21 June 2002

Strep uberis a threat inside and out

SUMMER dry cow paddocks pose as much of a Strep uberis mastitis infection threat as winter straw yards, warns Institute of Animal Health researcher Elizabeth Berry.

"S uberis infection is now the most common disease pathogen implicated in dry cow mastitis. As an environmental organism, it is associated with dry cow yards in winter. But our research – as well as producer experience from New Zealand and soil culture studies from dry cow paddocks in the USA – suggests summer calving herds need to pay as much attention to S uberis as winter calvers," she says.

The Institutes UK study discovered S uberis infections in both winter and summer calvers. In fact, there was no difference in new infections whether cows were dry on an inside straw-based system or kept on a summer dry cow paddock outdoors. And of cows not receiving dry cow therapy, half those infected with the pathogen in both groups went on to develop mastitis, says Dr Berry.

"S uberis infection is a year-round threat, whatever system you are on. Summer dry cow paddocks present as much of an infection challenge as indoor environments."

Vet adviser Paul Niven, from Schering-Plough, is urging summer calving herds with a cell count problem to obtain an accurate diagnosis. When S uberis is the culprit, he recommends using a dry cow preparation that offers as much protection as possible.

"Widespread S uberis infections are continuing to drive herd cell counts upwards. S uberis remains common because of its ubiquitous nature, its ability to infect cows during the dry period and its ability to persist as a sub-clinical infection."

Mr Niven also says some S uberis strains are more virulent than others and appear able to persist for longer in the environment.

"An accurate diagnosis of the problem is essential for vets to recommend the most effective prevention and control strategies. In herds where S uberis is identified as the primary pathogen causing mastitis, producers should pursue aggressive treatment of clinical cases and review consistently high somatic cell count cows to see whether they are harbouring sub-clinical infection," he advises. &#42