Most Likely To Need Treatment


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For years, dairy producers have routinely treated every cow with antibiotics at dry off. The risk of contracting mastitis, an economically important disease, at this stage made blanket dry cow therapy (BDCT) commonplace.

Blanket treatment at dry-off has been an industry standard since the 1960s. Its adoption is credited with improving milk quality, notes Mauricio Rosales, dairy educator, PennState Extension.

“It helped the industry move forward to be better producers,” Rosales says. “Unfortunately, right now, we’re experiencing antimicrobial resistance in humans and animals. The industry is looking at different alternatives to decrease utilization of antimicrobials.”

One strategy is selective dry cow therapy (SDCT), where only cows diagnosed with mastitis receive treatment. SDCT was developed in the 1990s. Adoption has been limited in the United States but is more widespread in Europe where blanket treatment has been banned in some countries, Rosales explains.

SDCT offers producers a way to address consumer concerns, but it can add additional time and recordkeeping, explains Curt Vlietstra, DVM, professional services veterinarian, Boehringer Ingelheim.

“With blanket therapy, every cow and every quarter gets treated with antibiotics at dry off,” Vlietstra says. “The advantages to that are, from a management standpoint, there is no additional labor and no additional recordkeeping. You know when a cow gets dried off, it’s treated in all four quarters to clear up any low-grade infections, or existing infections, and provide a little protection into the first week of the dry cow period.”

On the other hand, selective therapy requires producers to choose specific cows to receive antibiotic treatment. In return, producers use – and purchase – less antibiotics, but additional recordkeeping is required to identify those cows and track treatments.

Currently, producers and industry experts are debating the best criteria to use for selecting those at-risk cows, Vlietstra notes.
Selecting cows
The gold standard for definitive identification of disease infection is culturing cows. The drawbacks to this method include both the length of time a culture may take and the associated costs and recordkeeping, Vlietstra says.

In practice, producers may consider the cow’s health history and somatic cell count (SCC) scores from the monthly Dairy Herd Improvement Association (DHIA) report.

“If the cow really has no history of mastitis, has not been treated and did not have a high SCC, that’s a cow that may not get treated at dry off,” he says. “The culture is one more step that can take 24 to 48 hours before producers will have the information to decide to treat or not. It simply takes time for the bacteria to grow in a culture, and it’s difficult for large dairies to do this for every cow.”

When using history of treatment as the main criteria, the timespan can vary from herd to herd. On some farms, a single treatment early in the lactation may not indicate treatment at dry off is needed.

“If she had a case when she was fresh, dry off may be seven months later,” Vlietstra says. “As scientists, we want everything to be repeatable and standardized, but no two farms are the same. No two cows are the same. Each farm’s management is different, and their goals are different.”

There is an opportunity for improved testing for mastitis. Ideally, producers need a test combining the accuracy of a culture with quicker availability of results.

Rosales says larger farms could purchase polymerase chain reaction (PCR) testing equipment to identify the specific organisms affecting their cows. Then, an antibiotic targeting those organisms can be selected.

“The technology is relatively expensive at the moment,” he says. “It could be an option if farms are having constant problems or under certain conditions.”

Antibiotic reduction
Vlietstra estimates a dairy operation could reduce its antibiotic usage at dry-off by 60 percent.  The cost savings is enticing to producers looking to reduce expenses. Yet, increased time and labor must be calculated too.

“Good producers are very aware of the consumer perceptions and concerns about antibiotics,” Vlietstra says. “Ultimately, what’s going to drive adoption of selective therapy is benefits to both sides. Increased management isn’t free, but consumer concerns are definitely on the list of decision-making factors.”

Consumer concerns must be taken seriously or risk turning into regulations, Rosales notes.

