Blanket Dry Cow Therapy
Blanket Dry Cow Therapy (BDCT) or treating every cow with an intramammary antibiotic at dry off, has served dairy industries in all four corners of the globe well in allowing many herds to hit the mastitis reset button. After all, it was one of the key pillars enshrined in the 5-point mastitis control plan widely employed for the last 60 years. However, its widespread practice comes with significant risk of compromising the effectiveness of critical antibiotics (AB). So much so, that AMR is estimated to contribute to some 10 million deaths by 2050, representing more deaths than cancer.
So, what role can Irish dairy farms play in combating AMR?
Well, when it comes to choosing which cows should or should not receive dry cow antibiotic therapy the decision should be made cow by cow, rather than treating the whole herd automatically.
Scientific consensus and European legislation have aligned to emphasise where Selective Dry Cow Therapy (SDCT) can play its role in slowing AMR. However, this comes with a fundamental change of drying off practices on many Irish dairy farms. This is where we address the aforementioned phrase and use intramammary antibiotics in cows where there is evidence of infection (≥200,000 cells/mL) only (with an internal teat sealant), while only using an internal teat sealant (ITS) to protect the mammary glands of cows with no evidence of previous infection.
Antibiotics treat existing infection, while a teat sealant provides a physical barrier against bacteria entering the udder during the dry period. Research indicates that, when used correctly, teat sealant can be as effective as antibiotics at preventing new infections in cows that are uninfected at drying off. However, excellent hygiene during administration is essential. All teats need to be cleaned, disinfected and sterilised.
Which cows actually need an antibiotic?
Therefore, the key question at drying off is “Which cows actually need an antibiotic?”
Broadly speaking, this decision should be based on individual cow’s SCC trends over the 2026 lactation (and potentially previous lactations also). This information can be reliably obtained through regular milk recording and amalgamating this year’s clinical mastitis history. Both help build a comprehensive picture of your herd. CellCheck recommends carrying out a whole herd milk recording within 30 days of drying off to empower your decision making.
All cows with evidence of infection in the 2026 lactation are eligible for dry cow antibiotic treatment (in combination with ITS). This includes animals with a SCC ≥200,000 cells/mL on milk recording and those which had at least one episode of clinical mastitis in this lactation. In many circumstances, this includes ‘Persistently Infected’, ‘Recently Infected’ and ‘Recently Cured’ animals.
The cohort of the herd which are found on the ‘Healthy’ list are those which are more likely to fall into the eligible category for ITS only – a selective approach. However, as previously mentioned, if any of these animals experienced a case of clinical mastitis in this lactation they should receive dry cow antibiotic therapy. SDCT is therefore about making a risk-based decision for every cow.
However, the appropriate threshold you use can vary according to the infection level within your herd and should be agreed with the prescribing veterinary practitioner.
The ultimate aim is simple: healthy udders, fewer new dry period infections, responsible antibiotic stewardship and cows starting the next lactation in the best possible shape. Good milk recording, accurate mastitis records, effective hygiene and close consultation with your veterinary practitioner are the foundations of a successful dry cow programme which incorporates a selective.
