Mastitis in dairy 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.
dairy cow with gangrenous mastitis . rear quarter

Mastitis in dairy cattle is the persistent, inflammatory reaction of the udder tissue. Mastitis, a potentially fatal mammary gland infection, is the most common disease in dairy cattle in the United States. It is also the most costly to the dairy industry.[1] Milk from cows suffering from mastitis has an increased somatic cell count.

Definition

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

Identification

the quarter with Gangrenous mastitis
A gangrened udder (which sloughed naturally)

This disease can be identified by abnormalities in the udder such as swelling, heat, redness, hardness, or pain (if it is clinical). Other indications of mastitis may be abnormalities in milk such as a watery appearance, flakes, or clots. When infected with subclinical mastitis, a cow does not show any visible signs of infection or abnormalities.[1]

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:

Types of mastitis

Mastitis may be classified according two different criteria: either according to the clinical symptoms or depending on the mode of transmission.

Clinical symptoms
Mode of transmission

Transmission

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

Effects on milk composition

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

Mastitis can cause a decline in potassium 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.[7] Milk from cows with mastitis also has a higher somatic cell count.[8] Generally speaking, the higher the somatic cell count, the lower the milk quality.

Management

Detection

A plastic paddle used in the California mastitis test.

Cattle affected by mastitis can be detected by examining the udder for inflammation and swelling, or by observing the consistency of the milk, which will often develop clots or change color when a cow is infected.[9]

Another method of detection is the California mastitis test, which is designed to measure the milk's somatic cell count as a means for detecting inflammation and infection of the udder.[10]

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. Antibiotics may be systemic (injected into the body), or they may be forced upwards into the teat through the teat canal (intramammary infusion). Cows being treated may be marked with tape to alert dairy workers, and their milk is syphoned off and discarded. To determine whether the levels of antibiotic residuals are within regulatory requirements, special tests exist. Vaccinations for mastitis are available, but as they only reduce the severity of the condition, and cannot prevent reoccurring infections, they should be used in conjunction with a mastitis prevention program.

Control

Practices such as good nutrition, proper milking hygiene, and the culling of chronically infected cows can help. Ensuring that cows have clean, dry bedding decreases the risk of infection and transmission. Dairy workers should wear rubber gloves while milking, and machines should be cleaned regularly to decrease the incidence of transmission.

Prevention

A good milking routine is vital. This usually consists of applying a pre-milking teat dip or spray, such as an iodine spray, and wiping teats dry prior to milking. The milking machine is then applied. After milking, the teats can be cleaned again to remove any growth medium for bacteria. A post milking product such as iodine-propylene glycol dip is used as a disinfectant and a barrier between the open teat and the bacteria in the air. Mastitis can occur after milking because the teat holes close after 15 minutes if the animal sits in a dirty place with feces and urine.

Industry costs

This disease costs the US dairy industry about 1.7 to 2 billion USD each year.[7]

References

  1. 1 2 Department of Animal Science. "Mastitis in Dairy Cows" (PDF). MacDonald Campus of McGill University. Archived from the original (PDF) on July 8, 2003. Retrieved 4 February 2010.
  2. ↑ "Teat Disinfection Facts". NMC. Retrieved 4 February 2010.
  3. ↑ "A Practical Look at Environmental Mastitis". .nmconline.org/. Retrieved 4 February 2010.
  4. ↑ "Mastitis Pathogen Notes: Pasteurella species". nmconline.org. Retrieved 4 February 2010.
  5. ↑ "Mastitis Pathogen Notes: Arcanobacterium pyogenes". nmconline.org. Retrieved 4 February 2010.
  6. 1 2 "Mastitis Pathogen Notes: Proteus species". nmconline.org. Retrieved 4 February 2010.
  7. 1 2 Jones, G. M.; Bailey, T. L. "Understanding the Basics of Mastitis". Virginia Cooperative Extension. Retrieved 4 February 2010.
  8. ↑ Kandasamy S, Green BB, Benjamin AL, Kerr DE. Between-cow variation in dermal fibroblast response to lipopolysaccharide reflected in resolution of inflammation during Escherichia coli mastitis. J Dairy Sci. 2011 Dec;94(12):5963-75. doi: 10.3168/jds.2011-4288. PubMed PMID 22118085
  9. ↑ Laven, Richard. "Mastitis Control and Management: Mastitis Part 4 - Detecting and Treating Clinical Mastitis". National Animal Disease Information Service. Retrieved 27 February 2015.
  10. ↑ "Detection of Mastitis". Department of Animal Sciences. University of Illinois at Urbana–Champaign. Retrieved 27 February 2015.

Further reading

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