Understanding Mastitis

Bovine Mastitis Is Harming Your Cows and Your Profits

Mastitis is the most widespread disease in the dairy industry, costing New Zealand farmers at least NZD$200-400M and farmers globally $40B every year.

It is typically caused by bacteria entering through the teats and infecting the udder tissue, and can either exist as sub-clinical mastitis (no visual signs) or clinical mastitis (redness, clotted milk, swelling).

There are a range of different mastitis types, some that are contagious and can jump from cow to cow (Staph. aureus), and others that come from the environment (E. coli and Strep uberis).

All types of mastitis cause significant losses by:
dairy cow
All types of mastitis cause significant losses by:
  • Increasing your herd somatic cell count, dropping your payout from most processors
  • Reducing milk production by 2.1% for every doubling of somatic cell count over 100,000 cells/ml
  • Forcing you to treat infected cows with antibiotics and withhold their milk, and even cull them if treatment doesn’t work
  • Wasting hours of your time and energy trying to find it by stripping/RMT your herd.

What Is Mastitis, What Causes It, and What Is Clinical vs Subclinical Mastitis?

Mastitis is the inflammation of the mammary gland (udder) in dairy cows and is the most costly disease in the industry. This inflammation can result from infection or injury, but it is most commonly associated with bacterial infections. Mastitis leads to substantial financial losses for farmers due to discarded milk, veterinary costs, increased culling, reduced milk production, and penalties for poor milk quality.

What Causes Mastitis?

Mastitis occurs when microbes, typically bacteria, enter the teat through the teat canal and cause infection. It can also be caused by yeasts, molds, fungi, physical trauma, toxins, and chemical irritants. More than 100 infectious organisms can cause mastitis, but the most common pathogens these bacteria:

1. Streptococcus uberis

  • Gram-positive, primarily of environmental origin, though cow-to-cow transmission can occur.
  • Infections occur mostly during the early dry period and the first six weeks after calving.
  • Highly sensitive to penicillin with good cure rates.

2. Staphylococcus aureus

  • Gram-positive, contagious origin.
  • Spread occurs during milking through milkers’ hands or milking unit liners.
  • Difficult to treat with antibiotics.

3. Streptococcus dysgalactiae

  • Gram-positive, primarily environmental, with potential cow-to-cow transmission.

4. Streptococcus agalactiae

  • Gram-positive, contagious origin.

5. Escherichia coli (E. coli)

  • Gram-negative, environmental origin.

6. Coagulase-negative Staphylococci (CNS)

  • Gram-positive, environmental.
  • Typically causes subclinical mastitis.

7. Corynebacterium bovis

  • Contagious pathogen spread during milking.
bovonic mastitis detection cow

Contagious vs Environmental Mastitis

Mastitis can be classified based on the source of infection as either contagious or environmental.

Contagious mastitis is caused by bacteria that are transmitted from cow to cow, usually during milking. This transmission occurs through the hands of milkers, milking equipment, or any other contact that allows bacteria to spread from an infected udder to a healthy one. These bacteria typically reside on the skin or udder of infected cows, making it crucial to maintain strict hygiene during milking to prevent spread.

On the other hand, environmental mastitis is caused by bacteria originating from the cow’s surroundings, such as bedding, soil, water, or manure.  These bacteria enter the udder when cows come into contact with contaminated materials. Environmental mastitis often spikes during specific periods like the early dry period or immediately after calving, underscoring the importance of maintaining a clean and dry environment to reduce infection risks.

bovonic mastitis injection cow

Clinical vs. Subclinical Mastitis

Mastitis is also classified based on the visibility of its symptoms:

Clinical Mastitis:

  • Characterised by visible changes in the milk and udder.
  • Symptoms include:
    • Rapid onset with heat, swelling, reddening, or hardening of infected quarters, causing pain.
    • Visible abnormalities in milk such as clots, flakes, or discoloration.
    • Systemic signs in acute cases like fever, anorexia, reduced rumination, dehydration, weakness, depression, and noticeable decline in milk production.
    • Gangrenous mastitis can occur, particularly with chronic Staphylococcus aureus infections.

Subclinical Mastitis:

  • No visible changes in the udder or milk.
  • Symptoms include:
    • Reduced milk yield in affected quarters.
    • Periodic episodes of clinical mastitis in affected cows.
    • Elevated Somatic Cell Count (SCC)
    • Chronic infections can persist for entire lactations or the life of the cow, causing prolonged milk production loss.


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Mastitis Calculator

For the average farmer in New Zealand, mastitis monitoring and management costs add up to $80,000 every year. Use the calculator below to find out how much mastitis costs you every year, and how much you could save with Bovonic’s QuadSense.

Disclaimer: This calculator is provided for informational purposes only and is intended to assist farmers estimate the potential costs associated with bovine mastitis on their farms.