The goals set by milk processors, the ACVM (the group overseeing antibiotic use) and Vet Council are to ensure dry cow therapy (DCT) is used only when there is evidence of quarter infection.
Using DCT only in quarter(s) that are infected should be the gold standard, meaning reduced use of antibiotics and a reduced risk of antibiotic resistance developing. This is positive for both animal and human medicine.
Using information such as individual somatic cell count from herd tests (done within 80 days of dry off), or Rapid Paddle Mastitis Test at time of dry-off as well as mastitis records for the season, allows the determination of which cows and heifers have infected quarters and therefore should have DCT administered. As a guide (SAMM plan recommendations), cows and heifers with somatic cell counts under 150k and 125k respectively are not infected and do not benefit from antibiotic use in the form of DCT; but can benefit from a teat sealant. Therefore, using blanket therapy in this group is an ill-advised use of resources and is an unsustainable programme of treatment.
Another more recent tool is the use of whole herd individual milk cultures in the lead up to drying off to determine which bugs, if any, are prevalent and therefore best treatment option to use on an individual cow and pathogen basis.
Understanding the milk quality aspects of your farm is the key to deciding on DCT and the use of teat sealant. If Blanket DCT is being considered, veterinarians will need to work with you to decide on the need. To guide that decision, the five criteria below have been set for us as veterinarians and need to be considered within our prescribing requirements:
| Measure of infection | Criteria indicative of herds with a high risk of mastitis |
| Bulk milk SCC | Seasonal average is equal to or above 250,000 cells/mL |
| Clinical mastitis in dry period | 2 or more cases/100 cows over the dry period |
| Clinical mastitis in early lactation | 10 or more cases per 100 cows in the first month of lactation |
| Individual cow SCC in early lactation | More than 25% of herd with cow SCC over 150,000 cells/mL at herd tests in first six months of lactation |
| Dry period new infection rate | 15% or more of cows have an increase in SCC from below 150,000 cells/mL, to above 150,000 cells/mL, over dry period |
Veterinarians need to document the decision well. Blanket therapy can only be a temporary measure and farmer and veterinarian must ensure steps are taken on farm (milk cultures, milking time visits) to work out what mastitis risk factors are on farm, address them and return to selective DCT.
The use of whole-herd teat sealant (in combination with selective DCT) provides protection until calving, (up to 120 days protection afforded when used correctly) helping to achieve low mastitis incidence and reduction in season’s bulk milk somatic cell count. We can help train your staff so they can administer Teat seal correctly and minimise potential infections that could be introduced during teat sealing.
Help us to help you ensure that dry cow continues to be effective and available into the future.
