Dr. Michaela Kristula, of the University of Pennsylvania School of Veterinary Medicine, began her presentation on mastitis management by telling dairy farmers that they are the most important factor in controlling mastitis in their dairy herds. High-quality milk is within your reach, she said, if you simply establish a protocol for managing mastitis and make sure it is routinely and consistently followed.
“There are a lot of steps to making quality milk,” Kristula said. “The most important thing to improve milk quality on dairies is that producers implement a mastitis management plan.”
Motivated producers are the main factor in obtaining mastitis management. A motivated producer is one who has a well-thought-out plan in place and who ensures all employees understand the importance of their role in managing this costly disease.
Putting a premium on quality milk – milk that has a somatic cell count of less than 150,000 – and offering workers incentives for keeping the SCC low can go a long way to having a plan in place that works.
Protocols
The key to producing quality milk is having protocols in place to manage mastitis, Kristula said. While the protocols for each dairy may be different, the steps to establishing a protocol are the same. The first step in any protocol is implementing this policy: No milk from infected quarters gets into the bulk tank.
It’s not enough to say that milk from quarters with clinical mastitis doesn’t get into the bulk tank. You have to have a milking procedure in place that ensures workers recognize and isolate cases of clinical mastitis, and that the workers are motivated to follow the established routine.
Every step of your farm’s milking protocol must be performed by every worker on every cow, at every milking, Kristula said. Forestripping is essential and must be included in the milking routine.
The next step, once a milking procedure is established and put into action, is to identify the pathogens already present in the herd. Unless the pathogens are identified, you can’t treat mastitis effectively. Milk from the bulk tank and samples from infected quarters should be cultured routinely to establish the likely pathogens in the herd.
The third step in a mastitis management protocol is to clearly identify the steps a milker must take when a case of mastitis is found. The less complicated, the higher the compliance rate, Kristula said. She recommends segregating cases by severity, with mild cases – severity scores of 1 or 2 (SS1 or SS2) – following an established plan while the plan for cases with a severity score of SS3 are treated more aggressively.
Finally, a farm’s protocol is not complete unless there is a defined endpoint for all scenarios. The best outcome, of course, is a cure, and treatment is no longer needed. But if treatment is not effective, what happens? Having a flowchart which delineates the step-by-step procedures, taking into account all possible outcomes, is the key to making treatment decisions that work.
“These endpoints are challenging to decide upon,” Kristula said.
Identifying pathogens
Once it’s understood that milk from a quarter with clinical mastitis must never reach the bulk tank, and milking procedures have been implemented to make sure it never does, putting a detailed plan in place to treat any mastitis infection found is necessary.
“Once you know what the pathogens are in the herd, then you need to know how to treat those pathogens,” Kristula said.
Treatment and control programs differ depending on the type of mastitis found. If the mastitis is coming from contagious bacteria – Staphylococcus aureus, Mycoplasma bovis or Streptococcus agalactia – it will be spread cow to cow during milking. Post-milking teat dipping, individual towels, wearing gloves and dry cow treatments are needed.
Mycoplasma bovis, seen often in expanding and stressed herds, warrants culling of infected cows, while Streptococcus agalactia is easily treated with antibiotics. Antibiotic treatment in early cases of Staphylococcus aureus, which tends to cause subclinical mastitis, can be effective if cows are identified and segregated.
Once established, however, culling will be necessary. In any case, cows with Staphylococcus aureus should be identified and segregated. There is general agreement that cases of mastitis yielding “no growth” on culture do not require antibiotic treatment.
For environmental mastitis, mild gram negative infections caused by bacteria such as Escherichia coli often self-cure, while those caused by Klebsiella spp. may benefit from antibiotic therapy. The non- agalactia species of Streptococcus require antibiotic treatment.
Coagulase negative Staphylococcus spp. (CNS) tend to respond to short-term antibiotic treatment. There is no effective treatment for mastitis caused by pathogens such as Pseudomonas, Serratia, Trueperella pyogenes or the algae Prototheca. Environmental bacteria tend to cause clinical mastitis, which can sometimes become chronic. Because they grow rapidly in feces, cleanliness is paramount.
With environmental bacteria, “control is focused on the environment and having a clean teat,” Kristula said.
Treatment protocols and resolutions
Deciding when and how to treat the various causes of mastitis may be different on each farm. Some farms may opt for an empiric model, where all cases of mild mastitis are treated based on the farm’s primary pathogens.
Others may prefer the culture-based treatment approach, where every case is cultured. Mild SS1 or SS2 cases would not be treated for 24 hours, until the results of the culture were available. Severity score 3 cases would be treated immediately, based on primary pathogens, but cultured for verification.
An empirical approach, such as using the same antibiotic to treat every case of mastitis Kristula said, is less complex, more readily implemented and has better compliance rates. The withholding of milk from infected cows is simple. However, some cows will be treated needlessly with antibiotics.
In the culture-based approach, the options for treatment are more detailed, based on identifying the infectious agent in each case. Treatment would then be decided based on causative agent. This approach is more complicated, requires time and material for culturing each mastitis case, and requires a dedicated team. It can eliminate unnecessary antibiotic use.
No matter which approach is taken, every farm must continually monitor the results of its treatment protocols. The successful endpoint of any given case can result in a cow cure, where the cow is no longer sick and milk production returns to normal levels, or a quarter cure, where the milk is saleable with a low SCC.
These endpoints should be clearly defined, indicating that treatment can be terminated. If the prescribed treatments are not effective, however, each dairy will have to decide what the next steps are in their mastitis management plan. Some options are to stop milking a quarter or a therapeutic cessation of lactation.
Deciding when to stop – or even not start – the treatment protocol is also a part of the plan. Older cows, for example, have higher rates of recurrence and are less responsive to treatment. Some dairies may opt to cull older cows without treating them.
Protocols serve to ensure that every dairy is producing high-quality milk by taking steps that prevent milk from infected quarters from ever reaching the bulk tank. Having an established milking protocol in place to reduce the likelihood of transmission is essential.
Identifying farm pathogens and taking steps to eliminate their presence is necessary. Treatment flowcharts, designed to consistently treat all instances of mastitis and which are based on clinically-appropriate responses, can be empirical or culture-based. In either case, results are monitored, and an endpoint for every conceivable outcome is defined in advance.
Having a protocol means that there is no “guesswork” involved in mastitis management, Kristula said. This leads to an increase in treatment success. PD
Dr. Michaela Kristula, University of Pennsylvania field service veterinarian, presented this workshop at the Penn State Mastitis and Milk Quality Conference, held March 2014, in Grantville, Pennsylvania.
Tamara Scully, a freelance writer based in northwestern New Jersey, specializes in agricultural and food systems topics.
