Introduction: The article presents a rapid and simple analytical procedure for determination of four tetracyclines (oxytetracycline, tetracycline, chlortetracycline, and doxycycline) in animal medicated feedingstuffs. Material and Methods: Two-gramme samples were extracted by a Na₂EDTA-McIlvaine buffer (pH 4)/methanol mixtures (40/60, v/v). The determination was achieved by liquid chromatography using a Zorbax Eclipse XDB C18 analytical column with mass spectrometer detection (LC-MS). Results: Recoveries of the antibiotics from spiked feed samples ranged from 78.2% to 113.5%. The LOD and LOQ for tetracyclines in feeds ranged from 2.8 to 4.2 and from 4.3 to 5.7 mg/kg, respectively. Conclusion: The method was successfully validated and proved to be efficient, precise, and useful for quantification of tetracyclines in medicated feedingstuffs.

Introduction: To identify novel pathways involved in the pathogenesis of ketosis, an isobaric tag for relative and absolute quantitation/mass spectrometry was used to define differences in protein expression profiles between healthy dairy cows and those with clinical or subclinical ketosis.Material and Methods: To define the novel pathways of ketosis in cattle, the differences in protein expression were analysed by bioinformatics. Go Ontology and Pathway analysis were carried out for enrich the role and pathway of the different expression proteins between healthy dairy cows and those with clinical or subclinical ketosis.Results: Differences were identified in 19 proteins, 16 of which were relatively up-regulated while the remaining 3 were relatively down-regulated. Sorbitol dehydrogenase (SORD) and glyceraldehyde-3-phosphate dehydrogenase (G3PD) were up-regulated in cattle with ketosis. SORD and G3PD promoted glycolysis. These mechanisms lead to pyruvic acid production increase and ketone body accumulation.Conclusion: The novel pathways of glycolysis provided new evidence for the research of ketosis.

Introduction: The objective of this study was to describe a pharmacokinetic–pharmacodynamic (PK/PD) approach for determination of a rational dosage of ampicillin (AMP) and depletion of the antibiotic residues in milk after intramammary administration to cows.Material and Methods: The cows came from different farms from the Lublin Province area. They (n = 9) received 5 g of the drug, containing 75 mg of AMP sodium in physiological solution, through a syringe tube by intramammary administration. Following single intramammary administration, the milk samples (5 mL) were collected after 2, 4, 6, 8, 10, 24, 36, 48, and 60 h. The liquid chromatography-mass spectrometry analysis was performed on the Agilent 1200 system connected to an AB Sciex API 4000™ mass spectrometer. The pharmacokinetic analysis of the concentrations of the antibiotic in milk was performed using software Phoenix® WinNonlin® 6.4. Calculations were made in non-compartmental (slopes, highest, amounts, and moments) and compartmental analysis.Results: The pharmacokinetic characteristics of AMP after intramammary administration indicate rapid elimination of the drug from milk. The mean residence time had a several-fold lower value than the designated elimination half-life and amounts to only 3.4 h. The concentration of the drug in the milk dropped relatively quickly and the process was very dynamic.Conclusion: The conducted research confirms the rationale of using the PK/PD model in order to verify the dosing regimen for other antibiotic groups and various indicators of the applied PK/PD model.

Introduction: The present study is a comprehensive overview of the natural occurrence of 17β-oestradiol and testosterone in serum of cattle in Poland. Material and Methods: The serum samples (n = 826) were collected from cattle within five years. The samples were examined for the presence of oestradiol and testosterone using ELISA or gas chromatography with mass spectrometry. Results: In 98 samples (24%) 17β-oestradiol was detected above decision limits of applied methods, including five samples over the recommended concentration of 0.1 μg L⁻¹. Of the serum samples taken from cows (≤18 months of age), 95 and 99 percentiles of the animals had 17β-oestradiol concentration below 0.027 and 0.086 μg L⁻¹ and of samples from cows over 18 months of age - below 0.059 and 0.125 μg L⁻¹ respectively. Calculated values for bulls (≤18 months of age) were 0.025 and 0.034 μg L⁻¹ and for the animals older than 18 months of age - 0.035 and 0.041 μg L⁻¹. The natural presence of testosterone was detected in 201 serum samples (48.7%). According to the obtained data, 95% and 99% of cows (≤18 months of age) serum samples had testosterone concentration below 0.05 and 0.23 μg L⁻¹ and the animals over 18 months of age - 0.30 and 0.49 μg L⁻¹, respectively. For bulls these values did not depend on the age of the animals and were in the ranges of 5 - 6.3 μg L⁻¹ (95%) and 11.4 - 12.1 μg L⁻¹ (99%). Conclusion: Our study showed that the threshold values for these hormones in plasma of cattle designated years ago are correct, but they need to be supplemented for animals older than 18 months.

