Clinical mastitis cure versus bacteriological cure … is there a difference between the two? Does it really matter? In a word, yes. In a few more words, it matters because the difference between achieving one and not both can be the two things that make or break a dairy’s bottom line: lost productivity and increased costs.

Bruno daniela
Dairy Adviser / University of California Cooperative Extension
Senior Veterinarian / Zoetis

A bacteriological cure offers the potential for more milk in the tank

It’s imperative for producers to remember that the key to successful mastitis treatment is ensuring both a clinical and bacteriological cure. Producers should approach mastitis treatment by first understanding what’s possible when achieving a bacteriological cure rather than merely a clinical cure.

A clinical cure means that the physical mastitis symptoms have cleared up, but bacteria may remain in the udder. Too often, mastitis treatments end before the infection is completely cured, meaning pathogenic bacteria may remain in the udder. An incomplete mastitis cure can lead to chronically infected cows, the potential spread of mastitis-causing pathogens and expensive retreatments.

A bacteriological mastitis cure, on the other hand, means not only have mastitis symptoms cleared, but the bacterial load has also been significantly reduced. According to a Cornell University study, cows that achieved a bacteriological cure gave 8.8 pounds more milk than cows that didn’t. Achieving both can mean improved productivity and decreasing the likelihood of relapse and added costs associated with retreatments.

Pay close attention to gram-negative mastitis

A great example of not overlooking the importance of a bacteriological cure is with mastitis caused by gram-negative bacteria. Gram-negative bacteria, such as Escherichia coli, Klebsiella spp. and Enterobacter spp., comes from the environment, including bacteria in the bedding and on surfaces in the barn and parlor, and accounts for up to 35% of all intramammary infections on dairies. It’s common industry practice to let these specific mastitis cases resolve on their own, but a study showed that of 66% of cultured samples that initially tested negative for a gram-negative pathogen, 34% actually were positive for a gram-negative pathogen. The silver lining is that recent research conducted by the University of California – Davis and published in the Journal of Dairy Science demonstrated how it can be better to treat mastitis cases caused by gram-negative bacteria than to leave bacteriological cure to chance.

The study featured three large dairy herds in California and 415 non-severe clinical mastitis (mild and moderate) cases caused by gram-negative bacteria to determine if treatment of these cases improved treatment outcomes. The study showed treatment of non-severe (mild and moderate) cases of clinical mastitis caused by gram-negative bacteria withceftiofur hydrochloride(Spectramast LC) was effective in improving bacteriological and clinical cures, lowering mastitis recurrence, reducing use of supplemental therapy and minimizing mastitis-related culls and deaths. Results showed the effectiveness of two-day treatments was better than not treating at all.

Specific findings from the research included the following:

  • 24.7% increase in bacteriological cures in treated groups at Day 14 compared to untreated groups
  • 46.8% reduction in mastitis-related cull and death rates in treated groups compared with untreated groups
  • $204-per-head reduction of mastitis-related losses in groups treated for two days compared with untreated groups

With this data supporting the case for the treatment of mastitis caused by gram-negative bacteria, dairy producers and veterinarians can be confident in their treatment decisions and protocols to help improve cow wellness outcomes and mastitis treatment-related costs.

Steps to mastitis treatment success

It’s important to note that not all mastitis treatment plans will look alike, and a tailored approach can help ensure success. Here are factors to consider when making a mastitis treatment plan and working toward improved outcomes:

  • Know her health history: Not all cows are good candidates for intramammary therapy. Make decisions based on cows' history and length of infection by culturing milk samples. This is key to judicious antibiotic use principles.
  • Culture mastitis cases: If you culture every case, routine culturing of mastitis cases will allow you to keep a profile of the pathogens affecting your farm over time. Assuming a cow is a qualified candidate for mastitis treatment (based on knowing her health history) while producers are waiting for those results, they can treat with a mastitis treatment that covers a broad range of pathogens and also has a flexible treatment label.
  • Monitor treatment success: Good records and monitoring are the only way to know whether a treatment plan is working. Monitoring treatments helps make sure you're achieving high bacteriological cure rates, lower relapse rates and lower bulk tank somatic cell count (SCC) scores. 
  • Consider a flexible label treatment: A mastitis treatment that covers a broad range of pathogens can sometimes be necessary to achieve a bacteriological cure and help reduce the chance of relapse.

References omitted but are available upon request by sending an email to the editor.