Factors to Consider When Developing a Selective Dry Cow Therapy Program

Boehringer Ingelheim

On the surface, there’s a lot to like about the concept of selective dry cow therapy (SDCT). Limiting the use of intramammary antibiotics at dry off to cows with previous or current infections could benefit dairy producers on a number of fronts.

SDCT can reduce a dairy operation’s antibiotic use by two-thirds,1 which, in turn, helps decrease medication and labor costs. With the judicious use of antibiotics, producers can also minimize the risk of milk residues, satisfy consumer pressure to reduce antibiotic use, and address antibiotic resistance.

So why has the adoption rate been relatively slow? “There simply isn’t a one-size-fits-all approach to selective dry cow therapy,” explained Curt Vlietstra, DVM, Boehringer Ingelheim, “because the management personnel, bacteria and infection risks aren’t the same on any two farms.”

Avoid potential pitfalls

Critical to the success of any SDCT program is the ability to accurately identify animals that need antibiotic therapy, including those with subclinical infections.

“Although many producers find it difficult to implement on-farm culturing due to the time required,” said Dr. Vlietstra, “most experts agree that a bacterial culture is the gold standard to confirm an infection and the pathogens involved.”



Without a culturing program in place, there’s the potential for infected cows to slip through the cracks, creating increased somatic cell counts and clinical mastitis cases during the dry period. “Dry cows typically aren’t observed as frequently as their lactating counterparts, so cows can become quite sick before they’re identified,” Dr. Vlietstra warned.

Untreated infections during the dry period can lead to trouble after calving. “Clinical mastitis in fresh cows can have a significant negative impact on total milk production for the entire lactation, as well as on survivability,” he cautioned.

The importance of good herd data

“If you can establish an on-farm culturing program, that’s ideal,” stressed Dr. Vlietstra. “But if that’s not feasible, it may still be possible to incorporate SDCT if you have solid herd data.”

In a recent Cornell University field trial using only computer-based records, without milk cultures, researchers developed a computerized algorithm to identify low-risk cows that were less likely to benefit from dry cow antibiotics, as well as high-risk cows for which treatment was advised.1

In the end, the algorithm reduced dry cow antibiotic use by 60%, without negatively impacting production or cow health.1 Of course, most dairy producers don’t have the advantage of a team of experts to develop an algorithm tailored to their operations. That’s why Dr. Vlietstra underscored the importance of having solid herd data and the advice of a trusted veterinarian.

“Together with their veterinarians, producers can review data to decide if SDCT is right for their farms,” Dr. Vlietstra recommended. For those who decide to move forward, “the veterinarian can help determine which data to monitor to make sure a farm isn’t missing warning signs that SDCT may not be working.”


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