Mastitis caused by Klebsiella used to be thought of as only a problem with sawdust bedding. No more.
The bug, and its lethal consequences, has taken up residence in all sorts of bedding types—even sand if it is high in organic matter. “It’s not just sawdust-related; it is everywhere on a dairy,” says Pat Gorden, who serves as the herd health veterinarian for the Iowa State University dairy herd.
And it’s a nasty little bug. “With Klebsiella, you have a higher risk of culling and death. It is a very bad cousin of E. coli,” he says.
This past year, the 400-cow Iowa State herd had 33 cases of Klebsiella in 28 cows. Klebsiella accounted for about half of the dairy’s clinical mastitis. Of the 28 cows infected with Klebsiella, 16 cows (or 57%) were either sold or died as a consequence of the infection.
“In our experience, cows may not appear real sick on the first day of infection,” Gorden says. “But by the second day, they are very sick, with some being down and a high percentage die.”
In Iowa State’s case, cows with three or more lactations were more prone to Klebsiella infection. “We had very few first-lactation cows infected during the past year,” he says.
Even if cows survive a clinical bout of Klebsiella, they’ll likely produce much less milk the remainder of the lactation. In a Cornell University study done a few years ago, healthy cows averaged about 75 lb. per day during the last two-thirds of their lactations.
Cows with clinical Klebsiella mastitis averaged about 60 lb. per day, and production never rebounded to the pre-infection lactation curve. Cows with E. coli clinical mastitis also dropped to the 60 lb. per day level immediately after infection but eventually returned to more normal lactation curve output.
Unlike E. coli, which typically infects cows during the dry period, the majority of Klebsiella cases occur during lactation. And as the milk production data suggests, the effects of Klebsiella clinical infections are much longer in duration.
Klebsiella bacteria are encapsulated and, like E. coli, produce a toxin that makes cows sick. However, compared to E. coli, Klebsiella cows are often more severely affected. As a result, antibiotics are not always effective. Cornell University has reported good treatment success with intramammary ceftiofur in mild and moderate cases, while in a side-by-side comparison at Iowa State, they did not, according to Gorden.
“However, we did not do a controlled study like the Cornell work, so our results may be skewed as a result,” he says.
The best approach is prevention. “Bedding must be clean and dry, and teat sanitation is critical,” he says.
Bedding should be 95% dry matter or higher, and organic matter should be less than 3%, which is really only possible with sand.
“Less than 5% is good, and numbers above that are difficult to make work without a concentrated effort at managing cows beds,” Gorden says.