The never ending Strep. uberis challenge

What are the consequences of turning cows out with unresolved mastitis problems? When Strep. uberis is involved, they could be huge

Spring is traditionally the chance for staff to look forward to an easier, and more varied, workload. But unfortunately, the winter grind of high cell counts and treating clinical cases of mastitis will continue for some.

That’s because, as the most recent data from Intervet’s Cephaguard® milk testing scheme shows, Strep. uberis continues to be the problem bug on many farms. Between February 2006 and March 2008, Strep. uberis was responsible for causing 18% of high cell counts (SCC) and 23% of clinical cases.  Researchers have now found that there are two strains of Strep. uberis – one that acts as an environmental bacteria (spread in the parlour or on bedding) and one that is contagious (spread cow to cow).  Cows infected with the contagious strain of this bacteria will be taking it out to grass. As a result, milking operators will be faced with a summer of longer milking times, greater stress levels and rising costs – all from detecting and treating mastitis.

The rising trend of Strep. uberis continues to be worrying for vets because this bug causes repeat cases, persistent high SCCs and persistent infections which are often resilient to treatment, says Intervet’s large animal veterinary adviser, Rosemary Booth. “It can also create problems with Bactoscans and behaves in both a contagious and environmental manner. Treatment programmes, therefore need to contain a combination of parlour and housing control measures.

“Turnout tends to herald cleaner times, so you expect to see less environmental contamination at grass. The environmental strain tends to respond well to treatment and a decent dry summer reduces clinical cases. However, the cow-adapted strain of Strep. uberis means that it is spread from cow to cow at milking which becomes a parlour hygiene issue. And it means the risk of a Strep. uberis problem is just as great as when cows are inside. Plus, the cow adapted strain appears tougher and harder to kill.”

This makes bacteriology even more important to find out whether Strep. uberis is present in a herd to successfully tackle a mastitis problem. Miss Booth recommends producers use services such as the Cephaguard diagnostic scheme, carried out by the Vale Veterinary Lab. She explains that this is based on regular sampling and a questionnaire. The lab then produces a report which interprets the results and suggests management techniques to help.

While it can’t pinpoint the exact strain of Strep. uberis, it can indicate whether it is a cow-adapted one using the herd’s mastitis history (such as having to re-treat many cases), regular bacteriology and the presence of other contagious bacteria such as Corynebacterium bovis or Staph. aureus.

The results and the report should then be discussed with your vet. “You need to be as sure as possible when you are treating that you will get a cure. Work with your vet on appropriate treatment protocols: it’s worth, at the start of summer, making sure they are effective as they might need to be more aggressive. Take pre treatment samples for the freezer. If mastitis comes back then get it checked for the bacteria responsible. There isn’t a strict cut-off point, but I would say that if a cow gets mastitis again within four weeks of her last one it may well be a recurrent case and possibly Strep. uberis.”

In addition, vets will recommend a number of parlour routine changes from operators wearing clean disposable gloves to pre-dipping, or cluster disinfection between cows. Another option is treating high SCC cows. This is more cost effective where contagious bacteria are involved because the payback from discarding milk is reducing the risk of spread to the rest of the herd, says Miss Booth. “Treating subclinical Strep. uberis can shorten the duration of infection and reduces that chance of spread,” she adds.

It may sound like a summer of winter work, but without such measures incorporated into the routine, the workload will surely rise in tandem with the level of mastitis.

Strep. uberis in summer

• Causes 23% clinical cases
• Contagious strain harder to kill
• Regular bacteriology