Mastitis: A common disease affecting animal welfare as well as operating efficiency

Especially during the summer months, the risk of udder inflammation in dairy cows is greatly increased. Mastitis not only causes the worst disease-related economic losses on dairy farms but is also often responsible for the largest medication usage.

Read in this article about causes, different forms and symptoms of mastitis. We also explain how mastitis can be diagnosed.

Multifactorial disease

Mastitis is an infectious, traumatic and toxic inflammation of the lacteal gland. Although the disease is caused by infectious agents, it is a multifactorial disease. This means that pathogenic agents alone are insufficient in terms of causing mastitis. In fact, many other factors play a major role – e.g. stable conditions, feeding and health management of the farm and the associated hygiene. [1] In dairy cows, each quarter may be affected by mastitis independently of the others. [2]

Mastitis results in considerable financial losses, caused by daily milk loss in the current and following lactation. Depending on the time of disease occurrence, a milk loss of 2.5 kg per day or 550 kg per lactation can arise. The earlier mastitis is detected, the smaller the damage.

What are possible causes of mastitis?

Dairy cows have a good endogenous defense and a natural blood-udder barrier, which prevents the entry of pathogens when the immune response of the animal is normal. However, this immune response can be weakened by various factors, causing mastitis. In order for mastitis to develop, the germs must invade the udder, attach themselves and multiply. They also have to come into contact with a host with weak defence mechanisms. [1]
A large number of new infections are due to a lack of stable hygiene or milking errors. Damp bedding, drafts, poor claw care, insufficient milking, dirty milking equipment or feeding errors or feed changes may favor new infection.[1] This indicates that the risks significantly increase when milking or lying in the box, as the teats of the cows come into contact with possible sources of infection.

Which symptoms do cows show, when suffering from mastitis?

A distinction is made between a clinical and subclinical udder infection. They display different symptoms. Another form is acute mastitis.

Subclinical mastitis

  • no externally visible symptoms (for example on the udder)
  • increased cell count in the milk
  • milk is visibly unchanged
  • the affected quarter is possibly slightly hardened or shrunken
  • possibly palpable lumps
  • reduced milk yield

Clinical mastitis

  • obvious inflammatory symptoms of the udder
    • redness
    • heat
    • swelling
    • pain
  • touching is uncomfortable for the cow
  • attendant symptoms
    • high temperature
    • apathy
    • lack of appetite
    • reduced gastrointestinal activity
    • drop in milk yield
  • chemical and physical changes in the milk
    • from a little flocculation to watery milk with fibrin flakes

Acute mastitis

  • most obvious form; symptoms are easily detected
  • obvious symptoms like the ones for clinical mastitis
  • touching is uncomfortable for the cow
  • milking is uncomfortable for the cow
  • milk is interspersed with flakes, watery or purulent
  • increased cell count
  • clinical symptoms are very strong
  • often unable to get up
  • heavy breathing
  • lack of appetite [3]

Mastitis can also become chronic. Chronic mastitis is caused by spontaneous or, despite treatment, a non-healing long-term disease. Affected quarters may shrink and there may be permanent changes which are clinically visible.


There are different methods of diagnosing mastitis:

  • California mastitis test: often used method for indirect determination of the cell count
  • palpation: circumferential growth, heat, painfulness, hardening
  • significant changes in milk
  • checking general symptoms: body temperature, feed/water intake, decline in milk yield
  • milk quality testing: diagnostic tool of great importance; monthly measurements of cell counts show the number of new infections and chronic cases [3]
  • electrical conductivity measurement: in automatic milking, the measurement of electrical conductivity is generally used as a criterion for monitoring udder health; conventional milking systems often also measure this number, and there are also hand-held devices which measure intermittently [4]

When measuring the cell count, you should consider that milk from a healthy udder does not exceed 100,000 cells/ml. If a smear formation is visible, more than 150,000 cells/ml are already present in the milk and if gel is formed there are already over one million cells present.

Research has shown, that diseases in dairy cows occur considerably more often when doubling the milk yield. For example when doubling the yearly milk yield, the probability of mastitis is 2.5 times higher. This is why it is particularly important that cases of mastitis are detected and treated earliest possible.

You want to know more about how smaXtec helps you to detect mastitis earliest possible, read the article Detecting and treating mastitis early with smaXtec.