Pharmacokinetics of ceftiofur crystalline-free acid in plasma and seminal plasma in beef bulls.

The objective of this study was to compare the plasma (PL) and seminal plasma (SP) pharmacokinetic profile of ceftiofur (CEFT) and desuroylceftiofur acetamide (DFCA) after administration of CEFT crystalline-free acid (CCFA) by SC route in two sites of the ear in beef bulls. Four clinically healthy Hereford bulls received a comprehensive physical exam and subsequently a breeding-soundness examination, CBC, and chemistry profile panel. All bulls were diagnosed healthy and satisfactory potential breeders. In one group (n = 2), a single dose of CCFA was administered SC route at the base of the ear (BOE) at a dose of 6.6 mg/kg of body weight. The second group (n = 2) was also administered by SC route in the middle third of the posterior aspect of the ear (MTE). The concentrations of CEFT and DFCA in PL and SP were determined by a high-performance liquid chromatography mass spectrometry (HPLC-MS). Blood and semen samples were collected before the administration of CCFA and at 12, 24, 36, 48, 72, 96, 120, 144, and 168 h after injection. No levels of CEFT were detected in PL and only in 20 of the 40 SP samples (P = 0.0001). The mean level of CEFT in SP was 0.11 % in comparison with the DFCA level. DFCA was found in all PL and SP samples. Therefore, DFCA was chosen to be utilized in the study of the pharmacokinetics parameters both in PL and SP. There were no differences in the mean PL levels of DFCA for the two sites of SC administration between the BOE (102.9 ± 78.9 ng/mL; X ± SD) and to MTE (116.1 ± 70.2 ng/mL; P = 0.58). The mean SP levels of DFCA after administration in the BOE was 857 ± 747 ng/mL, and for the MTE was 549 ± 488 ng/mL without differences between both sites (P = 0.15). The mean level of DFCA in PL was 109.5 ± 74.0 ng/mL, which was lower than the mean SP levels of 695 ± 103 ng/mL (P = 0.001). Moreover, the PL peak DFCA concentration (Cmax) was 229 ± 46 ng/mL at 36.0 ± 29.4 h (Tmax) post-administration. The SP Cmax was 1851 ± 533 ng/mL at 30.0 ± 28.6 h (Tmax) post-administration. The Cmax between PL and SP were distinctive (P = 0.004) without any differences in Tmax between PL and SP (P = 0.60). The terminal half-life for PL DFCA (47.4 ± 29.3 h) was not different than in SP (53.1 ± 23.6 h; P = 0.77). The PL area under the curve concentration time from the first to the last sample (AUC0-last) was 18,984 ± 4841 ng/mL/h, which was significatively smaller compared with 125,677 ± 59,445 ng/mL/h for SP AUC0-last (P = 0.04). The PL mean residence time from the first to the last sample (MRT0-last) was 69.7 ± 15.1 h, and it was similar than for SP of 66.5 ± 7.7 h (P = 0.69). From the present investigation, based in its pharmacokinetic features, it was concluded that CCFA should be an appropriate antibiotic that could be used for the treatment of bull genital infections when its indication is properly outlined. To study the pharmacokinetics of CCFA in SP, DFCA metabolite was appropriated.

Pharmacokinetics of oxytetracycline long-acting on plasma and semen of beef bulls.

The objectives of this investigation were to evaluate the pharmacokinetic parameters of oxytetracycline long-acting in plasma and seminal plasma after a single administration through either subcutaneous or intramuscular route at 10 mg/kg or 20 mg/kg dose. Four Simmental bulls, healthy and satisfactory potential breeders, were used. The route of administration either subcutaneous or intramuscular did not affect the mean values for 10 mg/kg dose in plasma (1,470 ng/mL vs. 1,330 ng/mL; P = 0.82) or seminal plasma (5,710 ng/mL vs. 5,390 ng/mL; P = 0.88), or for 20 mg/kg dose in plasma (2,540 ng/mL vs. 2,590 ng/mL; P = 0.96) or seminal plasma (25,600 ng/mL vs. 19,400 ng/mL; P = 0.58), respectively. Comparison between the 10 mg/kg and 20 mg/kg doses showed a difference in terms of mean plasma levels (1400 ng/mL vs. 2570 ng/mL; P = 0.07) and mean seminal plasma levels (6,480 ng/mL vs. 26,200 ng/mL; P = 0.004), respectively. After the dose of 10 mg/kg, plasma Cmax was 2,841 ng/mL at 12 h (Tmax) with a half-life of 20.1 h; seminal plasma Cmax was 11,515 ng/mL at 24 h (Tmax) with a half-life of 23.7 h. After the dose of 20 mg/kg, plasma Cmax was 5,269 ng/mL at 12 h (Tmax) with a half-life of 18.1 h; seminal plasma Cmax was 55,040 ng/mL at 24 h (Tmax) with a half-life of 15.7 h. Oxytetracycline long-acting may be an appropriate antibiotic, owing to its pharmacokinetic properties, that could be used for treating bulls' genital infections when its usage is indicated.

