Plant foliages used as feed additives pose a health risk due to high oxidant concentrations. Oxidants cause oxidative stress and high rate of morbidities and mortalities. Hence, the aim of the study was to validate the methods to quantify gallic acid (GA) and quercetin (Q) as putative antioxidants, and to evaluate antioxidant activities in feed (F), Hyperacanthus amoenus (HA) and Carissa bispinosa (CB) extracts. Extraction was carried out with 62.5% methanol. Method validations for linearity, accuracy and precision were performed on high performance liquid chromatography. Quantitative analysis of GA and Q and testing of 2,2-diphenyl-2-picrylhydrazyl (DPPH) scavenging activities in the extracts were performed. The lowest limit of detection (LOD) and limit of quantitation (LOQ) of 0.011 µg/mL and 0.032 µg/mL were determined in HA, respectively. The methods were accurate and precise as the relative standard deviations (%RSD) were less than 15%. The GA concentrations in CB and HA extracts were statistically significant (p  0.05) and their values were 0.65 ± 0.03 x 106 µg/kg dry weight (DW) (0.13%) and 0.28 ± 0.06 x 106 µg/kg DW (0.002%), respectively. All extracts showed very strong radical scavenging activities with their IC50 values ranging between 5.87 µg/mL and 6.86 µg/mL. Contribution: These accurate, repeatable, precise and reliable methods can be used to provide a valuable basis for GA and Q analysis in various shrub foliages. Though high GA concentrations have potential to act as antioxidants, they may have adverse health and growth performance effects when used as feed additives, while lower Q concentrations may have no effects on livestock.

OBJECTIVE To determine the pharmacokinetics of enrofloxacin after IV administration in American black vultures (Coragyps atratus), to compare clearance of enrofloxacin in American black vultures with clearance of this fluoroquinolone in other avian species, and to evaluate whether allometric scaling is an appropriate tool for dose extrapolation in avian species. ANIMALS 6 healthy adult American black vultures. PROCEDURES Enrofloxacin concentrations were quantified by use of high-performance liquid chromatography. Pharmacokinetics of enrofloxacin was determined in American black vultures after IV administration. Pharmacokinetic parameters for 12 avian species obtained from 24 pharmacokinetic studies were used. Allometric analysis of enrofloxacin pharmacokinetic parameters was performed. RESULTS Volume of distribution at steady state for enrofloxacin was 3.47 L/kg, clearance was 0.147 L/h·kg, and elimination half-life was 18.3 hours. Comparisons among avian species revealed that American black vultures had the lowest extraction ratio for enrofloxacin (1.04%). Only the volume of distribution at steady state and clearance had a good allometric fit. Goodness of fit was improved when ratites were not included in the analysis. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that the use of allometric scaling for the prediction of volume of distribution at steady state could provide a suitable method for extrapolation of enrofloxacin doses among avian species; however, allometric scaling could not be used to adequately predict the clearance of enrofloxacin.

OBJECTIVE To evaluate glomerular filtration rate (GFR) estimation by means of plasma clearance of iohexol (IOX) in domestic rabbits and to assess accuracy of limited-sampling models for GFR estimation. ANIMALS 6 healthy domestic rabbits (Oryctolagus cuniculus). PROCEDURES Each rabbit received IOX (64.7 mg/kg [0.1 mL/kg], IV), and blood samples were collected at predetermined times before and after administration. Plasma IOX concentration was determined by high-performance liquid chromatography. The pharmacokinetics of IOX was determined by a noncompartmental method. For each rabbit, plasma clearance of IOX was determined by dividing the total IOX dose administered by the area under the concentration-time curve indexed to the subject's body weight. The GFR estimated from the plasma IOX concentration at 6 sampling times (referent model) was compared with that estimated from the plasma IOX concentration at 5 (model A), 4 (model B), and 3 (models C, D, and E) sampling times (limited-sampling models). RESULTS Mean ± SD GFR was 4.41 ± 1.10 mL/min/kg for the referent model and did not differ significantly from the GFR estimated by any of the limited-sampling models. The GFR bias magnitude relative to the referent model was smallest for model D in which GFR was estimated from plasma IOX concentrations at 5, 15, and 90 minutes after IOX administration. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that plasma clearance of IOX was a safe, reliable, accurate, and clinically feasible method to estimate GFR in domestic rabbits. Further research is necessary to refine the method.

OBJECTIVE To compare the pharmacokinetics of 2 commercial florfenicol formulations following IM and SC administration to sheep. ANIMALS 16 healthy adult mixed-breed sheep. PROCEDURES In a crossover study, sheep were randomly assigned to receive florfenicol formulation A or B at a single dose of 20 mg/kg, IM, or 40 mg/kg, SC. After a 2-week washout period, each sheep was administered the opposite formulation at the same dose and administration route as the initial formulation. Blood samples were collected immediately before and at predetermined times for 24 hours after each florfenicol administration. Plasma florfenicol concentrations were determined by high-performance liquid chromatography. Pharmacokinetic parameters were estimated by noncompartmental methods and compared between the 2 formulations at each dose and route of administration. RESULTS Median maximum plasma concentration, elimination half-life, and area under the concentration-time curve from time 0 to the last quantifiable measurement for florfenicol were 3.76 μg/mL, 13.44 hours, and 24.88 μg•h/mL, respectively, for formulation A and 7.72 μg/mL, 5.98 hours, and 41.53 μg•h/mL, respectively, for formulation B following administration of 20 mg of florfenicol/kg, IM, and 2.63 μg/mL, 12.48 hours, and 31.63 μg•h/mL, respectively, for formulation A and 4.70 μg/mL, 16.60 hours, and 48.32 μg•h/mL, respectively, for formulation B following administration of 40 mg of florfenicol/kg, SC. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that both formulations achieved plasma florfenicol concentrations expected to be therapeutic for respiratory tract disease caused by Mannheimia haemolytica or Pasteurella spp at both doses and administration routes evaluated.

This study was undertaken to develop new analytical methods for assessment of anticoccidials. Highperformance liquid chromatography (HPLC) was found to be a fast, reliable, and practical method. The anticoccidials used in this experiment were toltrazuril and diclazuril, and the analysis factors were specificity, linearity, accuracy, repeatability, and intermediate precision. The linearity of each anticoccidial was better than 0.99, and the accuracies were 99.5% and 99.1% with relative SD of 0.5 and 0.4, respectively. To assess whether the developed HPLC method could be effectively applied, toltrazuril and diclazuril post-market veterinary products (five products) that are currently sold were tested. The results revealed no non-compliant items and the method was applied successfully. Therefore, the newly developed HPLC method for anticoccidial assessment described in this study may be useful as a reference method in the Korean Standards of Veterinary Pharmaceuticals for the analysis of toltrazuril and diclazuril.