A study published in October 2026 in the Journal of Dairy Science (Volume 109, Issue 10) tests a simple question with real barn-level consequences: does infusing an internal teat sealant a second time, four weeks after drying off, reduce intramammary infection risk across a long dry period?

Authors R.R. Munn, R. Castle and S. McDougall report the work. Their target is the dry period, the stretch when the keratin plug that normally seals the teat canal may form slowly or incompletely — a known window for new intramammary infections in dairy cows.

What problem does a second infusion address?

Internal teat sealants are inert bismuth-based pastes that physically block the teat canal. Producers infuse them at drying off, and the seal sits in place as a mechanical barrier until calving. The logic is straightforward.

The barrier can fail. Long dry periods — often 60 days or more — extend the time the sealant must stay in place, and cows dried off early, or carried longer gestations, face gaps in protection. A second infusion, timed at roughly the four-week mark, would renew the physical plug during the period when the original seal may have degraded or been lost.

The study's design, cow numbers and infection outcomes appear in the full paper in Volume 109, Issue 10, and clinicians should read the results section before changing protocols. The journal has not made the outcome figures available in the citation record reviewed here.

What could change at the herd level?

If the trial shows fewer new intramammary infections in the second-infusion group, the practical impact lands in dry-cow management. Drying off decisions — particularly with selective dry-cow therapy, where antibiotics are withheld and sealant alone carries the protective load — would gain an option for extending coverage.

That matters for two groups of cows in particular:

• Cows with extended dry periods beyond the typical 60 days
• Herds practicing selective dry-cow therapy under antibiotic stewardship programs

A second infusion adds labor and product cost. Producers would need the trial's infection-reduction figures to weigh that cost against treatment savings and milk-quality gains, and those numbers sit in the full paper.

Why the timing matters

The four-week interval is not arbitrary. Research on dry-period dynamics shows the greatest susceptibility to new infection occurs in the days immediately after drying off and again in the pre-calving period, when the natural keratin plug and any artificial seal must hold. Timing a repeat infusion at four weeks positions a fresh barrier ahead of that second risk window.

Teat sealants themselves carry no milk withholding because they contain no antimicrobial, which keeps a repeat application logistically simpler than a repeat antibiotic treatment would be.

Reading the evidence responsibly

The Journal of Dairy Science published the study in its October 2026 issue, and the peer-review standard of the journal gives the findings weight. Still, the citation reviewed here provides the protocol — a second internal teat sealant infusion four weeks after drying off — without the outcome data. Veterinarians advising client herds should pull Volume 109, Issue 10 directly before deciding whether the intervention earns a place in their dry-cow protocols.

Whether the approach becomes a standard recommendation will depend on the magnitude of the infection reduction the authors report, and on follow-up work testing the protocol across herd sizes and management systems.