Mycoplasma Mastitis: Overview

John H. Kirk, DVM, MPVM
Veterinary Medicine Extension

University of California - Davis

What are mycoplasma?

  • Not bacteria or virus
  • Smaller without cell walls
  • Not affected by antibiotics

    • Historical Viewpoint

  • Late 70’s and early 80’s - Jasper and others from UC-Davis pioneered what we know about mycoplasma today
  • Currently in all major dairy areas - particularly California, New York and Florida, Pennsylvania, Washington, Arizona, Idaho…and more!

    • Prevalence: How much is there?

  • 1-4 % of dairies probably infected - at least one cow
  • Not all states seem to have it
  • 1989 - 1995: 1.2% - 3.1% in large CA cooperative

    • CA survey: 1989-1995
    % Bulk Tanks Tested

    Mycoplasma Species


    at least 11 isolated from milk
  • M. alkalenscens
  • M. agrinini
  • M. bovigenitalium
  • M. bovirhinis
  • M. bovis
  • M. californicum
  • M. canadense
  • M. capricolum
  • A. laidlawii
  • M. untypeable
  • M. others

    • Major mycoplasma species

  • M. bovis - most important by far
  • M. californicum
  • M. bovigenitalium

    • Non-pathogens

  • Acholeplasma laidlawii - often thought to be a contaminate; most often isolated in rainy wet weather

    • Speciation

  • It is important to determine what the species of mycoplasma is….they are not all pathogenic, ie., they don’t all cause mastitis!

    • Route of Infection

    into the herd
  • Introduction of infected animals - cows, heifers, calves, beef heifers, perhaps bulls????
  • Often the route of new infections into the herd can not be determined.

    • Where does mycoplasma live on the dairy?

  • Chronically infected carrier cows
  • Respiratory tract - nose, lungs
  • Reproductive tract - uterus
  • Ear canal - ???impact
  • Environment - manure, urine, water, straw

    • Route of Infection

    into the mammary gland
  • Mycoplasma most always enter into the mammary gland through the teat

    • When do cows become infected?

  • Dry cows
  • Fresh cows
  • Late lactation cows
  • At anytime - milking or dry

    • How do cows become infected?

  • Transfer of mycoplasma from infected cow to another cow during milking
  • Transfer of mycoplasma on infusion tips from an infected cow to another cow
  • Environmental sources especially during wet weather
  • A few cows - mycoplasma moves from other locations in body to the udder

    • Why is more than one quarter often involved?

  • Mycoplasma are very contagious and spread from one quarter to another during milking
  • Some spread via the blood stream to another quarter

    • What type infections do mycoplasma cause?

  • Clinical cases - abnormal milk; high SCC, resistant to treatment, spread high numbers of organisms in milk
  • Subclinical cases - milk appears normal, high SCC, resistant to treatment, intermittent shedding of lower numbers of organisms

    • Individual cow effects

  • Varies with the cows
  • Complete drop in milk production
  • Drop in production with return to near normal
  • Normal production with high SCC
  • Everything in between???

    • Detection methods

  • Culture - bulk tank, fresh cows, clinical cows, high SCC cows
  • Use special media to grow mycoplasma
  • Keep in mind that the numbers of mycoplasma shed into milk varies and so does the ability of the detection method to isolate the mycoplasma

    • Frozen milk samples

  • Freezing does not prevent the sample from being cultured
  • Freeze samples from fresh cows, clinical cases….any cows you may want to check later.

    • How often should I check my bulk tank milk?

  • Once per month is the MINIMUM!
  • Open herds, multiple sources of replacements, purchase milking cows - weekly
  • Large herds - bi-weekly
  • How much "insurance" do you want?

    • Treatment Methods for Cows

  • None are effective!!! Don’t bother to try!

    • Herd Treatment Methods

  • Culling positive cows
  • Segregation into myco strings
  • Maintain control by constant monitoring and surviellance
  • Keep track of new cows and newly fresh cows

    • Herd Treatment Methods

  • Culling positive cows
  • Segregation into myco strings
  • Maintain control by constant monitoring and surviellance
  • Keep track of new cows and newly fresh cows

    • Prevention

  • Closed herd concept
  • Consider ALL new animals on ranch infected!!!
  • Monitoring - early warning system
  • Use several monitoring systems
  • Identify infected cows early
  • Be very careful and clean when infusing cows

    • The "Dreaded" Mycoplasma

  • It can be controlled
  • Develop a plan…write it down, each step
  • Work with your veterinarian…they do more than just preg check your cows
  • You are in charge! Take charge!

    • Got "Quality" Milk???

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