Recognizing the ‘itis’ Part of Mastitis

Get cows back into milk faster by letting them clear mild mastitis cases on their own.

Identifying a case of mastitis can mean a five-day waiting period – or more – before cows are eligible to return to milk. Every day of discarded milk means lowered productivity and profitability. However, progressive dairies around the country are relying more on diagnostics and less on treatment regimes.

“When you identify and treat mastitis, you’re observing inflammation and not necessarily an active infection,” said Mark van der List, MPVM, BVSc, senior professional services veterinarian with Boehringer Ingelheim Animal Health. “Signs of inflammation may persist for three to five days after the infection has ended. Basing intramammary antibiotic treatment solely on signs of inflammation can lead to overuse of antibiotics.”

Identifying eligible cases

The cow’s immune system can be very effective in clearing the infection, van der List noted. Typically, producers identify cases of mastitis in the milking parlor by tell-tale swollen quarters and clotted or discolored milk. Then, cows receive a two- to seven-day course of antimicrobials.

“The usual practice is to see inflammation and treat it as an active infection, but on-farm cultures provide a way of better advising whether antibiotic therapy is needed or not,” he advised.

An on-farm lab can receive results in about 24 hours. Cases typically fall into one of three groups, with roughly one-third of cases in each:

• Gram-positive bacteria present, which benefits from being treated with antimicrobials

• Gram-negative bacteria present, which does not benefit from being treated with antimicrobials

• No growth, which indicates no bacteria is present and the cow has cleared the infection on her own and would not benefit from antimicrobial treatment

“A majority of studies have shown no benefit to treating gram-negative mastitis with intramammary antibiotics,” van der List said. “One-third of cases will likely show no growth. In those cases, you obviously don’t want to treat. Basically, you can reduce antibiotic usage by two-thirds because all you’re treating are the gram-positive cases.”

Committing to staffing

This approach could save producers in treatment costs and help get cows back into saleable milk faster.

“Not treating gram-negative and no growth infections can still result in a faster integration into the herd,” van der List noted. “As soon as the milk looks normal, cows can contribute to saleable milk.”

On-farm cultures are more amenable to progressive dairies that can staff an on-farm lab.

“It’s hard to maintain because you have to have someone who’s doing these diagnostics on the farm,” van der List said. “This approach is not widely accepted, but it’s good practice and minimizes antibiotic usage. We want to use antibiotics where they are going to be effective and where it has an impact.”

Stop cases before they start

Farms of all sizes can feel confident in their approach to preventing mastitis. In recent years, van der List noted that cases of contagious mastitis are decreasing because of widely accepted practices like ensuring cows have clean pens, using good milking techniques, ensuring milking machines are correctly functioning, using teat dips, adequately stripping cows and culling chronic cases.

“Across all sizes of dairies, there’s been a shift from contagious mastitis – basically Staphylococcus – to environmental mastitis. That means the most likely source of infection is no longer another infected cow spreading the bacteria at milking time. Now, the bugs are environmental. The bugs are everywhere, which means it’s important to clean cow pens and do a good job precleaning teats before milking.”

Image credit: istockphoto.com/shaunl