Dry cow therapy practices have grown in popularity in recent decades.
The basic premise – infusing the cow’s teats with antibiotics – was widely adopted in the 1970s and 1980s, and the more recent practice of plugging the teats to block invasive pathogens has caught on in the last 15 to 20 years.
“It made a dramatic impact on the mastitis rates of commercial herds; it can drop the rate of new infection at the dry treating time by 20 percent or more. It’s a really effective way to prevent new infections and eliminate old infections that occurred during that lactation,” Dr. Sarah Place, assistant professor of sustainable beef cattle systems at Oklahoma State University, told Ozarks Farm & Neighbor.
Place said a cow’s mammary glands restructure during the “dry time” and the backup of milk causes the secretory cells to die.
“It takes about 36 hours after the last milking for that process to happen so if you’re going to give that cow treatment, you’re going to infuse antibiotics into the mammary gland at that last milking,” Place said. “It tends to be a two-purpose, broad spectrum antibiotic to try to kill all those pathogens to prevent new infections, because as that milk is building up it can leak out from the teat ends and if the teat ends are open, that can allow pathogens to get in there.”
To prevent that, some producers use teat sealing products that are infused into the teat ends after the antibiotics have been applied. This creates a physical barrier between the teat end and the rest of the mammary gland, and prevents new infections during the dry period.
Reagan Bluel, University of Missouri Extension dairy specialist in Barry County, Mo., said research has sought to find whether producers can move away from the blanket use of broad spectrum antibiotics during the dry period.
“We can look at the level of subclinical mastitis as indicated by somatic cell counts, and determine if we can use a different approach through investigating the different organisms that are in the quarter and treating appropriately,” Bluel told OFN. “But as most studies indicate, if the decision is based exclusively on economics, you have to consider that treating every quarter of every cow would be preferable.”
Another alternative is the use of the teat sealant without applying antibiotics.
“The teat sealant’s goal is to work with or replace the natural keratin plug that is known to block the teat canal, and seal it off during the dry cow period,” Bluel explained. “Different products are in the marketplace; most of them have a paraffin wax as their predominant ingredient, and those internal sealant infusions can be very helpful in cows that are identified as low-risk, or having no infection in the gland, as an effective way to minimize the chance of new intramammary infections from forming.”
Bluel recommended that producers consult with Extension personnel or a veterinarian before moving to selective dry cow therapy.
“If you miss one of the infections in a quarter, the dry cow period or window can be hard for the cattle because the actual, physical act of milking, that forcing mechanism, is very helpful to prevent the intramammary infection from getting worse,” she said. “When we stop milking that cow during the dry cow window, that can increase the prevalence of that pathogen in the mammary gland and can create issues for the subsequent lactation. So you need to make sure, not only through low somatic cell indications but also through considering on-farm monitoring of different organisms, that these cows are truly free of mastitis when they go dry.”
