Choose the right tube for the job

Treating a case of Strep. uberis mastitis needs to be aggressive if it’s to succeed and prevent relapses occurring throughout lactation. There is one particular phase in the lactation cycle offering long-term contact with antibiotics that results in an excellent cure and quarters free of Strep. uberis: the dry period.

Recent trial data from Intervet show that its cefquinome dry cow tube (Cephaguard DC®) not only achieved this, but cows were also half as likely to develop clinical mastitis in the first 100 days after calving, compared with those treated using 600mg cloxacillin tubes (see table 1). This is good news for farmers, because figures gathered by Intervet, through its Cephaguard bacteriology scheme, show that Strep. uberis continues to be the problem bug on many dairy farms.

Between February 2006 and March 2008, it was responsible for causing 18% of high cell counts cases and 23% of clinical cases. This bug is resilient; it causes persistent infections and high cell counts, and behaves in both a contagious and environmental manner. Furthermore, the cow-adapted strain of Strep. uberis (spread from cow to cow at milking) is tougher and harder to kill than the environmental strain. Because it lives quite happily in the udder, several weeks of not being milked provide a unique opportunity to kill it with the long-acting antibiotics found in dry cow tubes. “The dry period is a fantastic time to try and treat chronic problems such as Strep. uberis,” confirms Intervet’s large animal veterinary adviser Rosemary Booth.

“From a mastitis management point of view, the aim of the dry period is to try to cure any subclinical infection in the cow as well as prevent any new infection.”

Sometimes, she explains, there is a good case for drying off individual cows early. Those with a chronic infection for example, one that has had several treatments and repeat cases, or cows with persistently high cell counts. If a cow’s contribution to the bulk tank is low and she isn’t helping the bulk cell count, it is may be more cost-effective to dry her off, says Miss Booth.

One of the benefits of the antibiotic cefquinome is that it is very good at invading the Strep. uberis cell walls and killing the bacteria quickly. It is a small molecule which quickly diffuses throughout the whole udder, killing most bacteria shortly after drying off. Yet it is the length of time it is present in the udder, over the dry period, which makes it even more successful. “The bacteria come into contact with so much antibiotic they simply can’t survive – even those lurking deep within the udder.  And any new bacteria entering the udder whilst the antibiotic is present will be rapidly killed, thus reducing the chance of the cow calving down with mastitis.”

Miss Booth recommends that farmers work closely with their vet to be sure that their treatment protocols and dry cow antibiotic are effective against Strep. uberis. One helpful tool is bacteriology. “It’s worth reviewing your choice of dry cow tube to see if it is effective against Strep. uberis if that is found to be present in your herd. You need to be sure when you are treating mastitis, that you are doing everything possible to get a cure.”

TABLE 1

DRY PERIOD CURE RATES (%) OF KEY MASTITIS PATHOGENS