20 May 2022

Longford Leader Farming: Keeping summer mastitis at bay


The months of August and September are notorious for summer mastitis infections. 

The months of August and September are notorious for summer mastitis infections. 

It affects dry cows and heifers in both dairy and beef herds.

It is caused by a bacteria and is spread by flies.

Cows can appear dull and have discomfort in their udder when infected. The infected quarter will be swollen, hard and surrounded by flies. The infection normally results in the loss of the quarter. Treatment requires veterinary attention. A course of antibiotics along with either draining the infected quarter for several days by milking it out or the vet cutting the teat to allow draining.


1. The use of pour-ons on cows will help deter flys. The solution is applied on the back of the animal, but it is no harm to apply some of the pour on closer to the udder region. Pour ons will give cover for flys for 4 weeks, but in hot humid weather and fly numbers are high, they should be applied every 2 weeks.

2. Stockham tar is another affective way of prevention. It should be applied by hand on the 4 teats and surrounding quarters of the dry cow using a glove. Spray versions are also available but less affective. The tar will need to be re-applied every 4-7 days.

3. Ear tags containing cypermethrin (an insecticide) can be applied to cows, which will again help deter flys. Putting garlic licks with cows will also deter flys and works quite effectively. A combination of all these preventatives is probably the most effective control of summer mastitis.

Other practical ways that farmers can reduce the level of possible infection are:

1. Avoid letting dry cows or recently weaned cows graze in fields with a good deal of shelter, as there will be a greater number of flies in these areas.

2. Topping fields in order to not let tall grass or weeds build up as these provide shelter for flies, keeping them closer to cattle.

3. Keep a close eye on cows with sore or cracked teats and if weaned, a fly repellant is vital.

4. Animals that become infected should be isolated and the strippings from the infected quarter should be disposed of immediately to reduce the risk of spreading infection to other cows.
When herding dry heifers of any age, dry cows or even sucklers cows always be vigilant of summer mastitis and contact your vet if you suspect you have a case.

Teagasc provides a Local Advisory and Education service to farmers. They have offices based in Longford Town (Tel: 043 3341021), Roscommon Town (Tel: 090 6626166) and Castlerea (Tel: 094 9620160). You can find us on Facebook @Teagasc roscommonlongford and twitter @teagascRNLD.

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