Who should consider selective dry cow therapy and why?

Antimicrobial resistance (AMR) is rising and it is not just happening at farm level. AMR is linked to increased antibiotic use in both humans and animals and estimated to cause as many as 25,000 deaths in the EU each year. Consequently, selective dry cow therapy has become a hot topic for discussion, as of late.

Recently, AMR in humans is being linked to antibiotic use in animals; hence, why there is increasing scrutiny of the use of antibiotics in the agricultural sector.

And so, as part of EU regulation governing veterinary medicinal products, an effective blanket ban on antibiotic usage will come into effect from January 28, 2022 – with the aim to reduce antibiotic use in food-producing animals.

After this date there will be strict restrictions on antibiotics and a significant increase in milk recording levels will also be required.

Although, antibiotic dry cow therapy undoubtedly has an important role to play in treating infections that persist at the end of the lactation and in maximising cure rates. According to Animal Health Ireland (AHI), the practice of dry cow therapy is being questioned in many countries – by farmers, consumers and society in general.

So, while it has been traditionally used to prevent new infections occurring over the dry period, this, AHI says, is no longer acceptable.

Quoting recent published analysis, the organisation indicated that sales of dry cow intramammary antibiotics were sufficient to treat 100% of the national milking herd (all quarters of all cows being treated at the end of lactation).

This is what is referred to as ‘blanket dry cow therapy’, which, until recently, was recognised as best practice in mastitis control and has made a very positive contribution to udder health in many countries.

But as AHI says, as it learns more about AMR and what drives it, it needs to review what is considered as best practice – as well as the implications of modifying those traditional recommendations.

Selective dry cow therapy

Selective dry cow therapy (SDCT) has become popular as an alternative to blanket dry cow therapy. This involves giving only teat sealer to a selected proportion of the cows at drying off – with the rest receiving an antibiotic and teat sealer.

AHI did emphasis, however, that while this is reducing antibiotic use, this practice is not without its risks and it is not a case of ‘one size fits all’.

AHI has identified the following risks:
  • Hygiene at drying off – which it says is critical to success;
  • Missing the opportunity to cure quarters that were infected at the point of drying off.

Is SDCT suitable for my herd?

According to AHI, all decisions around dry cow therapy should be made in consultation with a vet who has knowledge of the herd, its history and environment.

There are certain criteria that the herd, and then the cows within that herd, should meet before being considered for SDCT – as it is not a case of ‘one size fits all’.

SDCT may be considered in herds where:
  • There is good evidence of a low prevalence of infection, e.g the bulk somatic cell count (SCC) is consistently below 200,000 cells/ml and a dry period new infection rate of less than 10%;
  • High levels of hygiene can be achieved at drying-off, throughout the dry period and at calving;
  • Regular milk recording is carried out with at least one recording in the last month prior to drying off;
  • The herd keeper is willing to engage with their veterinary practitioner in decision making around their dry cow treatment program.

For herds who are milk recording, at least four milk recordings should have been carried out in the lactation of using SDCT.

Within suitable herds

Within these suitable herds, AHI says, cows with a SCC consistently below 100,000 cells/ml throughout the lactation and with no history of clinical mastitis cases may be considered suitable for teat sealer only at drying off – provided high levels of hygiene can be achieved during administration.