Selective Dry Cow Therapy: Is Your Herd Ready?
What may be less clear is determining whether your farm is a good fit for a selective protocol and how to confidently decide which cows should receive antimicrobial treatment.
It may seem like a game of Russian roulette, but I am here to share that a fortune teller is not needed in order to make good decisions at dry-off. We just need some data and clear, evidence-based benchmarks.
Is Your Herd a Good Fit?
According to Dr. McCubbin and others, two factors to evaluate when determining if your herd is a good fit are bulk milk somatic cell count and incidence of clinical mastitis.
A benchmark for bulk milk SCC that can be used is 250,000 cells/mL. Factors that play a role in determining bulk milk SCC and the incidence of clinical mastitis should also be considered. These include good management at the time of dry-off procedures (cleanliness) and type of mastitis pathogens present. It is also important that there are good records available, as we need to be able to review data on prior history of clinical mastitis and antimicrobial treatments.
Moving From Herd-Level to Cow-Level Decisions
When selecting cows, the goal is to identify cows that are likely already infected and would respond to treatment and cows that have a greater chance of developing an infection during the dry period.
Researchers at the University of Calgary suggest using the following protocol to determine whether a cow should receive only teat sealants at dry-off or whether the cow should be dried off using a combined antimicrobial and teat sealant approach. The information that needs to be available and gathered first is SCC on the last three tests.
If the average SCC of the last three tests is over 200,000 cells/mL, then it is recommended to use both an antimicrobial and a teat sealant. However, if it is under 200,000 cells/mL, we will then confirm SCC at the last test is under 200,000 cells/mL. If that threshold is met, we will want to confirm that there has not been more than one clinical mastitis case during the last lactation. When these three parameters are met, a teat sealant without an antimicrobial can be used at dry-off.
The Role of Teat Sealants
Although teat sealants cannot be used in place of environmental management (good management of dry cow housing is critical), they are helpful in creating a physical barrier between the surrounding environment and the teat canal. Without teat sealants, teats can remain open and susceptible to pathogens in the environment. For cows that are entering the dry period without an existing intramammary infection, use of internal teat sealants has been shown to reduce the likelihood of acquiring a new infection during the dry period.
Why Should You Consider Selective Therapy?
The benefit of this approach is not just the potential cost savings on treatment but also a move toward improved antimicrobial use on dairy farms.
Antimicrobials for the prevention and treatment of mastitis represent close to 65% of antimicrobials used on dairy farms. With the increased emergence of antimicrobial resistance worldwide and increased exposure of livestock farm workers in particular, we all need to be mindful of the role we are playing in antimicrobial resistance.
The take-home message: As my mom and grandma would say, it is good to be selective! However, selective dry cow therapy is not for every farm (in its current state). Taking the time to evaluate herd readiness and apply clear selection criteria at both the herd and cow level is what makes successful implementation possible.
Previously published in "Lancaster Farming" on March 3, 2026.
