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Cows laying in field

Mastitis

Mastitis, an infectious, traumatic or toxic inflammatory reaction of the parenchyma of the mammary gland, is a highly prevalent disease in dairy cattle, and one of the most important diseases affecting the world’s dairy industry.

If left untreated, it can lead to deterioration of animal welfare leading to culling of affected cows, or even death.

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  • Mastitis-causing pathogens include bacteria (mostly Staphylococcus aureus, Streptococcus uberis, Escherichia coli) and non-bacterial pathogens, like mycoplasms, fungi, yeasts, and chlamydia.
    Mastitis can be subdivided into two categories, contagious and environmental, depending on the source of the infectious inoculum.

    The primary source of environmental mastitis is the surroundings in which a cow lives and transmission occurs between milkings while the teat canal is still open.

    The primary source of contagious mastitis, however, is the infected mammary gland quarter and transmission is from cow to cow, by contaminated milking equipment, a nursing calf, or the hands of dairy employees.

    Predisposing factors are insufficient hygiene, dysfunction of the milking apparatus, the presence of teat wounds and the presence of a pathogenic flora in the environment.

  • Mastitis can also be classified as either:
    Subclinical mastitis (organism most commonly associated: S. aureus)
    Milk appears normal and there is no visible sign of inflammation of the mammary gland.
    Diagnosis will be made on somatic cell counts (SCC) and bacteriology.

    Clinical mastitis
    Depending on the type of pathogens involved, fever and depression could be associated with evidence of mammary gland inflammation (redness, heat, swelling, pain), causing chemical, physical and usually bacteriological changes in the milk (from few milk clots to serum with clumps of fibrin).

    Acute mastitis (organisms most commonly associated: E. coli, S. uberis, S. dysgalactiae)
    Clinical signs (fever, depression, loss of appetite) are severe and the gland is swollen, painful, oedematous or very hard;
    Secretions sometimes contain clots or flakes and can be watery, serous or purulent.

    Acute gangrenous mastitis
    (organisms most commonly associated: S. aureus, C. perfringens)
    Anorexia, dehydration, depression, fever and signs of toxemia, sometimes leading to death
    Early in the disease, the gland is red, swollen and warm; within a few hours, the teat becomes cold and secretions watery and sanguineous, leading to necrosis.

    Chronic mastitis
    (organisms most commonly associated: S.aureus, S. uberis)
    Clinical signs of an acute infection from time to time (and no clinical signs for prolonged intervals)
    Secretions periodically contain clots, flakes or shreds of fibrin.

  • Diagnosis may be made on clinical signs (local (swelling of the udder, tender to the touch) and general (fever, depression, loss of appetite) and epidemiology.
    In many cases a reduced milk production can be observed.
    Accurate diagnosis relies on culture and identification of the bacteria from a milk sample taken in an aseptic manner. 
    For subclinical mastitis, the diagnosis will be made on SCC and bacteriology

  • To solve this disease problem, a time-proven five-point control program can be recommended:
    Milking machine maintenance
    Teat dipping
    Early treatment of clinical cases
    Dry cow therapy
    Culling of cows with chronic mastitis

    Once bacteria have invaded the udder and caused mastitis:
    Eliminate bacteria rapidly and effectively by using a targeted antimicrobial, usually an intramammary preparation, following disinfection of the teat;
    Use anti-infectives (parenteral route), depending on the case (vet decision)
    Control inflammation

  • Prevention means minimizing the exposure to mastitis. It includes controlling the environment of the cow, existing infections, and bacteria naturally found on the skin.

    Mastitis could be linked to nutritional issues, mainly VitE/Se deficiency and negative energy balance: so a well balanced diet could help minimize risk of  clinical mastitis .

    Milking routine and hygiene during / between milking are critical points too.

    A product is also available to produce a seal in the teat that provides an immediate and long lasting physical barrier to entry of bacteria and other mastitis-causing pathogens into the udder throughout the dry period. In some cases, an anti-infective treatment will have to be done before the dry period.

  • To date several publications have estimated the costs attributed to clinical and sub clinical mastitis

    Culling
    Mastitis is one of the three major reasons for culling.1
    A cull cow is assumed to cost £420.2

    Diseases related to mastitis
    Cows with ongoing mastitis infection and decreased appetite are prone to develop secondary ketosis and hypocalcemia.
    Mastitis, ketosis and hypocalcemia are all factors that predispose a cow to abomasal displacement.3
    Reproduction
    Cows with mastitis within 45 days after artificial insemination are almost three times more likely to abort in early pregnancy.4

    Milk yield
    Clinical mastitis tends to strike high producing animals in the second or subsequent lactations (= highest production potential). The estimated loss in such animals following clinical mastitis was 1200 kg for the rest of the lactation.5


    Increased labour costs
    Changing of milking units
    Washing extra equipment
    Discarding milk
    Treating the cow
    Additional handling of the cow

  •  1Young, J.A. et al, A summary of the reasons why farmers cull cows. J Dairy Sci. August 1998; 81(8):2299-305
    2Kossaibati M.A  et al.: The Cost of Clinical Mastitis in UK Dairy Herd, MDC Meeting Abstracts 3 2000
    3LeBlanc S.J., Metabolic Predictors of Displaced Abomasum in Dairy Cattle, J Dairy Sci, 2005; 88:159-170
    4Santos, J.E.P.,et al. Animal Reproduction Sci, 2004, 80: 31-45
    5Wilson, D.J., et al, Effect of Clinical Mastitis on the Lactation Curve: A Mixed Model Estimation Using Daily Milk Weights. Journal of Dairy Science, 2004, 87:2073-2084