By David Weinstock and Curt Harler

Mastitis is the single greatest foe of all dairy operations and a major quality assurance challenge. Afflicting 20 to 25 percent of cows in U.S. dairy herds, it is the biggest factor in lost milk production.

Between treatment costs and lost production in the current lactation as well as the next, economic losses are significant. “A single mastitis infection costs $250,” says Michal Lunak, a dairy specialist with University of New Hampshire Cooperative Extension.

There are other losses associated with the disease. It has an adverse effect on milk quality and shelf life, as well as on cows’ reproductive and lactation performance, and it can even cause bacterial infections in calves.

There’s another problem mastitis brings; the disease is caused by bacteria – includingStaphylococcus aureus, E. coli, Klebsiella spp. and Streptococcus spp. – so it is treated with antibiotics, which can cause a host of economic and health-related problems made more difficult due to the presence of milk and meat in the human food chain.

Antibiotic downsides

Beta-lactams are penicillin-type drugs used to treat adult cows via teat infusions, and tetracycline is used with more severe infections. The antibiotics used in cattle are of an earlier class than those used with humans, but since they are related, the potential exists for antibiotic resistance being passed along to humans.

There are a number of risks that go hand in hand with drug injection. For example, unsterilized or poorly sterilized needles used on multiple cows can be responsible for disease transmittal. Dull, bent or dirty needles can lead to injuries and infections at the injection site. And if cows are not restrained prior to injection, human injury can result. Done improperly, injections can result in secondary infections. There is even the risk of injecting yourself with drugs meant for cows.

In addition, the milk produced by cows treated with antibiotics must be dumped to prevent its consumption by humans. If detected in milk shipped to plants, costs can be very high for the responsible – or irresponsible – producer.

All of these risks point to a clear need for dairy farmers to seek ways to reduce antibiotic usage and ensure they’re used correctly. Knowing how mastitis gets started in dairy herds will help to lower mastitis infection significantly, and thus reduce the need for the drugs to control it.

Making Treatments Work

Courtesy of Michigan State University.

Courtesy of Michigan State University.

Whether a farmer is treating dairy or beef cattle, a good place to give injections is in the neck. The area recommended by veterinarians, extension specialists and other experts is referred to as “the magic triangle.”

It originated in the beef cattle industry about 30 years ago as part of the industry’s quality assurance program. The idea was to localize injections in the front of the animal, well away from any high-value cuts.

“When doing multiple injections on the same animal, even over a period of several days, alternate them on either side of the neck,” says Julie Smith, UVM Extension dairy specialist.

This is especially useful when administering killed vaccines, which often require booster shots. Smith recommends avoiding vaccination on hot days. “High temperatures will interfere with vaccine response,” she explains.

Clean, dry udders

Cleanliness is a key component of mastitis prevention. Two things farmers should control in dairy barns are manure buildup and water overflow into housing. “Cows should always be clean and comfortable,” says Julie Smith, a University of Vermont Extension dairy specialist.

Lunak agrees. “Whether you use sand or sawdust as bedding, it should be cleaned daily. The area where the udder rests should be cleaned several times a day.”

Don’t depend on post-dips to control infections. “With too much manure, barrier-type post-dips won’t help you,” he says.

The number one strategy for mastitis prevention, Lunak says, is keeping the udder dry. “Number two is keeping the udder dry, and number three is also keeping the udder dry,” he quips.

Wet environments harbor more bacteria, explains Mike Van Amburgh, a professor of animal science at Cornell University. Milking opens the teat end, providing a channel for bacteria to enter. Teat ends don’t close immediately after milking, which makes bringing cows back to dirty stalls an invitation for infection.

Add bedding when needed, he says. “There should be someone running through the barn before the cows come back from milking, cleaning the stalls.”

Allow some time after animals are milked for their teat ends to close. “When she walks back out, give her about 30 minutes or so before she lays down in her bedding,” Van Amburgh advises.

He says using high-quality sand for bedding will help too. “Make sure the sand used for bedding is low in organic debris,” Van Amburgh adds.

Photo by ponsulak/

Photo by ponsulak/

Teat protection

Another key to controlling mastitis is centered on milking practices – specifically the use of both pre-dips and post-dips.

Pre-dips are formulated to combat environmental disease agents cows might have encountered prior to milking. Post-dips are designed to control contagious disease agents cows might be exposed to during the milking process.

 Pre-dipping is the most effective means of reducing mastitis incidence at milking time. Research conducted at both Cornell and the University of Vermont in the mid-1980s with the late Dr. Woody Pankey and others showed that pre-dipping reduced the outbreak of new mastitis infections by half compared to herds that did not pre-dip.

