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MilkGenius: Mastitis in Cows

October 10 , 2025
clinical mastitis Cow Comfort mastitis mastitis in cows Mastitis Prevention subclinical mastitis

Mastitis in Cows: Causes, Symptoms, Treatment and Prevention

Mastitis is an inflammation of the mammary gland, usually of bacterial origin, although other factors (mechanical injuries, environmental conditions, viruses, algae, etc.) can also influence the development of inflammation/infection. Bacteria usually enter the udder through the teat canal, releasing toxins that cause inflammation, and possibly damaging the milk-producing tissues, which reduces milk production and quality. Mastitis in cattle can happen at any stage of lactation, even during the dry period but is most common in animals that have calved recently. Despite the emphasis on the prevention of this disease by industry, it still remains the one of the main causes of economic losses on farms, behind only to subclinical ketosis.

Causes of mastitis

Commonly, mastitis in dairy cows occurs due to poor environmental conditions, problems in animal health or deficiencies in herd management. Special attention should be focused on the hygiene and maintenance of the milking equipment, animals and animal housing. There are still other factors that can affect the incidence of the disease such as: diet, other diseases, water quality, animal management, injuries, etc. Therefore, an effective mastitis prevention and control strategy should include not only the treatment of the disease, but also the management of the entire farm.

Signs and types of mastitis in dairy cattle

Mastitis can be clinical (noticeable by observation) or subclinical (no visible signs).

Clinical mastitis

Clinical mastitis can be classified by severity: mild, moderate or severe.

Mild cases, there is only a change in the milk (color, consistency, presence of chunks, blood, etc.) but the animals seem otherwise healthy.

Moderate cases have a change in milk but also show external signs of inflammation such as a swollen or a red quarter that can become quiet painful.

In severe cases the animal as a whole is sick, due to bacteremia or the release of toxins by the dying bacteria. Besides the signs above, the animal may also show signs of systemic disease such as dehydration, severe decrease in milk production, diarrhea, animal not eating and in extreme cases, she may be unable to stand, or some animals will die suddenly.

Subclinical mastitis

Subclinical mastitis is characterized by a mild inflammation of the udder, and the milk appears to have a normal consistency and color, there is no udder or other signs of sickness, and the inflammation is determined only by changes in the composition of the milk and the presence of inflammatory cells. Those inflammatory cells are a great part of the somatic cells.

An increased number of somatic cells, a change in the electrical conductivity of milk and a decreased concentration of lactose are strong indicators in the milk for the diagnosis of subclinical mastitis. Monitoring changes in milk composition and quantity can help identify cows with mastitis effectively and quickly. Modern milking operations increasingly integrate various monitoring systems, including “mini laboratories” that help identify sick animals facilitating the monitoring of animal health. This can be an excellent alternative to tests performed in conventional laboratories, because the data is obtained immediately, there is no need to worry about sampling or sample handling, and the risk of obtaining wrong data due to an improperly collected, handled or mislabeled sample is virtually eliminated. However, not all systems of this type are easy to use, and the cost does not justify its routine use in many farms. Some of them can only be installed on certain milking lines, so a significant number of farms cannot adapt it to their existing equipment, while others lack accuracy and reliability. Many need reagents and routine calibration to assure accurate results.

Losses incurred

It is estimated that the losses currently caused by clinical mastitis can range from $110 to $444 per cow per year depending on the severity and stage of lactation.

Subclinical cases also have a cost. According to studies, elevated SCC is associated with lower milk production, reduced pregnancy rates, and more significant death losses. Milk yield loss increases proportionally to the number of test days with high SCC. It was observed that when SCC in on quarter is at 100 thousand/ml, the productivity from that quarter decreases by 25-35 percent per day, and during the entire lactation – by 10-15 percent. On average, about 650 kg of milk is lost from a cow with high SCC during lactation. And some animals will produce less milk for the rest of their lives due to chronic lesions.

Subclinical mastitis is the most common type of mastitis in farms. Consequently, it is very important to detect subclinical mastitis as early as possible to avoid milk losses and before it becomes clinical. This can be done effectively only with the help of modern diagnostic tools.

How to detect mastitis in cows?

