Mastitis: causes, symptoms, prevention, and treatment

Cause

Mastitis is the inflammation of the mammary gland and udder tissue.

It usually occurs as an immune response to bacterial invasion of the teat canal by variety of bacterial sources present on the farm (commonly through bedding or contaminated teat dips), and can also occur as a result of chemical, mechanical, or thermal injury to the cow’s udder.

Mastitis is a multifactoral disease, closely related to the production system and environment that cows are kept in. Mastitis risk factors or disease determinants can be classified into three groups: host, pathogen and environmental determinants.

Symptoms

Subclinical: Few symptoms of subclinical mastitis appear, although it is present in most dairy herds. 

Somatic cell counts measure milk quality and can be used as an indicator of mastitis prevalence. 

Clinical mastitis: The most obvious symptoms of clinical mastitis in the udder are swelling, heat, hardness, redness or pain. 

Milk takes on a watery appearance, flakes, clots or pus is often present. 

A reduction in milk yields, increases in body temperature, lack of appetite, and a reduction in mobility due to the pain of a swollen udder are also common signs. 

Treatment

NSAID are widely used for the treatment of acute mastitis. Aspirin, flunixin meglumine, flurbiprofen, carprofen, ibuprofen, and ketoprofen have been studied as treatments for experimental coliform mastitis or endotoxin-induced mastitis. Orally administered aspirin should be used with caution in acute coliform mastitis because it may lead to severe rumen atony.

Prevention

1. Hygienic teat management: which includes good housing management, effective teat preparation and disinfection for good milk hygiene, teat health and disease control.
2. Prompt identification and treatment of clinical mastitis cases: including the use of the most appropriate treatment for the symptoms.
3. Dry cow management and therapy: where cows are dried off abruptly and teats are cleaned scrupulously before dry cow antibiotics are administered, including the use of teat-end sealants if appropriate.
4. Culling chronically affected cows: cows that become impossible to cure and represent a reservoir of infection for the whole herd.
5. Regular testing and maintenance of the milking machine: with regular, recommended teatcup liner replacement and milking machine servicing and attention paid to items which must be checked on a daily, weekly or monthly basis.
6. Good record keeping: of all aspects of mastitis treatment, dry cow therapy, milking machine servicing, Somatic Cell Counts and Bactoscan results, and clinical mastitis cases.

Diagnostics

It’s important to identify the pathogen causing the mastitis infection because different categories of pathogens require different mastitis management strategies. Without taking the time to determine a diagnosis, there is no way to know if a given antibiotic will work. However, once you know the pathogen, a dairy farmer can work with his or her veterinarian to develop a mastitis control program that fits your specific operation.

Consider your diagnostic options based on the needs of your dairy farm.

Overview of Testing Methods

Test	Identification of mastitic milk	Identification of pathogen	Fast	Reliability	Test location	Milk sample type
California Mastitis Test	✓	✗	✓	✓	Farm	Fresh milk
Somatic cell count	✓	✗	✓	✓	Lab	Fresh milk
ELISA	✗	✓	✓	✓	Lab	Fresh, Frozen, Preserved
Bacterial culture	✓	✓	✗	✓	Lab	Fresh
Multiplex PCR	✓	✓	✓	✓✓	Lab	Fresh, Frozen, Preserved

Test	Principle
California Mastitis Test	Detergent lyses white blood cells (leucocytes) in milk sample, resulting in viscosity of the fluid. This is a measure for severity of infection.
Somatic Cell Count	Counting of leucocytes in a milk sample, either under a microscope or using automated cell counting systems (flow cytometry).
ELISA	Detects antibodies instead of pathogen; infection may no longer be active.
Bacterial culture	Milk sample is streaked on culture plates. Viable pathogens form colonies that are counted.
Multiplex PCR	Amplification and detection of nucleic acid of mastitis-causing pathogens. Screening for multiple pathogens in one run. Indicates active infection. Pathogens do not need to be viable.

Submitting a clean milk sample to the laboratory is critical to a successful pathogen diagnosis. Follow these steps:

1. Clean the udder from visible dirt
2. Prevent kicking
3. Wash your hands
4. Clean the teat end with 3 clean swabs dipped in 70% alcohol disinfectant
   a. If the teat end is in poor condition,     more cleaning may be needed
5. Open the milk tube corn and keep it clean in your palm
6. Milk the sample keeping the tube in horizontal position
7. Close the cork immediately
8. Add markings like cow number, quarter and date on the tube
9. Important: only one quarter to one tube