As warned by Sir Alexander Fleming in his Nobel Prize address: “the use of antimicrobials can, and will, lead to resistance”. Antimicrobial resistance (AMR) has recently increased due to the overuse and misuse of antibiotics, and their use in animals (food-producing and companion) has also resulted in the selection and transmission of resistant bacteria. The epidemiology of resistance is complex, and factors other than the overall quantity of antibiotics consumed may influence it. Nowadays, AMR has a serious impact on society, both economically and in terms of healthcare. This narrative review aimed to provide a scenario of the state of the AMR phenomenon in veterinary medicine related to the use of antibiotics in different animal species; the impact that it can have on animals, as well as humans and the environment, was considered. Providing some particular instances, the authors tried to explain the vastness of the phenomenon of AMR in veterinary medicine due to many and diverse aspects that cannot always be controlled. The veterinarian is the main reference point here and has a high responsibility towards the human–animal–environment triad. Sharing such a burden with human medicine and cooperating together for the same purpose (fighting and containing AMR) represents an effective example of the application of the One Health approach.

Bovine mastitis is a major concern for the dairy cattle community worldwide. Mastitis, subclinical or clinical, can be caused by contagious or environmental pathogens. Costs related to mastitis include direct and indirect losses, leading to global annual losses of USD 35 billion. The primary treatment of mastitis is represented by antibiotics, even if that results in the presence of residues in milk. The overuse and misuse of antibiotics in livestock is contributing to the development of antimicrobial resistance (AMR), resulting in a limited resolution of mastitis treatments, as well as a serious threat for public health. Novel alternatives, like the use of plant essential oils (EOs), are needed to replace antibiotic therapy when facing multidrug-resistant bacteria. This review aims to provide an updated overview of the in vitro and in vivo studies available on EOs and their main components as an antibacterial treatment against a variety of mastitis causing pathogens. There are many in vitro studies, but only several in vivo. Given the promising results of treatments with EOs, further clinical trials are needed.

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Florfenicol is a broad-spectrum antibiotic belonging to the amphenicols class that inhibits protein synthesis by binding to bacteria's ribosomal subunits. This drug is commonly used in veterinary medicine to treat bacterial infectious diseases in cattle, swine, poultry, and fish. The proposed method uses a quick protein precipitation with acetonitrile for the extraction of florfenicol and florfenicol amine in serum and seminal plasma, followed by analysis in UHPLC-MS/MS for their simultaneous quantification. A BEH C18 reversed-phase column was chosen for analyte separation, allowing to obtaining sharp and symmetrical peak shapes in a chromatographic run of just 3.5 min under programmed conditions. Two specific transitions were observed for each analyte, and florfenicol-d3 was used as the internal standard. The approach was fully validated in each matrix over ranges suitable for field concentrations of florfenicol and florfenicol amine, showing good linearity during each day of testing (R2 always >0.99). Excellent accuracy and precision were demonstrated, for both analytes, by calculated bias always within ±15% and CV% always below 15% at all QC levels tested. The satisfactory outcomes obtained during recovery, matrix effect, and process efficiency investigations in serum and seminal plasma confirmed the strength of the method for the quantification of target compounds. To our knowledge, this is the first LC-MS/MS-validated approach for the quantification of florfenicol and florfenicol amine in serum and seminal plasma and was successfully applied for the determination of their concentration-time profiles in bulls. This paves the way to understanding the pharmacokinetics of this antibiotic and its active metabolite in bull’s seminal plasma, which will enable the design of more appropriate treatment protocols.