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Mastitis Case Studies

Mastitis Treatment and Control


This resource describes the approaches for treatment and control of mastitis.

Mastitis Treatment

Antibiotic treatment: Typically when clinical mastitis is detected, the cow is milked out and then given an intramammary infusion of antibiotic, ie. infused directly into the infected gland. Clinical mastitis symptoms are indicated in the Mastitis Clinical Syndromes resource, but most often are recognized by themilker from detection of clots or flakes in the milk, from a cow that has a quarter sensitive to the touch (she kicks a lot when you touch a particular quarter), a quarter that is swollen or hot to the touch. Because the cow's udder then contains antibiotics which must be kept out of the food supply, that cow's milk must not be put into the milk tank for some specified number of milkings after treatment. Typically this milk is either dumped down the drain or used to feed calves. Clear identification of the treated cow is critical to be sure the cow's milk is not inadvertently put into the milk tank. Shipping milk contaminated with antibiotics can lead the producer to lose their permit to ship Grade A milk; that is they are out of business. use of leg-bands or some other physical marker on the cow, as well as clear records of antibiotic administration are essential for this process. It is quite common for a cow to be treated multiple milkings with the antibiotics.

Intramammary infusions: Prior to intramammary infusion, the teat is cleaned well and the tip of the teat is swabbed with an alchohol swab and allowed to dry for a number of seconds. The antibiotic comes in a plastic tube with a plastic infusion cannula on the end. Historically these have been long cannulas and the cannula was inserted completely through the streak canal (called full insertion). However, it was realized that this could be carrying bacteria into the teat cistern. More recently a shorter infusion cannula has been used in what is called a partial insertion method where the cannula only goes about half-way up into the streak canal and the antibiotic is expelled from the tube into the teat cistern. After emptying the antibiotic tube, the teat is pinched off and the antibiotic fluid is palpated up into the gland.

Infusion of antibiotic into a cow's quarter.

Oxytocin treatment: A key contributing factor to duration of mastitis is the frequency and completeness of milk removal from the infected quarter. In some cases, cows are stripped between normal milking times, sometimes with injection of oxytocin to stimulate an effective milk let down. Clearly removal of the primary growth medium of the bacteria, the milk, more often should enhance rate of recovery from infection.

Non-responding cases: Inspite of the natural resistance mechanisms of the cow, antibiotic treatment to help her fight bacterial infection, and other methods such as frequently stripping out the milk, some cows are unable to elimiate the infection. These are often considered to be chronically infected cows, typically with Staph. aureus, and remain a constant source of infection for other cows. Culling of chronically infected cows sometimes is the only way to effectively control spread of mastitis in the herd.


Control of Mastitis

Awareness of the economic losses associated with mastitis is resulting in a desire for mastitis control programs. Control programs are focused on detection of mastitis (by the above methods), identification of the causative agent(s) and prevention of transmission by removing the source of the agent (milk contaminated fomites, bedding, persistently infected cows, etc.). Knowledge of mammary anatomy and physiology, mammary defense mechanism, microbial habitats, microbial virulence factors, milking machine function, and antibiotics/germicides is important in achieving effective mastitis control.


Control of Contagious Mastitis : Contagious mastitis can be effectively controlled through a rigorous program of teat dipping and dry cow antibiotic treatment. Teats must be dipped in germicide after each milking (this decreases incidence of the disease). Each quarter must be treated with dry cow antibiotics at end of lactation (this decreases prevalence of the disease). Cows with contagious mastitis should be milked last or a separate milking claw used for the infected cows. Milking claws should be flushed with hot water or germicide after milking infected cows (called backflushing). Individual cloth/paper towels should be used to wash/dry teats. Milkers should have clean hands and wear latex gloves. New additions to the herd should be cultured and persistently infected cows should be culled. Teat lesions should be minimized (from chapping, frostbite, stepped-on teats, lacerations, or machine damage). Heifers can be given dry cow antibiotic treatment during gestation if S. aureus is a problem in the heifers.

