Recent emphasis on controlling environmental mastitis infection levels may have meant dairy farmers have overlooked the threat posed by contagious mastitis.
Keith Cutler of Endell Vet Group, Salisbury, Wilts, says attention may have slipped from the need to contain levels of contagious infection within herds.
“There has been much publicity about managing environmental mastitis, with such measures as routine dry cow antibiotic treatment and better milking procedures.”
An increase in Streptococcus uberis could also be to blame, he says.
“This may have diverted attention from Staph aureus infections.
Strep uberis is now the most common cause of environmental infection, but Staph aureus can frequently be found in udders of otherwise healthy milkers.
“In our practice, when we begin to investigate mastitis problems, we find that Staph aureus is also often there alongside environmental causes,” says Mr Cutler, who reckons contagious mastitis accounts for about a third of cases he sees.
Post-milking teat dipping, identifying cases early and responding with prompt treatment, culling repeat offenders, 100% dry cow therapy and regular parlour hygiene and testing, and, more recently, cluster dipping between cows, have helped to reduce infections from all sources.
But infection ticking over deep in a cow’s udder can always flare up when circumstances are right.
Prompt antibiotic treatment by farmers, while desirable in principle, can also lead to erroneous assumptions.
“You can’t tell a Staph aureus infection from a Strep uberis infection just by looking at it, even though some people think they can,” he says.
“You have to make assumptions, because you can’t wait 24 hours for tests.
But when you use the wrong antibiotic, Staph aureus buries itself deep in the udder and remains untreated.”
Mr Cutler says more systematic bacteriology, linked to improved dialogue between farmers and their vets can be particularly useful.
Farmers have plenty of useful information at their disposal, he claims.
“Every time they need to treat for mastitis, they should first take a sample from each quarter, label the samples and store them in the freezer.
It takes little space and provides valuable evidence of the initial problem when needed.”