Viability of mammary bovine leukocytes challenged with anti-mastitis drugs

Abstract

The occurrence of viable cells in mammary gland secretions attests the functionality of the defense system. This fact, along with applied medicine, is fundamental for the healing udder. The objective of this study was to evaluate the in vitro viability of milk leukocytes challenged with four intramammary anti-mastitis drugs. We collected eight cow milk samples that were negative after a bacteriological examination. Cell suspensions were submitted to an evaluation of viability through Trypan Blue exclusion before and after incubation with the drugs. Mean pre-incubation viability rate (± standard deviation) of milk cells was 50.17% (± 6.50). Mean post-incubation viability rates (± standard deviation) of control group (devoid of any drug), Drug 1 (anhydrous cephalonium), Drug 2 (gentamicin), Drug 3 (procaine benzylpenicillin associated with dihydrostreptomycin nafcillin), and Drug 4 (benzathine cloxacillin) were, respectively, 31.36% (± 3.61); 26.23% (± 4.49); 7.82% (± 2.33); 3.10% (± 0.94); and 30.33% (± 4.14). The uppermost impairments were found when milk cells were challenged with Drug 2 and Drug 3. Although antimicrobial activity of tested drugs was not appraised, and a single aspect of cell function was tested, we concluded that treatments 2 and 3 could impair the functionality of milk leukocytes and could provide an ineffective immunological response, and an effective response is essential to control mammary infections.