial stewardship programs. A pooled fecal sample, representing 20 cows, was collected from each of 107 herds during pregnancy testing. In the 305 recovered E. coli isolates (maximum 3 per herd), resistance to ≥ 1 antimicrobial was identified in 12 isolates [4%, 95% confidence interval (CI): 2% to 7%] from 105 herds (11%, 95% CI: 7% to 19%). The most common resistances identified in E. coli isolates were to tetracycline (3%) and to both streptomycin and sulfisoxazole (3%). Only 1 E. coli isolate was resistant to an antimicrobial of very high importance to human health - amoxicillin/clavulanic acid. However, 2 E. coli isolates had intermediate susceptibility to ciprofloxacin. Resistance to 1 antimicrobial was identified in 16 of 87 Campylobacter spp. isolates (18%, 95% CI: 11% to 28%) from 87 herds. Resistance to tetracycline was reported in 15% of Campylobacter spp. isolates and to nalidixic acid in 3.4%. Herds in which cows were treated with florfenicol were more likely to have E. coli resistance to ≥ 2 antimicrobials (OR 7.1, 95% CI: 1.1 to 57, P = 0.03). Herds with calf mortality of > 5% were more likely to have E. coli with resistance to streptomycin and sulfisoxazole [odds ratio (OR): 7.8, P = 0.03]. The results of this study are consistent with previous reports from western Canada and provide a starting point for designing an ongoing antimicrobial surveillance program.

OBJECTIVE To test the hypothesis that once-daily oral administration of atenolol would attenuate the heart rate response to isoproterenol for 24 hours. ANIMALS 20 healthy dogs. PROCEDURES A double-blind randomized placebo-controlled crossover study was conducted. Dogs were assigned to receive atenolol (1 mg/kg, PO, q 24 h) or a placebo for 5 to 7 days. After a washout period of 7 days, dogs then received the other treatment. Heart rate at rest (HRr) and heart rate induced by administration of isoproterenol (HRi) as a constant rate infusion (0.2 μg/kg/min for 5 to 7 minutes) were obtained by use of ECG 0, 0.25, 3, 6, 12, 18, and 24 hours after administration of the final dose of atenolol or the placebo. A mixed-model ANOVA was used to evaluate effects of treatment, time after drug or placebo administration, treatment-by-time interaction, period, and sequence on HRr and HRi. RESULTS Effects of sequence or period were not detected. There was a significant effect of treatment and the treatment-by-time interaction on HRi. Atenolol significantly attenuated HRi for 24 hours but did so maximally at 3 hours (least squares mean ± SE, 146 ± 5 beats/min and 208 ± 5 beats/min for atenolol and placebo, respectively). The effect at 24 hours was small (193 ± 5 beats/min and 206 ± 5 beats/min for atenolol and placebo, respectively). Atenolol had a small but significant effect on HRr. CONCLUSIONS AND CLINICAL RELEVANCE This study of healthy dogs receiving atenolol supported a recommendation for a dosing interval < 24 hours.

OBJECTIVE To evaluate use of flunixin meglumine as a treatment to postpone ovulation in mares, mare fertility after flunixin meglumine treatment during estrous cycles, and effects of flunixin meglumine on function of the corpus luteum after ovulation. ANIMALS 13 healthy mares. PROCEDURES A single-blinded, placebo-controlled, crossover study was conducted. Flunixin meglumine (1.1 mg/kg, IV, q 24 h) or lactated Ringer solution (placebo treatment) was administered for 2 days to mares with a dominant follicle (≥ 35 mm in diameter) and behavioral signs of estrus. Mares then were bred by artificial insemination. Number of days to ovulation from initial detection of a follicle ≥ 30 mm in diameter, uterine edema score, and pregnancy were determined by ultrasonography; the examiner was unaware of the treatment of each mare. Serum progesterone concentrations were evaluated 5 and 12 days after ovulation by use of radioimmunoassay. RESULTS Data were available for 45 estrus cycles of the 13 mares. Number of days to ovulation from initial detection of a follicle ≥ 30 mm was not significantly affected by administration of flunixin meglumine versus the placebo. Per-cycle pregnancy rate was not significantly different between flunixin meglumine (20/24 [83%] breedings) and the placebo (13/19 [68%] breedings). Flunixin meglumine did not significantly affect behavioral signs of estrus, uterine edema, or serum progesterone concentrations. CONCLUSIONS AND CLINICAL RELEVANCE Findings did not support the use of flunixin meglumine to postpone ovulation in mares.

This study evaluated the effects of 3 morphine doses combined with acepromazine, on sedation and physiological parameters in 5 clinically healthy dogs. Four treatments were administered intramuscularly in a randomized, blinded, crossover design: acepromazine, 0.05 mg/kg, alone (ACP) and acepromazine plus morphine at doses of 0.25, 0.5, and 1.0 mg/kg body weight (BW) (AM(0.25), AM(0.5), and AM(1.0), respectively). Sedation scores and cardiorespiratory variables were evaluated for 120 min after drug administration. The sedation scores were significantly higher with the AM(0.25) and AM(1.0) treatments than with the ACP treatment. At 30 min the scores were 36% to 66% higher with AM(1.0) than with AM0.25 and AM0.5, respectively, but these differences were not significant. The physiological variables remained acceptable for dogs. The results of this study do not support the use of AM0.5 over AM(0.25) to improve sedation in dogs, but they do indicate that sedation may be greater with AM(1.0) than with AM(0.25) and AM(0.5). Studies with a greater number of samples are warranted to confirm this statement.

OBJECTIVE To assess liver and spleen stiffness in healthy dogs by use of a novel 2-D shear wave elastography (SWE) technique and to investigate the repeatability and reproducibility of the technique. ANIMALS 8 healthy adult Beagles. PROCEDURES 2-D SWE was performed on each dog to assess liver and spleen stiffness. Repeatability (intraday variability) and reproducibility (interday variability) of 2-D SWE were investigated. For all 8 dogs, 2-D SWE was performed 3 times in 1 day (4-hour intervals) and on 3 separate days (1-week interval). Data were expressed as mean ± SD values for shear wave velocity and the Young modulus in the liver and spleen. Intraday and interday coefficients of variation were assessed for all variables. RESULTS Mean ± SD shear wave velocity obtained for the liver and spleen was 1.51 ± 0.08 m/s and 2.18 ± 0.27 m/s, respectively. Mean value for the Young modulus obtained for the liver and spleen was 6.93 ± 0.79 kPa and 14.66 ± 3.79 kPa, respectively. Elasticity values were significantly higher for the spleen than for the liver. Intraday and interday coefficients of variation for all variables were < 25% (range, 3.90% to 20.70%). CONCLUSIONS AND CLINICAL RELEVANCE 2-D SWE was a feasible technique for assessing liver and spleen stiffness of healthy dogs. Future studies on the application of 2-D SWE for dogs with chronic hepatitis, cirrhosis, and portal hypertension are needed to evaluate the clinical applicability of 2-D SWE.