Now is the time to be keeping an eye out for summer mastitis, as Aly Balsom found out when she spoke to Dorset vet Lucy Gill.
Being vigilant and putting steps in place to prevent summer mastitis is a must at this time of year, especially considering the low chance infected quarters have of recovery, says Lucy Gill, of Friars Moor Veterinary Clinic.
The fact the disease effects the non-lactating mammary gland means careful observation of dry cows and heifers is particularly important, especially during the high risk period of July to September.
Attention should also be paid to steers and calves which can develop the disease, although less commonly. Beef farmers should remain vigilant too as autumn calvers in particular could also be at risk. Failure to pick up on issues could lead to animals calving in with blind quarters or even udder ‘blow outs’.
Miss Gill says the disease is commonly seen on specific farms and specific fields, with the high risk period coinciding with when fly populations are at their height.
“The bacteria, trueperella pyogenes is the main cause of summer mastitis and this is spread by the sheep head fly. However, it is thought it is not just the fly and there is probably some other predisposing reason on the teats, such as teat damage.”
Any teat damage from thistles or thorns, biting flies or common warts seen on youngstock can potentially attract the sheep head flies. There is then the risk the bacteria will enter the teat and spread up into the mammary gland.
The pus characteristics of the causal bacteria means infection is difficult to treat, with the chance of recovery ’fairly hopeless’ and the animal typically losing the affected quarter.
“It is important to be vigilant. Infected animals will generally appear sick, be away from the group and walk a bit stiffly. When you look at dry cows and heifers, look at udders and look for any uneven swelling,” says Miss Gill.
Although it is unlikely an infected quarter will be saved, Miss Gill emphasises speed of treatment is crucial in preventing the quarter from bursting and infecting other quarters.
As infection causes an abscess in the udder, the first thing to do is to thoroughly strip the infected quarter.
“Drainage is essential to get the pus out. The milk which comes out will be a yellow custard and foul smelling. You need to strip the udder several times a day for the first few days and get rid of the strip material safely,” she says. “It is also important to isolate the animal, as if you leave it with others, there is the potential for flies to spread the infection.”
Treating with an injectable penicillin antibiotic will help tackle the infection, while using an anti-inflammatory injection will help bring any temperature down to reduce abortion risk and any swelling.
Due to the fact treatment is largely a salvage operation, prevention should be the aim (see below).
Summer mastitis prevention should be focused around reducing the risk of fly transmission and predisposing factors on the udder:
Dry, cracked teats or cut skin will be more at risk of infection, so maintaining good teat condition through good milking and grazing management is an important part of prevention.
Over milking leading to hyperkeritosis is a big risk factor. Make sure cows are not over milked, cows are dried off with good teat condition and include an emollient in your post-dip.
Treating warts and thinking about grazing location are key considerations for youngstock. Ideally areas with high thistle populations or long grass should be avoided on farms where summer mastitis is a risk.
Fly control is a vital component in preventing summer mastitis as the sheep head fly transmits the bacteria and biting flies damage the teats, predisposing them to infection.
Good fly control is really important – either use repeated pour-on or fly tags if handling is not easy. “The challenge is they are not great at control on the udder skin, so it makes sense to put a half dose of pour-on rubbed into the udder if a farmer knows there is a risk there [of summer mastitis],” says Miss Gill.
Ideally fly control should start early in the season to prevent fly populations from building up. Miss Gill suggest using a standard pyrethroid-based fly control product and reapplying regularly in-line with product guidelines.
As flies favour wooded and wet areas, these grazing locations should also be avoided when summer mastitis is a risk.
Dry cow therapy and teat sealants also play an important role in prevention. Sealants in particular help stop the infection entering the teat end.
“If a farm has issues with summer mastitis in dry cows, use dry cow therapy with an antibiotic that persists for longer.
There are also some external teat sealants which can be applied like a post-milking teat disinfectant, but these are generally not used as they are not very practical.