Klebsiella is a gram-negative bacteria that can cause severe clinical mastitis in dairy cows. Mastitis caused by Klebsiella commonly results in abnormal milk; hard, swollen, painful quarters; and sick cows that sometimes die. If they survive the illness, cows are often culled due to low milk production. In a study performed by Iowa State University, only 43% of cows with Klebsiella mastitis stayed in the herd after recovering from the disease. The remaining 57% either died or were culled.
Cases of Klebsiella mastitis typically occur equally throughout the lactation cycle, meaning there is a similar number of infections in the first 100 days in milk (DIM) as the second 100 and third 100 DIM. On many farms, Klebsiella mastitis occurs more frequently in older cows (third lactation or higher) compared to younger animals.
Cows that survive an initial bout of Klebsiella mastitis may develop chronic mastitis. Their milk will look normal but somatic cell counts (SCC) will be high, and multiple cases of mastitis due to the bacteria may occur later. These chronically infected cows should be segregated, milked last and culled when possible.
Cows shed Klebsiella intermittently in their manure. Research by Cornell University showed that 80% of fecal samples collected from healthy dairy cows contained Klebsiella. Fecal shedding of Klebsiella can result in contamination of the entire farm, including freestalls, walkways, the parlor, waterers and holding pens. Wherever there is manure on your farm, Klebsiella is likely to be present.
Cases of Klebsiella mastitis usually peak during the summer months (June – September). This is because:
- The bacteria live longer and reproduce better in warm, humid weather, resulting in more Klebsiella in the cows' environment.
- Heat stress can lower cows’ immune defenses which make them more susceptible to the bacteria.
This year has been particularly challenging for dairies in the northeastern U.S. with Klebsiella mastitis. It’s thought that the high summer humidity levels in this geography played a major role in these infections.
The foundation of any plan to control Klebsiella mastitis must be to decrease the amount of Klebsiella in the cow’s environment and prevent direct contact of teats with manure. This article describes some common ways Klebsiella is transmitted from the environment to teats and strategies on how to prevent Klebsiella mastitis cases on your farm.
Milking parlor
Improperly laundered cloth towels can be a source of Klebsiella. Towels should be washed using hot water and detergent and thoroughly dried before use. Chlorine bleach can be added in the rinse cycle to help kill bacteria. It’s imperative not to overload the washer during the laundering process.
Milking equipment performance should be evaluated on a routine basis. Claw vacuum is especially important. Too high of levels can cause edema to build up in the teat during milking which can greatly delay closure of the teat canal when the cow is back in the pen. An open teat canal allows Klebsiella from the environment to enter the udder.
Reducing water use in the parlor can help prevent "splash" from occurring. Splash is when manure-contaminated water splatters onto cows’ teats, udders or legs. It can occur when deck manure is sprayed toward cows that have just exited the parlor stalls or when butt pan channels are flushed while cows are still in the parlor. Using a short-handled squeegee to move manure on the immediate deck area during active milking and only hosing the entire deck between groups when no cows are present helps prevent splash. Also, producers should set a regular schedule to flush butt pans between groups. Be cautious when using high-pressure hoses which can easily aerosolize pathogens and send them toward cows with open teat canals.
Cow traffic areas
Manure and manure-contaminated water in alleyways and holding pens are significant sources of Klebsiella, especially during summer months when sprinklers and soakers are used for cow cooling. Controlling the splash of this manure onto teats, udders and legs can help prevent cases of Klebsiella mastitis. Cows can easily carry the manure on their feet and legs into stall beds, and once they lie down, this manure may be transferred to their teats.
To help control manure levels, holding areas and return lanes should be scraped multiple times during milkings if manure is accumulating. Alley scrapers must be functioning properly so that manure is not left next to stalls or in the middle of alleys. Unused or poorly maintained footbaths in return alleys and pens can accumulate manure and serve as a source of Klebsiella.
Fast cow movement when groups are brought to the parlor also can be a large risk factor for splashing manure onto teats, udders and legs. To decrease this risk, it’s recommended to standardize exactly how cows are moved to be milked. For example, everyone who fetches cows should swing the same gates and move the same way through the pen. They should make the same sounds and rake the backs of stalls in the same order. When cows know what to expect, they are more likely to walk calmly and quietly to the parlor, which reduces the risk of splashing manure.
Freestall management
Proper cow positioning is key to lowering Klebsiella counts in the back one-third of stalls. If cows lie too far forward or at an angle, when they defecate, their manure will land in the stall bed instead of going into the alleyway. Producers should identify why cows are lying improperly in the stalls and then work to fix the problem. This could involve adding a brisket pipe or making sure stalls contain enough bedding.
