Merck Manual

Please confirm that you are a health care professional


Mastitis in Large Animals


Ronald J. Erskine

, DVM, PhD, Michigan State University

Last full review/revision May 2020 | Content last modified May 2020
Topic Resources

Mastitis, or inflammation of the mammary gland, is predominantly caused by bacterial pathogens and occasionally mycotic or algal microbes. Pathologic changes to milk-secreting epithelial cells from inflammation decreases function, ie, milk production. Depending on the pathogen, deceased milk production may continue into further lactations, which reduces productivity and, for beef and other meat-producing animals, potential weight gain for suckling offspring. Although most infections result in subclinical local inflammation or mild clinical cases, more severe cases can lead to agalactia or even profound systemic involvement, including death.

Mastitis has been reported in almost all domestic mammals and has a worldwide geographic distribution. Climatic conditions, seasonal variation, bedding, housing density of livestock populations, and husbandry practices, such as milking protocols for dairy animals, affect the incidence and etiology. However, mastitis is of greatest frequency and economic importance in species that primarily function as producers of milk for dairy products, particularly dairy cattle and goats. (Also see Udder Diseases.) Mastitis in sows is discussed elsewhere.

Others also read

Also of Interest


View All
Fractured os penis (ultrasound)
Fractured os penis (ultrasound)
Ultrasound of a fractured os penis (visible discontinuity of the os).