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    Pharmacokinetics and effect on renal function and average daily gain in lambs after castration and tail docking, of firocoxib and meloxicam.
    (Taylor and Francis Group, 2023-07-16) Kongara K; Purchas G; Dukkipati V; Venkatachalam D; Ward N; Hunt H; Speed D
    AIMS: To evaluate and compare the pharmacokinetics of IM and oral firocoxib, and IM meloxicam, and detect their effect on renal function and average daily gain (ADG) in lambs undergoing tail docking and castration. METHODS: Seventy-five male Romney lambs, aged 3-6 weeks, were randomised into five treatment groups (n = 15 per group): IM firocoxib (1 mg/kg); oral firocoxib (1 mg/kg); IM meloxicam (1 mg/kg); normal saline (approximately 2 mL, oral); or sham. Following the treatment administration, hot-iron tail docking and rubber ring castration were performed in all groups except the sham group, which did not undergo the procedures, but the animals were handled in the same manner as castrated and tail docked lambs. Blood samples were collected before and 1, 2, 4, 6, 8, 24, 48, 72, 96 and 120 hours after treatment administration, and drug concentrations in plasma were quantified by liquid chromatography and mass spectrometry. Plasma urea and creatinine concentrations were determined at a commercial laboratory. Lamb body weights were recorded before and 2, 4 and 8 weeks after tail docking and castration. The pharmacokinetic analysis was carried out using a non-compartmental approach. Between-group and between-time-point differences were compared using mixed model analyses. RESULTS: There was no evidence for a difference in plasma elimination half-life between firocoxib given IM (LSM 18.6 (SE 1.4) hours), firocoxib given orally (LSM 18.2 (SE 1.4) hours), and meloxicam given IM (LSM 17. 0 (SE 1.4) hours). Firocoxib (IM) had a significantly greater volume of distribution (LSM 3.7 (SE 0.2) L/kg) than IM meloxicam (LSM 0.2 (SE 0.2) L/kg). Lambs in the meloxicam group had higher (p < 0.05) plasma urea and creatinine concentrations than those in the firocoxib, saline and sham groups. Lambs' ADG was decreased (p < 0.01) compared to the other treatment groups in the 0-2 week period following meloxicam administration. CONCLUSIONS AND CLINICAL RELEVANCE: Both formulations of firocoxib had a long plasma elimination half-life and large volume of distribution. There was a transient reduction in ADG in the meloxicam group, possibly due to mild renal toxicity. Comparative studies on dose-response effects of firocoxib and meloxicam in lambs following the procedures are required.
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    Biochemical profile of heifers with spontaneous humeral fractures suggest that protein-energy malnutrition could be an important factor in the pathology of this disease.
    (2023-01) Wehrle-Martinez A; Dittmer KE; Back PJ; Rogers CW; Lawrence K
    CASE HISTORY: Serum and liver samples from 35, 2-year-old dairy heifers that had fractured one or both humeri post-calving between July and December 2019 were submitted to a diagnostic laboratory for analysis. Serum samples were analysed for albumin, β-hydroxybutyrate (BHB), creatinine, Ca, Mg, phosphate, non-esterified fatty acids (NEFA), and serum Cu concentration. Liver samples were analysed for liver Cu concentration. Data were compared to published reference intervals. Data values for heifers that prior to fracture had grazed fodder beet were also compared to values for those that had grazed pasture. CLINICAL FINDINGS: Sixty-nine percent of heifers with humeral fracture had serum creatinine concentrations below the lower value of the reference range (55-130 µmol/L). In 3/32 (9%) heifers, serum NEFA concentrations were increased above the reference value indicating body fat mobilisation (≥1.2 mmol/L for peri-partum cows) and in 20/35 (57%) heifers BHB serum concentrations were above the reference value indicating subclinical ketosis (≥1.1 mmol/L for peri-partum cows). In 24/35 (69%) heifers, liver Cu concentration was low (≤ 44 µmol/kg) or marginal (45-94 µmol/kg). The concentration of Cu in serum was low (≤ 4.5 µmol/L) in 2/33 (6%) heifers and marginal (4.6-7.9 µmol/L) in 5/33 (15%) heifers. There was moderate positive correlation between the logged concentrations of Cu in paired liver and serum samples, r(31) = 0.43; (95% CI = 0.1-0.79; p = 0.014). One heifer had a serum phosphate concentration below the lower limit of the reference range (< 1.10 mmol/L). For all heifers, the concentrations of albumin, Ca, and Mg in serum were within the reference intervals (23-38 g/L, 2.00-2.60 mmol/L, and 0.49-1.15 mmol/L respectively). Over winter, 15/35 (43%) heifers grazed predominantly pasture, 14/35 (40%) grazed fodder beet and 6/35 (17%) had a mixed diet. CLINICAL RELEVANCE: In some of these heifers with humeral fractures, there was evidence for protein and/or energy malnutrition in the form of elevated NEFA and BHB concentrations and low creatinine concentrations in serum. Liver Cu concentrations were also reduced in most affected heifers. However, the absence of a control group means it is not possible to determine if these are risk factors for fracture or features common to all periparturient heifers. Clinical trials and molecular studies are needed to determine the true contribution of Cu and protein-energy metabolism to the pathogenesis of spontaneous humeral fractures in dairy heifers. ABBREVIATIONS: BHB: ß-hydroxybutyrate; NEFA: Non-esterified fatty acids.
