Understanding the economic impact of mastitis therapy
the role of duration and drug selection
Mastitis occurs on all dairy farms, and veterinarians can help producers reduce losses and promote more judicious antimicrobial usage. In the US, 7 intramammary (IMM) antibiotics are approved for treatment of mastitis, but no antibiotics are approved for systemic treatment of mastitis. Most cases of clinical mastitis present with mild or moderate clinical signs and there is no evidence that use of systemic antimicrobials is of benefit. Farmers typically underestimate costs associated with treatment of clinical mastitis, and about 75% of costs are associated with milk discard. Selection of drugs and duration of treatment are both areas that can have significant impact on economic losses associated with mastitis therapy. The distribution of etiologies is associated with the value of antimicrobial therapy, and use of intramammary antibiotics should be determined based on knowledge of etiology. Clinical outcomes of most mastitis cases that are culture-negative or caused by E. coli are not improved by use of antimicrobials, and considerable losses can be incurred when longer-duration therapy is used as the standard protocol. When etiology of non-severe clinical mastitis is unknown, use of narrow-spectrum IMM antimicrobials for short duration results in optimal economic outcomes.