Any bedding material, including new sand, can quickly become contaminated with Klebsiella once placed in the stall. To keep stall bedding clean and dry, it should be groomed and refilled often. Manure should be scraped from the backs of stalls at each milking. Bedding should be stored under a cover to keep it dry while waiting to be added to stalls.
All unused and used bedding can be tested for Klebsiella. Current guidelines state that all unused and used bedding (new and recycled sand, recycled manure solids, shavings, straw, etc.) should not contain any Klebsiella organisms. If new sand contains Klebsiella, check for dirt contamination which can occur during harvest or storage on-farm.
Teat disinfection
Teat disinfection, both before and after milking, is critical in reducing cases of Klebsiella mastitis. Pre-dipping helps clean and disinfect teats prior to milking unit attachment. Dip should thoroughly cover the entire teat end and barrel and stay on for a minimum of 30 seconds before it’s removed.
Research shows that pre-dipping doesn’t kill all Klebsiella on dirty teats. If teats are dirty when cows enter the parlor, more bacteria will be present on them after the pre-milking disinfection routine is completed. Simply put, if teats start dirtier, they will end dirtier.
Teat end cleanliness prior to milking unit attachment is an important area to monitor when trying to prevent Klebsiella mastitis. If teat ends are dirty when the teat canal is opened to milk, the likelihood of Klebsiella entering the udder is much greater. Milkers need to be trained that wiping teat ends requires a different hand motion compared to wiping the teat barrel. Monitoring the cleanliness of teat ends on a consistent basis helps reinforce the importance of this critical step.
If teat ends were not effectively cleaned before milking unit attachment, post-dip can help kill the remaining bacteria on the teat end. Post-dip can also support good teat skin condition due to the emollients it contains. Be cautious of some barrier dips due to the increased amount of time they require to dry. If teats are tacky when cows lie down in stalls, bedding will stick to them, making them much harder to clean at the next milking.
Teat skin health
We have observed a relationship between herds with dry teat skin (scaly, flaky and rough) with open lesions (cracks, cuts, incisions and burns) and Klebsiella mastitis. It is believed that these teats are colonized with more bacteria than teats with healthy skin. Also, dry teats with lesions are more difficult to disinfect before milking, which results in more bacteria on the teat end at the time of milking unit attachment.
Exposure to cold and windy weather, excessive moisture in stall bedding, and some post-dips and bedding additives can all lead to dry teat skin. Using a high-emollient post-dip that completely covers the teat end and barrel can help treat and prevent dry teats with lesions. Teat skin health should be evaluated while cows are in the parlor using a good light source so abnormalities are easier to spot. The National Mastitis Council recommends checking at least 80 cows or a minimum of 20% of animals in herds larger than 400 cows.
Vaccination
Research performed at the Iowa State University dairy farm demonstrated that cows given a commercially available Klebsiella vaccine (Vaxxon SRP Klebsiella) had 76% fewer cases of Klebsiella mastitis and 55% fewer cases of mastitis caused by any coliform bacteria than cows given a placebo. Vaccinated cows also had a significant increase in milk production and decrease in SCC. Whole-herd vaccination followed by two or three doses of vaccine each lactation is recommended. Producers should work with their veterinarian to determine if vaccinating for Klebsiella mastitis is right for their herd.
Fecal shedding, gut health and nutrition
A current theory about fecal shedding of Klebsiella is that cows are not chronic carriers of the bacteria but instead are frequently exposed to Klebsiella through consuming feed and water contaminated with manure. Once inside the cow, bacteria pass from the rumen through the GI tract and are eventually shed in feces.
Subacute ruminal acidosis (SARA) and rations with higher starch levels may increase Klebsiella shedding in manure. During heat stress, cows are at an increased risk of developing SARA because they often eat erratically, sometimes engaging in slug feeding and sorting, which can cause changes in rumen pH. Also, during heat stress, cows drool more which decreases the amount of saliva available to buffer the rumen. Currently, we don’t know the true impact of these factors on Klebsiella mastitis, but they may contribute to the increased number of cases seen in summer months.
Although we don’t fully understand how, why or when cows shed Klebsiella in their manure, it is a sound approach for overall cow health to support proper rumen fermentation and gut health and prevent SARA. This can be accomplished through consistent ration formulation, mixing and delivery; feeding high-quality ingredients devoid of mold, mycotoxins, wild yeast and bacteria; and ensuring proper feeding management. Additionally, there are a variety of feed additives marketed for use in dairy cows for these purposes. Producers should discuss these options with their nutritional consultants and veterinarians.
