Summer mastitis is an acute infection of the non-lactating bovine udder which commonly results in the loss of the affected quarter.
The typical case is presented with a high temperature and a hot, hard and swollen quarter with an engorged teat. This is very painful and the animal is often lame and may have swollen hocks.
When the quarter is stripped, the secretion is thick with clots and has a characteristic smell. These typical signs do not always occur and sometimes all that is found when a cow calves is a `blind' quarter, in these cases the teat feels as if it has a thick core down the centre.
The disease appears in the main to be associated with transmission by the sheep head fly (Hydrotea irritans) which can carry Arcanobacterium (Corynebacterium) pyogenes, the main bacteria involved. These flies are found around bushes and trees and prefer damp ground sheltered from the wind.
They fly out and feed on cattle landing on the legs, belly and udder. The majority of cases occur in the front quarters and this is thought to be because these teats are reached more easily.
The corner stones of prevention are dry cow management and fly control. Choice of pasture for dry cows can reduce the risk by keeping the dry cattle away from fly areas.
Housing dry cows and heifers over the risk period can greatly reduce the risk also.
Fly repellents can be used but their effect may be limited due to their mode of action on the body. Stockholm tar is used successfully by many but the repeat applications required can be problematical. Barrier methods of protection such as tape have been successful but it often needs replacing and recently teat sealants have become available, but these are only really useful for low cell-count cows.
Antibiotic dry cow therapy is also used to help stop this condition and it is sensible to carefully consider the brand of tube that will suit a particular farm and period of risk. It is important to remember that dry cow tubes are for prevention, not for treatment.
The dose of antibiotic is lower than in `milking' cow tubes and in a very slow release formulation. Dry cows with mastitis should receive treatment with `milking' cow tubes and usually injectable antibiotics also.
Aggressive treatment is required to get a reasonable outcome and the sooner in the disease the treatment begins the better! Your vet will be able to advise you on suitable treatment protocols based on their knowledge of your farm. A problem I come across a lot is the reluctance to strip out the udder after putting in tubes. The perception seems to be that having just put expensive drugs into the quarter you don't want to remove them.
This in part is true. But very quickly after the infusion, the drug has diffused into the tissue and striping the quarter can begin again.
Any toxins released into the udder by the disease are better on the floor than in the blood stream!
Now is the time to get prepared and consider your preventive measures.