Pros and cons of different mastitis tests for dairy cows

Mastitis is one of the most prevalent health issues on UK dairy farms – estimated to cost the industry more than £170m/year.

Catching cases early is critical to minimise animal welfare issues and financial losses but there is no one definitive test to detect early cases.

However, new research suggests that technology used for lateral flow and PCR testing to detect Covid-19, could also be beneficial for mastitis detection.

Chris Davidson, from the University of Strathclyde, says these new innovations could help improve detection of mastitis at an earlier stage.

See also: Milk quality issues: Causes and how to reduce the risk

“Though traditional methods are frequently used on-farm, novel new technology could help overcome some of the current limitations,” Mr Davison said.

“Novel technology is useful as it is proactive rather than reactive. If a farmer waits until mastitis symptoms are visible before they test, there is a chance that cows’ welfare will diminish, and milk will be lost.

“Much of the traditional technology is also based on interpretation by a herdsperson, which could lead to inconsistencies with mastitis detection. What’s more, novel technology is economically attractive ­– enabling farmers to better judge whether an animal is sick or not – which has a subsequent effect on milk dumped and medicine use.

“There is no gold standard for testing, as all methods have limitations. However, in my opinion, the most suitable approach is multi-faceted.”

Below, we summarise the different options:

Comparison of mastitis testing methods


What is it?



Traditional technology

Somatic cell count (SCC)

An indicator of milk quality, but also shows the presence of mastitis, as the bacteria breaches the epithelial wall, leaching leukocytes into the milk and therefore raising the SCC

  • Deemed as the industry standard for mastitis detection
  • Produces quantitative data for a more accurate result
  • Usually a lab-based test
  • Reactive diagnosis
  • Typically bulk-sampled
  • Can be costly, both financially and in terms of labour

Enzymatic activity

Assesses proxies (for example, proteins) that typically occur during mastitis

  • Can be done on-farm for a speedy result
  • Lab tests provide effective, reliable results
  • Usually a lab-based test – making it a long process
  • Reactive detection rather than proactive
  • On-farm tests can lack specificity

California milk test

A reagent is added to a sample of milk. If this turns into a thick gel-like mixture, mastitis is present

  • Farm-based test
  • Produces results quickly (usually in less than one minute)
  • Cheap
  • Subjective
  • Imprecise

Milk conductivity

A by-product of sensors already in place for automatic milkers, measuring milk constituents. Electrical conductivity can be a sign of inflammation

  • Increasingly available by default on parlours
  • Farm-based test
  • Can highlight which quarter to sample if it is not obvious
  • Can fluctuate
  • Not specific to mastitis
  • Acute clinical mastitis can be missed as pathogens kill off somatic cells

Novel technology

Lateral flow tests

Similar to human-grade lateral flows, milk samples are added to the test to generate a simple positive/negative result

Can identify specific bacterial, meaning treatment can be more targeted

Project is still ongoing, so data is sparse

Polymerase chain reaction (PCR) tests

PCR tests detect DNA to highlight the presence of mastitis

On-farm kits have recently become available, making the test easier to carry out

Interpretation can be challenging

Cow sensor data combinations

Uses a combination of pedometers, behaviour-monitoring collar and automatic milking systems to detect early signs of animal health issues, which could be because of mastitis

Can give farmers an early indicator that there is an issue with the cow

Not specifically designed for mastitis detection

Chris Davidson was speaking at the British Mastitis Conference on 10 November 2021.