Introduction: The differentially expressed proteins between healthy cows and those with footrot were identified to explore changes in protein profiles associated with the disease. Material and Methods: Out of 36 cows selected for the experiment, 18 footrot-affected cows were included in the treatment group (group T) and 18 unaffected cows were included in the control group (group C). Plasma samples from groups T and C were subjected to two-dimensional electrophoresis analysis and differentially expressed proteins were identified by matrix-assisted laser desorption/ionisation tandem time-of-flight mass spectrometry. Bioinformatics, including gene ontology analysis and pathway analysis, was used for analysing all proteins. Results: Out of 63 spots identified by 2DE, 33 were selected for mass spectrum analysis, which identified 11 differentially expressed proteins in 26 spots. Footrot led to changes in profiles in plasma proteins that were classified to the pathway of inflammatory response, complement, and blood coagulation, among others. Conclusion: This study provides evidence of the defence mechanisms of cows with footrot to explore strategies for treatment.

OBJECTIVE To determine the pharmacokinetics of detomidine hydrochloride administered IV (as an injectable formulation) or by the oral-transmucosal (OTM) route (as a gel) and assess sedative effects of the OTM treatment in healthy dogs. ANIMALS 12 healthy adult dogs.PROCEDURES In phase 1, detomidine was administered by IV (0.5 mg/m2) or OTM (1 mg/m2) routes to 6 dogs. After a 24-hour washout period, each dog received the alternate treatment. Blood samples were collected for quantification via liquid chromatography with mass spectrometry and pharmacokinetic analysis. In phase 2, 6 dogs received dexmedetomidine IV (0.125 mg/m2) or detomidine gel by OTM administration (0.5 mg/m2), and sedation was measured by a blinded observer using 2 standardized sedation scales while dogs underwent jugular catheter placement. After a l-week washout period, each dog received the alternate treatment. RESULTS Median maximum concentration, time to maximum concentration, and bioavailability for detomidine gel following OTM administration were 7.03 ng/mL, 1.00 hour, and 34.52%, respectively; harmonic mean elimination half-life was 0.63 hours. All dogs were sedated and became laterally recumbent with phase 1 treatments. In phase 2, median global sedation score following OTM administration of detomidine gel was significantly lower (indicating a lesser degree of sedation) than that following IV dexmedetomidine treatment; however, total sedation score during jugular vein catheterization did not differ between treatments. The gel was subjectively easy to administer, and systemic absorption was sufficient for sedation. CONCLUSIONS AND CLINICAL RELEVANCE Detomidine gel administered by the OTM route provided sedation suitable for a short, minimally invasive procedure in healthy dogs.

The objective of this study was to evaluate the stability of 3 distinct preparations of ketamine and xylazine, with or without acepromazine, stored at room temperature or at 4°C for 1, 2, and 3 mo. Drug concentrations were compared to fresh solutions, using a high performance liquid chromatography-mass spectrometry/selected-ion monitoring (HPLC-MS/SIM) assay. The concentrations of ketamine and xylazine, diluted in physiological saline, did not change over time at room temperature or at 4°C. However, acepromazine concentrations decreased over time when stored at room temperature. In contrast, undiluted ketamine-xylazine preparations gradually decreased in concentration when stored at room temperature. All of the drug concentrations remained above 90% of their original concentration when stored at 4°C. In conclusion, when diluted in physiological saline, ketamine-xylazine cocktails can be stored for 3 mo, whereas undiluted cocktails can lose efficacy over 3 mo at room temperature. Storage at 4°C could preserve drug stability.

