A study to examine the relationship between uterine pathology and depletion of oxytetracycline in plasma and milk after intrauterine infusion

Citation: Gorden, P. J., Ydstie, J., Kleinhenz, M. D., Wulf, L. W., Gehring, R., Wang, C., & Coetzee, J. F. (2016). A study to examine the relationship between uterine pathology and depletion of oxytetracycline in plasma and milk after intrauterine infusion. Journal of Animal Science, 94, 30-30. doi:10.2527/msasas2016-065Metritis is a frequent problem in postpartum dairy cows. Intrauterine therapy with oxytetracycline (OTC) is often used to improve therapeutic outcomes, although efficacy data supporting this therapy are ambiguous. Several manuscripts describe the depletion of OTC from milk following intrauterine therapy. However, none of these studies have correlated uterine severity scores with milk OTC concentrations using highly sensitive detection systems. Our objective was to do this to test the hypothesis that cows with more severe uterine severity would have higher OTC residues in milk following intrauterine therapy. Thirty-two cows received a single treatment of 4 g of OTC via intrauterine infusion. Blood and milk samples were collected before intrauterine therapy and throughout the trial period of 96 h after infusion. Uterine severity scores were assigned at initiation of therapy and every 24 h throughout the remainder of the trial. Plasma and milk samples were analyzed for OTC concentrations using liquid chromatography coupled with mass spectrometry. Following treatment, OTC rapidly diffused from the uterus to plasma and from plasma to milk. Maximum concentration in plasma and milk occurred within 24 h following intrauterine infusion and 18 of the cows still had detectable levels of OTC in milk 4 d after intrauterine infusion. Greater uterine severity score at the initiation of treatment showed a significant positively correlation with higher milk OTC concentration at the second milking following treatment (R2 = 0.46, P = 0.01) but there was no correlation between initial uterine severity score and OTC concentration at the conclusion of the study (R2 = ?0.06, P = 0.75). In the United States, intrauterine administration of OTC is considered to be an extra-label therapy. The use of uterine severity score can be used to predict OTC concentration in the first day following therapy but should not be used as a predictor of OTC concentrations 96 h after treatment. Dairy producers should consult with their veterinarian to develop strategies that will prevent the presence of violative residues of OTC in bulk tank milk following intrauterine therapy

Geometric Construction of Mixed Potentials

This paper presents an approach to construct mixed potentials, to be used as storage functions in the context of dissipative systems theory. The objective is to obtain, through a locally-defined geometric decomposition of a given drift vector field, a potential similar to the thermodynamically-defined availability function proposed in the literature. The mixed potential is obtained by homotopy integration of a differential one-form for the drift vector field which decomposes the system into an exact part (generated by a potential) and an anti-exact part (which is not directly generated by a potential). The key element in the proposed approach is the computation of an integrating factor for the anti-exact part of the dynamics

Comparison of milk and plasma pharmacokinetics of meloxicam in postpartum versus mid-lactation Holstein cows

The objective of this study reported here was determine whether differences occurred in meloxicam pharmacokinetics between postpartum cows and mid-lactation cows. Preliminary data from a separate study (P. J. Gorden, unpublished data) in postpartum cows demonstrated elevated plasma and milk concentration profiles compared to previously published data (Malreddy, Coetzee, KuKanich, & Gehring, ). Two different groups were enrolled, each with 10 cows. The treatment group (TRT) was postpartum cows treated with meloxicam, and the positive control (PC) group was cows in mid-lactation treated with meloxicam. Plasma and milk meloxicam concentrations between the TRT and PC group were compared. Significant differences in meloxicam concentration in plasma were determined at all time points from 8 hr to 120 hr post-treatment. In milk, there was a treatment (p = .003), time (p < .001), and treatment by time interaction (p < .001). Significant differences in milk meloxicam concentration were determined at all time points from 8 hr to 96 hr post-treatment, except for the 16-hr time point. The time needed for meloxicam to no longer be detected in milk of the TRT group was longer compared to the PC group, indicating that a longer milk withdrawal is needed. These data suggest higher bioavailability as the underlying mechanism. Further research is needed to determine the mechanisms underlying differences this outcome

Comparison of milk and plasma pharmacokinetics of meloxicam in postpartum versus mid-lactation Holstein cows

The objective of this study reported here was determine whether differences occurred in meloxicam pharmacokinetics between postpartum cows and mid-lactation cows. Preliminary data from a separate study (P. J. Gorden, unpublished data) in postpartum cows demonstrated elevated plasma and milk concentration profiles compared to previously published data (Malreddy, Coetzee, KuKanich, & Gehring, ). Two different groups were enrolled, each with 10 cows. The treatment group (TRT) was postpartum cows treated with meloxicam, and the positive control (PC) group was cows in mid-lactation treated with meloxicam. Plasma and milk meloxicam concentrations between the TRT and PC group were compared. Significant differences in meloxicam concentration in plasma were determined at all time points from 8 hr to 120 hr post-treatment. In milk, there was a treatment (p = .003), time (p < .001), and treatment by time interaction (p < .001). Significant differences in milk meloxicam concentration were determined at all time points from 8 hr to 96 hr post-treatment, except for the 16-hr time point. The time needed for meloxicam to no longer be detected in milk of the TRT group was longer compared to the PC group, indicating that a longer milk withdrawal is needed. These data suggest higher bioavailability as the underlying mechanism. Further research is needed to determine the mechanisms underlying differences this outcome