Determination of SCC

One of the most popular tests for the diagnosis of subclinical mastitis is the determination of the somatic cell count (SCC) in milk. SCC counts higher than 200 thousand/ml SCC (composite of all quarters) is the industry cut point to determine mastitis. This test is not always practical and fast, as it requires additional equipment and reagents. When samples are sent to the laboratory, test results are obtained after a few days, which increases time until diagnosis and treatment of the disease, incurring greater losses. There are commercial tests that can be done directly on the farm. Such tests are quite popular, but not always practical, especially on large farms, as each animal must be tested individually. This requires additional labor costs, and the accuracy of the results depends on the thoroughness and attention of the worker. Some manufacturers have developed automated systems for determining somatic cells in milk, but not all milk lines have the possibility to apply them. Such systems are convenient in that employees no longer need to take care of sampling and evaluation of results, saving a lot of time, but require additional, calibration and reagents for conducting tests.

Most SCC detection studies are based on the “California mastitis test” methodology. Active surfactants break down the nuclei of cells in milk, releasing DNA, and causing a change in the viscosity of milk. An indicator is also often used, which changes the color of the mixture due to a change in the pH of the milk. For commercial tests, a few squirts of milk from each quarter are milked on special plates with a reagent, observing changes in the consistency and color of the milk.

Diagnosis of mastitis with MilkGenius HerdLine

Dairy farmers never had the ability to continuously monitor milk quality. But now, the MilkGenius in-line milk analyzer measures fat, protein, and lactose concentrations, along with evaluating changes in the spectrum of each cow’s milk during every milking. This collected data empowers the MilkGenius HerdLine system to provide early warnings of health disorders. Additionally, the insights help to optimize reproductive performance and nutritional management. The ultimate goal of the system is to help dairy farmers maximize the yield of high-quality milk and their profit

Treatment of mastitis in dairy cattle

Undiagnosed or untreated subclinical mastitis can develop into clinical mastitis, which can be seen externally from changes in the milk secretion, the udder appearance and even general signs of systemic disease. Veterinarians can prescribe treatment based on the severity of the disease and the causative agent. Antibiotic therapy is not indicated in all cases of mastitis, and that determination, by the veterinarian, can save time and money. Some cases of subclinical mastitis can be treated with antibiotic therapy (if warranted) and early treatment may be more effective and avoid milk losses. Clinical mastitis may require treatment that involves antibiotics, anti-inflammatory, other systemic medicines and their combinations. Therefore, it is very important to diagnose the disease as early as possible, as this will determine the nature of the treatment. Treating subclinical infections during the dry-off period is more effective than treating them during lactation. An effective form of mastitis prevention in the herd management, is to treat all quarters of all cows with specially prepared, long-acting drugs intended for the treatment during the dry period. With the increased consciousness in the judicial use of antibiotics, the industry realized that not all cows will benefit from this procedure. Being able to determine which animals need or not antibiotic therapy will allow the farm to use a selective dry treatment, treating only the necessary animals, decreasing the use of antibiotics.

Antibiotic treatment must be used in accordance with certain principles:

  • A veterinarian must examine the animal before choosing a treatment.
  • Before prescribing drugs for treatment, the causative agent of the disease should be determined and then the appropriate treatment should be selected.
  • Treatment should not be stopped prematurely at the first sign of normal milk; and one treatment should not be suddenly changed to another without medical advice.

From a practical point of view, it is impossible to completely eliminate mastitis from the herd, but its occurrence can be reduced to a minimum and early detection will decrease losses. Cows with chronic mastitis are a source of mastitis infection for the whole herd. Some animals may do more harm than good to your herd, and you should consider culling, with your veterinarian’s advice:

  • Animals that have had mastitis several times in this lactation or lifetime
  • Animals that have been treated several times (3 or more)
  • Severely damaged or deformed udders and/or teats
  • Infected in the previous lactation and not recovered after treatment during the dry period.


Prevention of mastitis in cows

To prevent mastitis and maintain good milk quality, comprehensive prevention is very important:

  • Hygiene is a must! Dirty cattle, bedding areas, floors, milking machines and areas, improper hand hygiene of milkers create conditions for the spread and reproduction of pathogenic microorganisms.
    • Corrals and walking paths must be comfortable, clean, dimensioned for the needs of the animals, avoiding injuries
  • If the farm has >5% animals with dirty udders, teats and feet, it is an indicator of bad hygiene
  • It is important to check that the teats are healthy, clean and dry before putting on the milking units