OBJECTIVE To determine pharmacodynamic and pharmacokinetic profiles of aminocaproic acid (ACA) by use of a thromboelastography (TEG)-based in vitro model of hyperfibrinolysis and high-performance liquid chromatography–mass spectrometry. ANIMALS 5 healthy adult dogs. PROCEDURES A single dose of injectable ACA (20, 50, or 100 mg/kg) or an ACA tablet (approximately 100 mg/kg) was administered orally. Blood samples were collected at 0, 15, 30, 45, 60, 90, 120, and 240 minutes after ACA administration for pharmacokinetic analysis. Samples were obtained at 0, 60, and 240 minutes for pharmacodynamic analysis by use of a TEG model of hyperfibrinolysis. RESULTS No adverse effects were detected. In the hyperfibrinolysis model, after all doses, a significantly higher TEG maximum amplitude (clot strength), compared with baseline, was detected at 60 and 240 minutes. Additionally, the percentage of fibrinolysis was reduced from the baseline value at 60 and 240 minutes, with the greatest reduction at 60 minutes. At 240 minutes, there was significantly less fibrinolysis for the 100 mg/kg dose than the 20 mg/kg dose. Maximum plasma ACA concentration was dose dependent. There was no significant difference in pharmacokinetic parameters between 100 mg/kg formulations. CONCLUSIONS AND CLINICAL RELEVANCE In an in vitro model of hyperfibrinolysis, ACA inhibited fibrinolysis at all doses tested. At 240 minutes after administration, the 100 mg/kg dose inhibited fibrinolysis more effectively than did the 20 mg/kg dose. Thus, ACA may be useful for in vivo prevention of fibrinolysis in dogs. IMPACT FOR HUMAN MEDICINE These data may improve research models of hyperfibrinolytic diseases.

OBJECTIVE To determine serum and tissue concentrations of gallium (Ga) after oral administration of gallium nitrate (GaN) and gallium maltolate (GaM) to neonatal calves. ANIMALS 8 healthy neonatal calves. PROCEDURES Calves were assigned to 1 of 2 groups (4 calves/group). Gallium (50 mg/kg) was administered as GaN or GaM (equivalent to 13.15 mg of Ga/kg for GaN and 7.85 mg of Ga/kg for GaM) by oral gavage once daily for 5 days. Blood samples were collected 0, 0.25, 0.5, 1, 2, 4, 8, 12, and 24 hours after Ga administration on day 1; 4 and 24 hours after Ga administration on days 2, 3, and 4; and 4, 12, and 24 hours after Ga administration on day 5. On day 6, calves were euthanized and tissue samples were obtained. Serum and tissue Ga concentrations were measured by use of mass spectrometry. RESULTS Data were adjusted for total Ga dose, and comparisons were made between the 2 groups. Calves receiving GaM had a significantly higher dose-adjusted area under the curve and dose-adjusted maximum serum Ga concentration than did calves receiving GaN. Despite receiving less Ga per dose, calves receiving GaM had tissue Ga concentrations similar to those for calves receiving GaN. CONCLUSIONS AND CLINICAL RELEVANCE In this study, calves receiving GaM had significantly higher Ga absorption than did calves receiving GaN. These findings suggested that GaM might be useful as a prophylactic agent against Mycobacterium avium subsp paratuberculosis infection in neonatal calves.

OBJECTIVE To assess the pharmacokinetic properties of cefovecin in a cold-water teleost species. ANIMALS 10 healthy adult copper rockfish (Sebastes caurinus), sex unknown. PROCEDURES Cefovecin (16 mg/kg) was administered SC to the rockfish. Blood samples were collected at predetermined points for measurement of plasma cefovecin concentrations (3 samples/fish). Plasma cefovecin concentrations were measured via liquid chromatography with mass spectrometry. Pharmacokinetic analysis was performed by means of naïve pooled analysis and compartmental modeling. Plasma protein binding of cefovecin was determined by ultrafiltration. RESULTS Cefovecin administration appeared to be well tolerated by the rockfish. Pharmacokinetic analysis resulted in a maximum plasma concentration of 104.8 μg/mL at 2.07 hours after administration. Plasma terminal half-life was 32.5 hours, and area under the curve was 5,132 h·g/mL. Plasma protein binding was low (< 10%) for plasma concentrations of 10 and 100 μg of cefovecin/mL when assessed at 7.8° and 20°C. Plasma concentrations > 1 μg/mL persisted for the full 7-day follow-up period. CONCLUSIONS AND CLINICAL RELEVANCE SC administration of cefovecin to copper rockfish at a dose of 16 mg/kg yielded plasma concentrations > 1 μg/mL that persisted to 7 days, but some interindividual variability was observed. The low degree of plasma protein binding but high circulating concentration of free drug may allow an extended administration interval in rockfish. Studies are needed to assess the efficacy and safety of this dose in rockfish.