Systemic therapy with oxytetracycline is often used for treatment of clinical metritis although data about its penetration into the uterus and uterine secretion are lacking. Uterine secretions and milk from six cows with clinical metritis were collected for microbiological assay. The animals were treated intramuscularly with long-acting oxytetracycline (20 mg/kg) and samples of plasma, milk and uterine secretions were collected for determination of the antibiotic concentrations by HPLC-PDA analysis. Pharmacokinetics of the antibiotic and in silico prediction of its penetration into the uterus were described. Trueperella pyogenes with MIC values of 16–64 µg mL⁻¹ was isolated (n of cows = 4) from uterine secretions. Oxytetracycline showed fast absorption and penetration in the uterine secretions and milk. No change of withdrawal time for milk was necessitated in cows with clinical metritis. Maximum levels in uterine secretions and predicted concentrations of oxytetracycline in the uterus were lower than MIC values. Systemic administration of long-acting oxytetracycline did not guarantee clinical cure and was not a suitable choice for treatment of clinical metritis associated with Trueperella pyogenes. The appropriate approach to antibiotic treatment of uterine infections of cows requires knowledge on penetration of the antibiotics at the site of infection and sensitivity of pathogens.

Puerperal metritis in cows is often treated with antibacterial drugs. The prudent use of antibiotics in farm animals requires state-of-the-art knowledge of their pharmacokinetics and data from sensitivity tests of pathogenic bacteria. Changes in oxytetracycline levels in the uterine secretion over time after intrauterine administration in cows with metritis were evaluated in relation to the sensitivity of pathogenic bacterial isolates. Oxytetracycline levels in plasma, milk and uterine secretion were determined via LC–MS/MS analysis. Pathogenic bacteria were isolated and their sensitivity to oxytetracycline was determined. The concentrations of oxytetracycline in the uterine secretion were 433.79 (39.17–1668.76) µg·mL⁻¹ six hours after the third application at a dose of 8 mg/kg and 84.33 (1.58–467.55) µg·mL⁻¹ 96 h after the last treatment. These levels were higher than the minimum inhibitory concentrations—namely, between 4 and 64 µg·mL⁻¹—against pathogenic isolates Trueperella pyogenes, Streptococcus intermedius, Escherichia coli and Bacillus pumilis. Higher concentrations over time were measured in milk rather than in plasma, indicating the need to monitor the withdrawal time for milk. The intrauterine infusion of oxytetracycline for three consecutive days resulted in the successful treatment of metritis in terms alleviating inflammation and restoring the estrus cycle in cows.

The aim of the present study was to determine the features and size of teat structures in cows using ultrasonography. The experiment was conducted with 12 clinically healthy Black-and-White cows, 3 years of age, with body weight of 350-450 kg. Ultrasonography was performed on 48 teats using ultrasound SonoScape A5v (SonoScape, China) with multifrequency linear transducer (5-12 MHz). The potential of the imaging technique to visualize teat structures as well as teat canal length and diameter, the diameter in the area of the Furstenberg’s rosette, teat wall thickness, teat cistern diameter in its middle part and teat cistern diameter in teat base was evaluated. Scans were conducted before milking, immediately after milking, and 1 and 2 hours after milking. The average teat canal length measured by ultrasound was 8.48±1.41 mm before milking, and until the 2nd post-milking hour its size became statistically significantly (p<0.001) lower (7.48±0.93 mm). Teat canal diameter showed a significant difference (p<0.01) only immediately after milking compared to the size before milking. The diameter of the middle part and the base of the teat cistern also tended to decrease considerably after milking (p<0.001) as compared to premilking values. The teat wall thickness immediately after milking and 1 hour after milking were statistically significantly higher (p<0.001) compared to the premilking size. The analysis of results showed that ultrasonography is a rapid non-invasive and accurate method for determination of characteristics and size of teat structures. It could be used for evaluation of changes occurring in bovine teat after milking - shortening of the teat canal, teat wall thickening and reduction of teat cistern diameter.