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    Determination of creatinine and creatine by capillary electrophoresis : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Chemistry at Massey University
    (Massey University, 1998) Guo, Hong
    The assessment of creatinine and creatine in biological fluids is important in the evaluation of renal and muscular functions. For routine creatinine determinations in the clinical laboratory, the most frequently used method is the spectrophotometric one based on the Jaffé reaction. However, this reaction is not specific for creatinine. For this reason, several methods have been proposed, but the elimination of interferences in the determination of creatinine has still not been achieved in some of these methods; others solved this problem either with expensive equipment that does not suit routine analysis or necessitates time-waste procedures. In this thesis capillary electrophoresis was the new tool investigated. It was applied in an attempt to achieve both the separation of creatinine from the non-creatinine 'Jaffé- reacting' chromogens and the determination of creatine in serum. Capillary zone electrophoresis was performed with detection at wavelength 480 nm to separate creatinine from the non-creatinine 'Jaffé-reacting' chromogens in urine. The principle was based upon the different migration times due to the different molecule weights, molecular sizes and charges under the applied high voltage. The picric acid was employed as part of the running buffer to allow reaction of creatinine and picrate to take place after the sample injection. This procedure eliminated the negative influence of the reaction time that is controlled manually in the common Jaffé reaction method. Therefore, compared to the Jaffé reaction method, the new method achieved more accuracy and precision in the determination of creatinine. Determination of creatinine in serum and urine were studied at a new wavelength 417 nm, which gave a higher sensitivity of detection than at 480 nm. This wavelength shift made the determination of creatinine in serum possible by capillary zone electrophoresis without the non-creatinine 'Jaffé-reacting' chromogens interfering. In this method, serum only needed a simple filtration before the analysis. Creatine was discovered to have absorption at 417 nm in alkaline medium. Moreover, specific sample stacking was introduced in this method. The sample was dissolved in a mixture of two-volumes acetonitrile and one-volume 3 % ammonium chloride to give a 10-fold enhancement of detection sensitivity.
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    Assessment of the effect of blood contamination on the urinary protein to creatinine ratio in the dog : a dissertation presented in partial fulfilment of the requirements for the degree of Master of Veterinary Studies in Veterinary Pathology at Massey University, College of Science, Turitea, Palmerston North, New Zealand
    (Massey University, 2007) Jillings, Eloise Katherine Puia
    The urine protein to creatinine ratio (UPCR) is a reliable method to assess the total urinary protein loss in the dog from a single urine sample. Interpretation of the urine protein to creatinine ratio has been difficult in the presence of haematuria in the sample and previously the presence of blood in the urine has negated the use or interpretation of the UPCR. In 2 previous studies blood has been added to the urine sample of a single dog to aid interpretation of the UPCR in the presence of blood contamination. In this study blood contamination of urine samples in 21 dogs was assessed to develop guidelines for interpretation of the UPCR in the face of haemorrhage. Blood was added to the urine from the same dog to make samples with blood contamination levels ranging from 0 to 5%. Urine dipstick analysis, microscopic examination and a UPCR was performed on all samples. The current recommended cut off level for UPCR for normal dogs is <0.5. Results greater than 1.0 are considered abnormal, results greater than 2.0 suggests glomerular disease, and UPCR results between 0.5 and 1.0 are questionable. The results of the present study suggest that when urine is visibly red, haemorrhage may be considered as a differential for a UPCR up to 2.0. The practice of attributing proteinuria in non discoloured (yellow) urine samples with microscopic haemorrhage to the blood present should be discontinued, as microscopic haemorrhage that does not result in a visible change in colour of the urine sample from yellow will not substantially increase the UPCR. As such, the UPCR level in yellow urine even in the presence of microscopic haematuria can be considered valid.