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Canadian Bovine Mastitis Research Network
 

All about Mastitis I Treatment and Antimicrobial Resistance

Curing and Protecting I Well tought decision

Is It Preferable to Treat All Cows at Dry-Off?
 

Which cows need treatment and which cows need prevention, without culturing every cow before she goes dry? There is no scientific answer available for that yet, but you do have a lot of information readily available - cow’s SCC throughout lactation, clinical mastitis history, previous culture results, and possibly a CMT result before going dry. But no one of these pieces of information alone can answer the question...

When long acting antibiotics were made into dry cow mastitis tubes over 50 years ago, the recommendation was to treat every quarter of every cow at the time of drying off. The dry period represented then, and still does today, the best time to administer antibiotics for an extended period of time with the least fear of antibiotic residues. Also, 50 years ago the most common causes of mastitis were primarily by Streptococci and Staphylococci. A lot has changed since then. For example, Streptococcus agalactiae is easily eradicated and it is hardly ever cultured from routine samples. There is increased concern in the industry and in the public about antibiotic residues and resistance developing from routine use of antibiotics in food animals. Having that said, treating dry cows at dry off remains an important component in a complete udder health control and management program. The issue really becomes, do we need to treat all cows, or do we just need to treat cows that are infected or are at a high risk of mastitis? Probably the latter of the two is the preferable choice.
 
Curing and protecting

The goal of the dry period is to have as few quarters infected at the time of calving as possible. To reach this goal, two things must happen. All infected quarters at drying off need to be cured in the dry period, and uninfected quarters need to be protected from getting new infections. The only reliable and proven means to cure mastitis in the dry period is with antibiotics. Some cure much easier than others, and certainly not all are cured (think of Staph aureus!). However, an infected quarter, or even an uninfected quarter in the same cow, are more likely to be infected when the cow calves, if the cow was not treated with dry cow antibiotics. Spontaneous cures (curing without treatment) do occur, but this is not a reliable enough event to try to manage.

There are alternatives to antibiotics to prevent uninfected quarters from becoming infected. The most notable are internal teat sealants, as they have been shown to be as effective as antibiotics for prevention and decreasing mastitis in the next lactation. When inserted and used properly, sealants should prevent any bacteria from getting into the quarter for the entire dry period. Currently available dry cow antibiotics are not effective against all bacteria, and they also do not last for the entire dry period.

Well thought decision

The decision still becomes, which cows need treatment and which cows need prevention, without culturing every cow before she goes dry. There is no scientific answer available for that yet, but you do have a lot of information readily available. Consider the cow’s SCC throughout lactation, her clinical mastitis history, previous culture results, and possibly a CMT result before going dry. No one of these pieces of information alone can answer the question. Some producers wanting to try selective dry cow therapy, or those in the organic industry, have all ready done a lot of research and trial and error themselves.

So, it is certainly preferable to treat all infected cows at drying off. If you can decide with your veterinarian or other consultants, which cows are likely uninfected or low risk, you can concentrate on prevention and achieve the same goal. In this case, using devices such as internal teat sealers are recommended as opposed to doing nothing to the cow, as untreated & unprotected cows have a high risk of new infections in the dry period.
 
Source: Dr Randy T. Dingwell, DVM, DVSc., Holdrege Veterinary Clinic, Holdrege, Loomis, Nebraska. 2007.
 




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