Extended Therapy for Mastitis Control in Dairy Cows

Introduction: Extended therapy applied to mastitis treatment consists in treating cows for a longer period than labeled. The typical treatment of 1 to 3 days depending on the product is extended up to 8 consecutive days. Those treatments are mainly used to treat chronic subclinical mastitis caused by Staphylococcus aureus (S. aureus) or Streptococcus uberis (Str. uberis) but they can also be used to treat clinical mastitis. The objective of this presentation is to review the extended therapy principles and treatment regimens.Most antibiotics use for intramammary infusion treatment are time-dependent. This characteristic means that the efficacy of the antibiotic is proportional to the time of contact with the susceptible organism, as long as it is above an effective concentration called the minimal inhibitory concentration. This characteristic and the fact that labeled intramammary antibiotic treatments of 1 or 2 days have low cure rates on some chronic subclinical mastitis, have led veterinarians and researchers to apply extended therapy to mastitis treatment.