If you’re in the dairy business, you’ve no doubt seen the grim results of an acute case of coliform mastitis. The fever; hot, painful udder swelling; grossly abnormal milk; lack of appetite; and shock-like symptoms are difficult to watch and even harder to forget. Often, severe cases like this lead to loss of a quarter, at best; and loss of the animal, at worst. We tend to think of these sporadic cases as the only instances in which we deal with coliform mastitis. But, in fact, about half of all clinical cases are caused by noncontagious environmental organisms, including E. coli, Klebsiella and Enterobacter, which fall together under the umbrella of coliform or gram-negative mastitis.

For years we’ve also presumed that these organisms – whether acute or mildly clinical – would not respond to antibiotics and were best managed with supportive therapy only. Today, that picture is changing.

Early treatment is a must
My colleague, Jorge Noricumbo, is a quality milk manager for Pfizer Animal Health, and is based in California’s Central Valley near Visalia. In his role, he works with dairy owners and employees to provide training and instruction on all aspects of producing high-quality milk. Noricumbo says one of the practices he stresses most is the importance of early detection and treatment of all cases of clinical mastitis.

“Treating at the first sign of udder inflammation creates the best opportunity to achieve both a clinical and bacteriological cure,” he advises. “Often, that requires communication and cooperation between the milking crew and the hospital crew. Protocols for both detection and treatment are essential. Everyone needs to be working together to realize the best possible outcome for the cow.”

The 3, 2, 1 Mastitis Severity Scoring System, which is endorsed by the Milk Quality and Udder Health Committee of the American Association of Bovine Practitioners, provides practical guidelines for evaluating clinical mastitis cases:


Severity score 3 (severe clinical mastitis): Milk or gland abnormalities accompanied by signs of systemic illness, including decreased feed intake, decreased milk production, lethargy, weakness, recumbence, sunken eyes, cold extremities, low-volume diarrhea, fever, tachycardia, dehydration and reduced rumen motility.

Severity score 2 (moderate clinical mastitis): Visibly abnormal milk accompanied by obvious gland inflammation, but no signs of systemic illness. Gland inflammation includes swelling, firmness, heat, pain or redness, with or without a mild decrease in milk production.

Severity score 1 (mild clinical mastitis): Systemically healthy cow with visible abnormalities in the milk and little or no evidence of gland inflammation. Visible abnormalities in the milk are a change in color (yellow, clear, bloody), viscosity (watery, thick), or consistency (flakes, clots).

Severity score 0 (resolved clinical mastitis): Absence of systemic illness and return to visibly normal milk following an episode of clinical mastitis. The gland may remain enlarged or firm but is not red, hot or painful.

Typically, an intramammary mastitis tube is the only treatment needed for scores of 1 and 2. Cows that score 3 would need a mastitis tube; systemic antibiotic therapy; supportive therapy, including fluids (intravenously and/or extra access to drinking water); and anti-inflammatory drugs and pain relievers, based on the herd veterinarian’s advice.

How long to treat?
Achieving a bacterial cure – one that both returns cows to normal milk status and eliminates causative bacteria from the mammary system – should be the goal of any intramammary mastitis treatment protocol. If only a clinical cure is achieved, milk returns to normal appearance, but the bacterial infection may remain in the mammary gland, potentially causing relapses of clinical infections and/or lingering subclinical infections that fuel higher somatic cell counts (SCCs).

“If we’re not treating long enough and simply knocking bacteria back for a temporary, visual cure, then I’d like to say we’re giving that bacteria ‘permission’ to continue to grow in the mammary tissue,” says Noricumbo. “That increases the chances of future clinical flare-ups or chronic cases; can cause subclinical infections that reduce milk production; and will likely elevate individual-cow SCCs.”

The recent announcement of new European Union standards for individual bulk tank SCC of 400,000 cells/mL is just one more reason why producers need to get those bugs the first time.

Promoting treatment success
“Successful treatment that results in a complete cure requires aggressive, effective antibiotic therapy, delivered over a sufficient number of days,” Noricumbo stresses. “There is a big difference between a bacterial organism that is resistant to an antibiotic, and an intramammary infection that does not respond well to antibiotic treatment because the bacteria have become too deeply embedded in the mammary tissue, mainly due to inappropriate or lack of treatment.”

He adds that antibiotic treatment should be merely part of a larger comprehensive plan to prevent coliform mastitis in the herd. His other recommendations include:

• Vaccinating every animal, including heifers, if possible, with an on-label three-shot regimen of a core antigen, gram-negative mastitis vaccine.

• Administering whole-herd dry cow therapy with a broad-spectrum product based on herd culture results and the herd veterinarian’s advice.

• Aseptically administering teat sealant immediately following dry cow treatment.

• Following protocols to limit exposure of the teat end to environmental bacteria, including routine teat dipping and maintaining a clean, dry housing environment.

“Unlike contagious bacteria, you’re never going to be able to completely eliminate cows’ exposure to the environmental bugs that cause coliform mastitis,” he advises. “But there are many things you can do to minimize that exposure, and to quickly eradicate the bacteria when infections do occur.” PD

Gary Neubauer