Smith says it’s essential that farmers “select teat dips that have been registered and proven effective.” Effective pre-dip components include iodine, hydrogen peroxide (which foams a bit, providing better teat coverage), sodium chlorite and chlorhexidine, among others. Federal regulations prohibit the use of bleach (sodium hypochlorite).

Dot Perkins, a UNH Extension livestock field specialist, advises, “After dipping, wipe the teats dry with a disposable towel. In a perfect world, changing gloves from animal to animal would be great.”

Perkins recommends using post-dips containing lanolin to prevent udder chapping. When the weather is extremely cold and cows go outside after milking, it may be tempting to skip post-dips. This can help prevent teat end frostbite, but Smith says, “There are products and protocols that can be used in harsh environments to minimize teat end damage. There are emollient dips, powder dips and others. Allowing the dip to dry before cows are let out of the parlor would be nice if there is time in the system.”

Milking machine maintenance and use are also important for mastitis control. Care must be taken to assure proper pulsator adjustment.

Worn-out inflations don’t collapse properly, causing swelling, and in severe cases teat erosion. Lunak says poor cup-to-udder connections can cause bruising and chafing.

Once cows are infected with mastitis, they require special attention at milking time. Ideally, infected cows would be milked last, but this is not always feasible. After an infected cow has been milked, “Take the milking machine, backflush it with a good germicide and clean it before using it on healthy cows,” Van Amburgh says. Smith notes, “According to the Pasteurized Milk Ordinance [PMO], abnormal milk is not to enter the food supply.”

Rules to Live By

Julie Smith, UVM Extension dairy specialist, advocates a “right way” to prevent drug residues in milk and meat. This includes ensuring the right:

  • training for use of all medications and medicated feeds;
  • disease with the right drug;
  • animal;
  • dose/volume;
  • frequency/interval between doses;
  • number of doses;
  • place (intramuscular versus subcutaneous versus intravenous versus intramammary);
  • record-keeping;
  • withdrawal time before shipping milk or animal;
  • attitude: Drug residue prevention in milk and meat is a responsibility we take seriously on the farm.

Before injecting any animal with drugs, be sure to talk to a veterinarian about their appropriate use. Always read and follow the label instructions – a necessary practice, since label instructions can change.

Most importantly, what is the drug’s withdrawal time – how long does it take for the drug to completely leave the animal’s body? Dairy producers who don’t follow the withholding period can lose their Grade A milk licenses after multiple violations. Beef carcasses will be condemned if discovered in a slaughter plant.

Pay special attention to things such as whether or not the drug can be used with pregnant animals – a particular issue with vaccines. Will the drug cause a drop in milk production?

If the drug is labeled for nonlactating animals, that means it can only be used on male animals and heifers that are less than 20 months old or have not had a calf. Smith says, “It cannot be used on dry cows, because they have already freshened.”

Know your vet

Whether you’re using drugs to prevent infection or to clean up an outbreak, a relationship with a veterinarian is necessary to the process.

“Any time a farmer wants to use a vaccine or a treatment on an animal, a veterinarian is required to have a valid veterinarian-client-patient relationship with them,” Smith says.

That means the veterinarian has visited the farm and is familiar enough with the animals to be able to recommend a herd health plan tailored to the farm’s practices, housing and livestock disease history.

Farmers have a role in this too. It is their responsibility to train employees to use and record treatments. The PMO requires that farms keep such records available for inspection for two years. The ordinance is a model regulation. Smith says, “State or local jurisdictions that have adopted the PMO are responsible for enforcement.”

Training should include how often drugs are administered as well as how they’re administered. This applies to the use of drugs and medicated feeds.

Address the issue of when antibiotic use is appropriate. “Once Staph aureus is embedded in the milking tissue, antibiotics aren’t effective anymore,” says Lunak. “Employees need to know things like that.”

Judicious use

Respiratory disease is also treated with antibiotics. Coupled with the significant incidence of mastitis, it is easy to see why animal health professionals are concerned about overuse of antibiotics.

Smith believes quality assurance centers on “judicious use” of antibiotics. “The principle of judicious use attempts to balance the benefits of using antibiotics when necessary and actually helpful with the generation of antibiotic resistance that naturally accompanies antibiotic use,” she says.

The path to quality assurance is not paved only with the judicious use of antibiotics; there are a number of management practices that, when employed well, reduce the amount of antibiotics necessary to keep cows healthy.