Pharmacokinetics of tulathromycin on plasma and semen of beef bulls.

The objective of this investigation was to evaluate the pharmacokinetic parameters of tulathromycin in plasma and semen of beef bulls after administering a single sc dose at two different sites in the neck. Four Simmental bulls with excellent temperament received a comprehensive physical exam that included breeding soundness examination. In addition, blood was collected and analyzed for CBC and chemical panel in order to rule out any subclinical liver or kidney disease. All bulls were diagnosed as healthy and satisfactory potential breeders. The mean plasma levels of tulathromycin for the two neck sites of sc administration were not different between posterior aspect of the ear where it attaches to the head (RP; regio parotidea; 77.9 ± 43.3 ng/mL; X ± SD) and to the middle of the neck (RC; regio collis lateralis; 73.7 ± 39.7 ng/mL; P = 0.84). The mean seminal plasma levels of tulathromycin after administration in the RP was 608 ± 374 ng/mL and for RC was 867 ± 599 ng/mL without differences between both sites (P = 0.29). The mean level of tulathromycin in plasma was 75.8 ± 40.2 ng/mL, which was lower than mean seminal plasma levels of 781 ± 482 ng/mL (P = 0.001). The plasma peak tulathromycin concentration (Cmax) was 160 ± 27 ng/mL at 21 ± 6 h (Tmax) post-administration. The seminal plasma Cmax was 1539 ± 44.4 ng/mL at 33.00 ± 18.00 h (Tmax) post-administration. The Cmax between plasma and seminal plasma were different (P = 0.008) without any differences in Tmax between plasma and seminal plasma (P = 0.35). The terminal half-life for plasma tulathromycin (81.4 ± 27.6 h) showed a tendency to be shorter than in seminal plasma (114.7 ± 21.7; P = 0.10). The plasma area under the curve concentration time from the first to the last sample (AUC0-last) was 15,440 ± 1717 ng/mL/h, which was significatively smaller compared with 171,071 ± 58,556 ng/mL/h for seminal plasma AUC0-last (P = 0.01). The plasma means residence time from the first to the last sample (MRT0-last) was 89.3 ± 5.1 h and it was shorter than for seminal plasma of 96.6 ± 5.0 h (P = 0.05). From the present investigation, it was concluded that tulathromycin is a suitable antibiotic based in its pharmacokinetic properties that could be used for treatment of bull genital infections when its application is indicated.

Non-mosaic monosomy 59,X in cattle: a case report.

A 3-year-old Longhorn heifer was referred to the Veterinary Medical Teaching Hospital of Texas A&M University for inability to get pregnant. Physical examination revealed a small-sized female for age and breed with a normal vulva, vaginal length, and external cervical os. Further assessment by per rectum palpation and trans-rectal ultrasonography revealed a small uterine cervix and cord-like uterine horns with no identifiable ovaries. Additional evaluation including laparoscopy, hormonal evaluation, and genetic analysis allowed ruling out conditions commonly associated with a phenotypic female with infantile or underdeveloped reproductive organs such as freemartin, XY gonadal dysgenesis, testicular feminization, and bilateral ovarian agenesis. Laparoscopy confirmed the presence of a small cervix with small uterine horns and absence of ovaries. Testosterone, progesterone, and 17-ß estradiol concentrations were 200.0pg/mL, 1.48ng/mL, and undetectable, respectively. Genetic evaluation determined that the karyotype was 59,X non-mosaic. Evaluation of phenotypically female cattle with infertility and infantile genital organs and absence of ovaries should include cytogenetic analysis to test for possible X monosomy. The 59,X condition should be considered in the differential diagnoses together with freemartin, dysgenesis XY, testicular feminization, and bilateral ovarian agenesis.