Mastitis in dairy cow with severe inflammation of the mammary gland and udder tissue

Mastitis in dairy cows

Mastitis is a disease which causes severe inflammation of the mammary gland and udder tissue of dairy cattle. It usually occurs as an immune response to bacterial invasion of the teat canal and can also occur as a result of chemical, mechanical, or heat injury to the udder. Mastitis can occur as easily recognisable clinical mastitis, or mastitis can exist within the herd in its subclinical form, with few, if any, symptoms present. This page is intended to provide a better understanding of the challenge of controlling mastitis for dairy farmers. Always consult your own veterinary surgeon for diagnosis and advice.

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What is mastitis?

Mastitis is an infection of the udder caused predominantly by the ingress of bacteria. The infected udder produces less milk and milk of a lower quality. The risk of the disease is increased when housing and bedding standards are below par or when the recommended milking parlour hygiene standards aren’t maintained. The onset of mastitis can also be exacerbated by suppressed immunity.

Acute cases can be fatal, and even in treatable cases there is a significant chance of permanent damage which will not only affect the current lactation but also subsequent lactations.

How to recognise clinical mastitis

Symptoms mastitis

The most obvious symptoms of clinical mastitis are mild to severe swelling of the udder which will also feel excessively warm to the touch and will be red in appearance. The udder will also cause the cow discomfort when touched. In severe cases, the cow’s body temperature will increase and the milk that she produces will have a water appearance and may contain flakes, clots, pus or blood.

Other symptoms of mastitis can also include reduced milk yield, lack of appetite, sunken eyes, a reduction in mobility (due to udder pain or simply feeling unwell) and signs of diarrhea and dehydration.

In severe cases of acute, clinical mastitis the cow may appear very ill indeed. In contrast, subclinical mastitis may not be immediately obvious and can result in few symptoms other than a higher than normal somatic cell count.

Veterinary surgeon about limiting the disease's extent of Mastitis

"Milking routine hygiene, housing and bedding management and the culling of chronically infected cows can all help to limit the disease’s extent, as can an effective dairy cow diet."


Arnout Dekker, Veterinary surgeon, Phibro


What causes mastitis in a cow?

The predominant cause of mastitis is a bacterial infection of the teat canal. It can also be caused by physical, chemical or heat damage to the udder tissue.

Poor hygiene – either in the milking parlour or cubicle housing – is the number one cause of infection: milking equipment which isn’t properly cleaned or maintained is a key source of infection, as are dirty and wet cubicles.


What are the consequences of mastitis?

A cow suffering from mastitis will produce milk of a lower quality (high somatic cell count) and can pass the infection to other cows. The chance of a complete udder recovery in an infected animal is limited, resulting in reduced milk production during the remainder of the current lactation and subsequent lactations. Affected cows are also likely to be less fertile and have a greater chance of premature birth.

The control and treatment of mastitis is one of the largest costs to the dairy industry and is also a significant factor in dairy cow welfare. Losses arise from:

  • The disposal of contaminated milk
  • Reduced milk yields due to illness and permanent udder damage
  • Higher susceptibility to other diseases
    Negative effect of fertility
  • Additional labour and veterinary costs associated with treating affected cows
  • Premature culling and reduced longevity
Julian sander-1

“The best part of my job is helping farmers. Reducing the use of antibiotics in dairy herds is one of my biggest goals”


Julian Sander, Dairy Technical Specialist, Phibro


How to prevent mastitis?

Milking routine hygiene, housing and bedding management and the culling of chronically infected cows can all help to limit the disease’s extent, as can an effective dairy cow diet.

The effective management and control of mastitis is reliant upon instigating and maintaining strict levels of hygiene at all stages in the dairy cow’s regime in order to keep teats clean and healthy: this not only applies for lactating cows, but also for heifers and dry cows.

  • Cubicles and loose housing facilities should be kept as clean possible, with fresh bedding applied regularly to reduce the risk of cross-contamination from one cow to the next.
  • Cattle should be handled carefully and calmly in order to reduce stress and to avoid cows being rushed through areas where muck could cause excessive udder soiling.
  • Milking equipment should be kept meticulously cleaned and should be regularly checked for correct functioning to prevent physical teat damage. Over-milking should also be avoided in order to safeguard teat and udder health.
  • Field and cow track conditions should also be considered: excessively wet or muddy conditions will increase the potential for udder soil and teat infections.

Learn how to support the immune capability of dairy cows for optimised health and production.


Treatments for mastitis

The treatment and management of mastitis, including drying off protocols, surely represents the largest contributor to the total of antibiotic use in dairy production. This is therefore a priority area for the development and implementation of alternative strategies that support animal health and milk quality while minimizing the use of antibiotics.


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We’ll carry out a detailed review to make sure the changes we’ve put in place are working effectively and, where necessary, provide additional support and advice to enable your herd to continue to improve.

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