Mastitis in cattle

Gangrenous mastitis in a cow after 10 days. Green arrow indicates complete necrosis of the teat. Yellow arrows indicate the limits of the gangrenous tissue, but the necrotic area is not well delimited on the upper part of the udder.

Mastitis is a persistent, inflammatory reaction of the udder tissue. This potentially fatal mammary gland infection is the most common disease in dairy cattle. It is also the most costly to the dairy industry.

Definition

Mastitis occurs when white blood cells (leucocytes), are released into the mammary gland, usually in response an invasion of bacteria of the teat canal. Milk-secreting tissue, and various ducts throughout the mammary gland are damaged due to toxins produced by the bacteria. Mastitis can also occur as a result of chemical, mechanical, or thermal injury.

Identification

This disease can be identified by abnormalities in the udder such as swelling, heat, redness or pain. Other indications of mastitis may be abnormalities in milk such as a watery appearance, flakes, clots, or pus.

Mastitis-causing bacteria

Bacterial cells of Staphylococcus aureus, one of the causal agents of mastitis in dairy cows. Its large capsule protects the organism from attack by the cow's immunological defenses.

Bacteria that are known to cause mastitis include:

• Staphylococcus aureus
• Staphylococcus epidermidis
• Streptococcus agalactiae
• Brucella melitensis
• Corynebacterium bovis
• Mycoplasma (various species)
• Escherichia coli, (E. coli)

Transmission and prevention

Mastitis is most often transmitted by contact with the milking machine, and through contaminated hands or materials.

Types of mastitis

• Contagious mastitis
• Environmental mastitis

Effects on milk composition

Serous exudate from udder in E. coli mastitis in cow (left), in comparaison to normal milk (right)

Mastitis can cause a decline in [[potasium] and lactoferrin. It also results in decreased casein, the major protein in milk. As most calcium in milk is associated with casein, the disruption of casein synthesis contributes to lowered calcium in milk. The milk protein continues to undergo further deterioration during processing and storage.

Industry costs

This disease costs the US dairy industry about 1.7 to 2 billion USD each year.

Treatment

Treatment is possible with long-acting antibiotics, but milk from such cows is not marketable until drug residues have left the cow's system.

Control

Practices such as good nutrition, proper milking hygiene, and the culling of chronically infected cows can help in the control of this disease.

See also

• Mastitis in domestic animals
• California mastitis test
• Somatic cell count

Further reading

• Harmon, R. J. 1994. Physiology of mastitis and factors affecting somatic cell counts. J. Dairy Sci. 77:2103-2112.
• Jones, G. M., R. E. Pearson, G. A. Clabaugh, and C. W. Heald. 1984. Relationships between somatic cell counts and milk production. J. Dairy Sci. 67:1823-1831.
• Myllys, V., and H. Rautala. 1995. Characterization of clinical mastitis in primiparous heifers. J. Dairy Sci. 78:538-545.
• National Mastitis Council. 1996. Current Concepts of Bovine Mastitis, 4th ed., Arlington, VA.

External links

UC Davis fact sheet