Many of my clients are looking for advice on selective dry cow therapy at the moment. Using antibiotics in cows that don’t have an infection could increase the amount of resistant bacteria. Also, less dry cow tubes means less cost and less worry about residue problems in fresh calvers.

However, if infected cows are given only sealer, this will have the opposite effect. There will be more mastitis, leading to more antibiotic usage and much greater costs.

When we dry off a cow with sealer alone, we need to be very confident that she is not infected. We can only be confident that she did not quietly pick up an infection if we are sure that there is very little infection in the herd to spread.

To have confidence in our infection levels, we need to comply with a few simple but strict rules.

Firstly, we need a bulk milk somatic cell count consistently below 200,000 for the whole lactation. Records show that this is now true for over 60% of Irish herds.

We also need to do at least four milk recordings in the lactation and these need to show that there is a new infection rate of less than 5%. Only about 35% of Irish herds currently use milk recording; this is a missed opportunity.

We need to know that we have less than 2% clinical case rate in the last three months of lactation.

That means that for each of the last three months, there were less than two cows with a visible change in milk or udder per 100 cows.

Unfortunately, most of us are not good at detecting clinical mastitis and only a small minority make a note of a clinical case. Without those records, we cannot have the confidence we need. If your herd meets the above criteria, you should begin to use selective dry cow therapy. If not, then I recommend making the changes needed to get to this point before beginning to use selective dry cow therapy. For more advice, please consult your own vet.

Kevin Meaney works with Southview Veterinary Hospital, Clonmel, part of XLVets, a group of progressive practices working together to achieve a better future for agriculture and veterinary in Ireland. See www.xlvets.ie.