Picture - Seán Doorley
The incidence of Summer Mastitis tends to vary from year to year with it being a particular problem in many herds this year because of the dry weather.
It mainly occurs in the June to September period affecting dry cows and in-calf heifers when fly numbers are highest. In reality, however it can occur at any time of year.
- Cause -
The primary causal organism is Actinomyces pyogenes in conjunction with other organisms that either enhance its activity or allow infection to develop.
It is a very severe form of mastitis causing udder damage, high temperature and toxaemia. Infected quarters are generally lost and treatment is focused at saving the animal and preventing pregnancy loss.
The infected quarter becomes swollen and hard. When the quarter is drawn the strippings will be foul smelling. The extract may appear clear or with soft to cheesy type curds and as damage progresses there may be traces of blood.
- Prevention -
Where possible prevention is the preferred policy. There are several areas of prevention to consider such as: Fly Control, Grazing Conditions, Teat Damage and the isolation of infected animals.
1) Fly control
A number of pour-on products are available to control flies. They are based on synthetic pyrethroids such as permethrin and deltamethrin. It is recommended to apply these along the back of the animal but is probably no harm to direct some around the udder area as well.
A number of these products will give cover for 4 weeks but in a year when the incidence of Summer mastitis is high, it should be applied every 2 weeks.
Ear tags containing Cypermethrin are also available for fly control. Other farms have been applying Stockholm tar on the udders of susceptible animals. Although it will deter flies it is messy and may need to be applied every 4 - 7 days.
2) Grazing Conditions
Where animals are let graze during the dry period may have a bearing on the level of flies.
It is advisable to avoid fields that are well sheltered with a lot of tree cover. Try and keep the fields topped to reduce tall weeds or old senecent seed heads, which can provide cover for flies or can aid in the spread of infection as animals walk around the area.
3) Teat damage
Animals with any teat soars should be housed.
Soars will only attract flies and increase the likelihood of infection.
4) Isolation of Infected Animals
Animals showing signs of infection should be removed from the group and kept isolated.
If the infected quarter is milked out, he strippings should be carefully discarded because of the risk of spreading infection. In all cases consult your vet for advise on prevention and treatment of summer mastitis in your herd.