“We've come a long way in the past 50 years,” said Linda Tikofsky, DVM, senior associate director of dairy professional veterinary services, Boehringer Ingelheim. “The dairy industry has made significant improvements to cow comfort and nutrition, as well as mastitis treatment and detection. As a result, contagious mastitis is no longer the main issue. Now, producers face environmental mastitis, which causes clinical cases and is easy to detect during lactation.”

 

With this shift in mastitis cases and advanced management, it may not make sense for all producers to continue using blanket dry cow therapy. Selective dry cow therapy (SDCT) — where antibiotics are only used to treat cows with likely intramammary infections — is an opportunity for producers to cut down on antibiotic use. In fact, research has shown that SDCT can reduce antibiotic treatment by two-thirds.¹

 

SDCT is worth consideration, but it isn’t for everyone. Take the quiz below to see if it’s a viable option for your dairy:

1. Is your herd somatic cell count consistently less than 200,000?

If your dairy frequently bumps up over 200,000, or even 150,000, then SDCT isn’t the right fit for you. 

2. Is your herd free of contagious mastitis?

For herds that struggle with contagious mastitis, most commonly caused by Staphylococcus aureus, SDCT is not a viable option. Dry cow therapy is one of the most effective tools against contagious mastitis because it will tackle subclinical infections at dry off.

3. Do you participate in a milk testing program?

Collecting milk samples for somatic cell testing through the National Dairy Herd Improvement Association on a monthly basis is an excellent way to track the proportion of cows that struggle with mastitis or have consistently high somatic cell counts (SCC). The data can help producers choose the cows that need treatment at dry off versus the ones that don’t.

4. Are you keeping thorough records?

SDCT requires outstanding data analysis and record keeping. Dairy employees should be meticulous when collecting, organizing and handling data, so the right cows are treated at dry off.

5. Are you using a teat sealant?

“We’ve learned that more than 25% of cows don’t form a keratin plug at dry off,” said Dr. Tikofsky.² “So, if we’re not using an antibiotic in those quarters, we need to make sure we’re giving cows physical protection with a teat sealant.”

6. Is your staff well trained?

A SDCT program is most successful when staff are well trained and have a comprehensive understanding of dry cow procedures.

7. Are you using a coliform mastitis vaccine?

Coliform mastitis was the source of 50% of mastitis infections in U.S. dairy herds.³ “We want to make sure we’re protecting cows with vaccination,” advised Dr. Tikofsky. “An effective mastitis vaccine should have a short meat withdrawal and provide coverage against Escherichia coli and endotoxemia caused by E. coli and Salmonella Typhimurium.”

 

If you answered “yes” to all of the questions above and feel confident in your mastitis management practices, it’s time to bring your veterinarian and employees together to discuss SDCT implementation options. There’s less forgiveness in SDCT — it requires a team approach.  

 

There are two schools of thought on how to implement SDCT:

• Culture-based SDCT collects and cultures milk samples two days before dry off. Cows that have one or more quarters test positive for mastitis are given antibiotics.
• Algorithm-based SDCT uses records from farm management software. Cows who meet any of the following criteria are treated:
  • SCC averaging 200,000 or greater on the last three tests and the last test before dry off
    • Any clinical mastitis cases in the last 14 days before dry off
    • Two or more clinical mastitis cases during the current lactation

 

A study compared culture-based versus algorithm-based SDCT and found no difference in efficacy. All of the study herds were able to reduce antibiotic use by about 60% without negatively affecting cow health or milk production.^4,5

 

“A lot has changed in the last 50 years, but producers have remained committed to animal stewardship,” said Dr. Tikofsky. “Moving forward, I think we'll see more of a switch to selective therapy. It’s a way to be extraordinarily proactive and can have a lasting impact on animal health, food safety and consumer confidence in dairy products.”

 

References:

¹ Vasquez AK, Nydam DV, Foditsch C, et al. Use of a culture-independent on-farm algorithm to guide the use of selective dry cow antibiotic therapy. J Dairy Sci 2018;101(6):5345–5361.

² Ruegg P. Managing the dry period for quality. University of Wisconsin. 2011.

³ Continuing market study. Research Department, Hoard’s Dairyman. 2018.

⁴ Rowe SM, et al. Randomized controlled non-inferiority trial investigating the effect of 2 selective dry-cow therapy protocols on antibiotic use at dry-off and dry period intramammary infection dynamics. J Dairy Sci. 2020.

⁵ Rowe SM, et al. Randomized controlled trial investigating the effect of 2 selective dry-cow therapy protocols on udder health and performance in the subsequent lactation. J Dairy Sci. 2020.

 

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