“Look at the situation today. We’ve had BST taken away, we have regulations requiring vets have to sign off on some feed additives. Little by little, regulations are increasing,” he says. “We need to make sure we are ready for this. If we have a conversation with producers and explain that selective therapy is not difficult – and perhaps it’s going to have an impact on the bottom line of the farm – we can stimulate producers to adopt it.”
Slow adoption
SDCT is not common on U.S. dairy farms. Most are comfortable with blanket treatment and view selective therapy as increasing their risk for disease. There also has been no documented link between dry cow therapy and increased antimicrobial resistance.

“As a matter of fact, I haven’t met a producer trying to do selective therapy on their farm,” Rosales says. “Blanket treatment is fast and easy. We need to think about this more seriously as an industry and provide education to producers. Regulations are constantly changing. We don’t want to get to a point where this is a law that everyone has to follow.”

Adoption can be successful and beneficial. In some countries in Europe, adoption of SDCT has been successful, and producers have seen positive results, Rosales adds.

Some farms Vlietstra has worked with have tried SDCT and reverted to blanket treatment.

“The industry is not ready to adopt this across the board,” Vlietstra says. “There are farms with other management challenges. In five to 10 years, we’ll learn more about the best way to adopt selective dry cow therapy – and the average farm continues to get better and better at the same time.”

Avoid disease
Reducing incidence of mastitis overall can help improve adoption of SDCT. Producers have already improved vaccination, animal husbandry, nutrition and stall maintenance, Vlietstra says.

“We’ve reduced environmental exposure to disease, improved immune function of the cows through better nutrition and lowered animal stress,” Vlietstra says. “Those types of things are going to continue to be of paramount importance as we aim to address consumer concerns.”

Improved vaccines and more widespread use of teat sealants have improved industry-wide rates of mastitis, Vlietstra notes.

Applying teat sealants to every quarter is already a standard practice and have helped reduce disease incidence. Producers who experimented with SDCT prior to using teat sealants should try again using both tactics, Rosales advises.

“I was talking with a producer who tried selective therapy but didn’t use teat sealant,” he says. “The teat sealant was a game changer for this operation, and I think he will have better success with selective therapy now that he’s using a sealant.”
Industry incentives
Reducing antibiotic use is a necessary industry-wide goal. Vlietstra encourages DSRs to look through their whole portfolio of products to enhance immune function and reduce disease rates.

“It’s not about how much we can sell this farm this year,” Vlietstra says. “This is more about long-term sustainability of the customer – how many years can we keep this farm as a customer – and long-term viability of the industry.”

1 Rosales M. Selective Dry Cow Therapy, An Option to Consider. PennState Extension.

Read more about mastitis treatments in Vet-Advantage’s “Checking for Udder Health” article:https://blog.vet-advantage.com/livestock/checking-on-udder-health

Key Points:1

  • Most dairy farms in the U.S. utilize blanket dry cow therapy (BDCT) to dry off cows.
  • BDCT helps decrease mammary infections during the dry period and to prevent new infections in the upcoming lactation.
  • Selective dry cow therapy (SDCT) is an option to decrease the use of antibiotics in food animals.
  • SDCT is an approach that determines the utilization of antibiotics based on the infection status of each quarter and somatic cell count (SCC) records.
  • Studies have found that SDCT is as successful as BDCT in the prevention and treatment of intramammary infections during the dry period and can reduce the use of antimicrobials by 21 percent.

4 Questions for Selective Dry Cow Therapy

Selective dry cow therapy (SDCT) isn’t right for every herd. It requires a high level of management, says Curt Vlietstra, DVM, professional services veterinarian, Boehringer Ingelheim. It’s important to look at several key factors to determine if it’s an option for your clients’ herd:

  1. Is the herd doing a good job of controlling subclinical mastitis?
  2. What’s the herd somatic cell count (SCC)?
  3. Does the herd have individual SCC records for each cow by month?
  4. Does the dry-off crew have excellent hygienic administration standards for internal teat sealants?
  5. Vlietstra encourages operations who are in line with the above to work with their veterinarian to develop and implement an SDCT program.