Teat dipping.
Intramammary antibiotic infusion.
Post-milking teat dipping with a germicide Intramammary infusion with dry cow antibiotic therapy at drying off of the cow.
Paper towels in milking parlor.
Milking machine.
Use of individual paper towels to wash and dry teats before milking. Proper milking machine function is necessary for control of contagious mastitis.

Control of Environmental Mastitis : Environmental pathogens are more difficult to control than the contagious pathogens. Many of these organisms are resistant to germicides in teat dip and antibiotics in dry cow therapy. Identification of the source and removal (bedding, ponds, mud) is the key to control. Udders can be clipped to minimize the amount of manure clinging to the glands. Only clean dry teats should be milked. Teats should be pre-dipped with germicide before milking. Cows should be kept standing after milking (offer them feed). Sterile single-dose infusion products should be used and sterile infusion techniques (alcohol swab) should be used. The milking parlor should be kept clean. The teat dipper should be kept clean; organisms an survive in many germicides. Pipelines/water heater may need to be replaced in cases of Pseudomonas contamination.

Dirty udder.
Clipped udder.
Dirty, unclipped udder can contribute to environmental mastitis. Clipped, clean udder.
Bedded stalls.
Cows at bunker.
Bedding of stalls is important to minimizing environmental mastitis. Cows eating at bunker after milking. Keeping cows standing after milking allows time for closure of the streak canal which can stay dilated for over an hour postmilking.

Vaccination for Mastitis

Development of potential vaccines to prevent or control mastitis continues to be an important goal. Excellent progress has been made toward coliform mastitis control with the development of mutant gram negative vaccines. The organisms used (E. coli and Salmonella) have lost the ability to synthesize outer polysaccharide antigens, resulting in exposure of common gram negative LPS (lipo-polysaccharide) antigens. Antibodies produced against these antigens are cross-reactive among gram negative pathogens. When used as directed, there is approximately a 70% decrease in clinical coliform mastitis, as well as a decrease in severity of clinical signs. Cost:benefit ratio is high in problem herds.

Many attempts have been directed toward development of an effective vaccine for Staphylococcus aureus. Vaccines have been created (eg. from Protein A) and injected intramuscularly or into the area of the supramammary lymph node. Vaccination has been unsuccessful in reducing the number of new cases of mastitis. Some vaccines have been effective in improving spontaneous cure rates and reducing severity of infection. These vaccines result in an increase in all types of leukocytes in the gland, thus improving defense. Overall, the success of vaccination has been minimal. Most of these vaccines have used bacteria cultured in-vitro, have been killed vaccines, and have stimulated production of IgG1. Development of a Staph aureus vaccine is an ongoing objective of much research.


Approaches to Mastitis Herd Problems

General considerations:

Confirm that the problem exists - define it

Verbal history from producer
Herd records (DHIA, milk yield, SCC, records of treatment)
Examination of cows (palpate udders, milk SCC, CMT score)
Culture of cows and/or bulk tank

Determine the cause or predisposing factors

Milking procedures - watch them during milking.
Milking machine
Environment


Make appropriate control recommendations

Practical
Economical
Prioritized

Monitor progress

Milk production and quality
Herd records
Follow-up cultures (cow or bulk tank)

Results take time.

Problems Leading to Herd Investigation

  • High somatic cell count
Bulk tank SCC approaches or exceeds Grade A limit (750,000 cells/ml)
Bulk tank SCC limits premium payments
Sudden or gradual increase in SCC
Cows with persistently high SCC


Relationship between SCC, linear score (log of SCC), and milk yield loss. For each 100,000 cell/ml increase in bulk tank, loss of ~.25 liters/cow/day.

  • High incidence of clinical mastitis
Less than 2% of cows/month
45-50 cases/100 cow lactations
$100/case

  • Milk quality problem
Bacteria count, PI count
Mastitis, udder hygiene, milking equipment sanitation, refrigeration

  • Milking machine problem
  • Teat Lesions
From milking machine (teat congestion)
Teat lacerations
Frost bite
Contagious lesions, psuedo-cow pox, Herpes mammillitis

Mastitis Case Studies
Mastitis Resources