Mastitis

Mastitis can cause 3 different syndromes or groups of disease.

Subclinical

This will cause inflammation in the udder as a result of infection, but not the obvious signs of swelling and hardness associated with clinical mastitis. The only indication of a problem may be raised SCC. This can be picked up on a bulk milk sample if the problem is widespread within the herd, and this should prompt further investigation, or on individual cow and quarter sampling at milk recording or DIY with electrical conductivity, or easier and readily available, a California Milk Test.
Milk recording is a simple and effective way of routinely identifying these risk animals.
Once identified treatment or culling may be required.

Clinical

With clinical mastitis as the name suggests you should see signs of disease such as a hard swollen quarter, clots in the milk or otherwise altered milk secretion. The cow may have a temperature and be off food.
Antibiotic therapy is required.

Acute/peracute

With this syndrome you may have a very sick cow, she may be down with either a very high temperature or latterly a low temperature. She may be anorexic and could die. The clinical signs in the case of acute mastitis are generally caused by the toxins from the infecting bacteria.
Swift treatment is essential.

The cost of mastitis

Mastitis is estimated at costing the UK dairy industry £40 million.

Individually this is a result of a number of factors even before you think about the cost of treatments! (estimates based on 100 cows, annual yield 65000litre at milk price 23p/litre)
o Mortality, 0.6% of clinical mastitis cases will die.
o Premature culling, 3% of mastitis cases are culled earlier than they would be if hadn't been part of the clinical picture. £3600
o Reduced milk production, a decrease of 10-26% of production can be expected from an infected quarter.
o Milk loss, at least 5d of discarded milk from treated cases and 5.9-11% production reduction over the course of the lactation. £149.5/case /year
o High cell counts undetected, 1p loss per litre for scc over 200 000. £1600/year

Contagious Mastitis

The bacteria responsible for causing contagious mastitis are normally found on the teats and udder skin and sometimes in the teat canal. So the reservoir of infection is the animal!

Infection occurs most commonly at milking time, when the udder and teats are being handled. Contact with infected skin with milkers hands, teat liners and contaminated cloth can facilitate passing of the organism from an infected animal to an uninfected one.

Examples of contagious organisms are:
Staph.aureus
Strep. agalactia
Strep. disgalactia

These will usually cause a subclinical mastitis resulting in increase Somatic Cell Counts but not always clinical disease.

Help to reduce the spread of these organisms by:
o Good hygienic milking practice, wear gloves and disinfect clusters after infected animal has been milked
o Clean maintained milking machine
o Post milking teat dip

Teat disinfection and dry cow antibiotic therapy will almost eradicate strep. agalactia. Where as chronically infected staph aureus animals are very difficult to clear particularly if the are past their 3rd lactation cure rate can be as little as 25%. In this type of infection control is based on identifying and removing these animals.

Environmental mastitis

The bacteria responsible for causing environmental mastitis are normally found in soiled bedding/ cows lying out in the passageway/ cubicles of suboptimal size.

Infection from these organisms occurs by teat contamination between milking times and during udder preparation.

Examples of environmental organisms are:
E. coli (faecal contamination)
Strep. uberus (straw bedding especially dry cows and around calving)
Klebsiella (Saw dust and shavings)
Bacillus

These will normally cause a clinical mastitis with obvious changes in the udder and milk. But can on occasion cause subclinical mastitis with raised SCC as the only physical sign of disease

Help to reduce infection by:
o Encouraging cows to remain standing for at least 30min after milking this allows the teat canal to close.
o Adequate, clean accommodation for cows, 5-10% more cubicles and cows, 6m² straw bedding lying space per Holstein cow.
o Pre milking teat disinfection.

Sterile milk sampling

A milk sample that has a bacterial growth is only significant if the sample has been taken in a sterile fashion and has not been contaminated.

1, Thoroughly clean and disinfect the teats starting with the teats furthest away from you and finishing with the closest.
2, Dry the teats in the same order.
With an alcohol swab or wipe disinfect the teat ends again in the same order farthest to nearest.
3, With a clean pare of disposable gloves on, discard 3 fore milk strips, then open the milk pot and, holding at a 45º angle under the teat fill the pot with milk. Sample the teats in the reverse order starting with the nearest and ending with the furthest from you.
4, Clearly label the pot with cow number and quarter with a permanent water proof marker.
5, Either preserve your sample in the freezer or submit to your vet straight away.

Ideally every mastitic cow should be sampled. It must be done where repeat cases or a number in a short time are recorded.

California milk testing

1, and 2, repeat as above.
3, With a clean pair of disposable gloves on, discard 3 fore milk strips, then draw about 3ml of milk from each quarter into the corresponding well on the CMT paddle. Start with the teats closest to you and finish with the ones farthest from you.
4, tip the paddle to discard a small amount of the milk, this will ensure the same volume is in each well.
5, measure about 3ml of CMT detergent into each of the 4 well, swirl and observe.

Thick jelly like agglutination indicates significantly increased SCC in the sample.

How we can help

Different bacteria respond differently to treatment and can carry different consequences. An accurate result from a correctly sampled cow can prove the difference between success and failure.

More information allows more targeted treatment, and hopefully better results for you and your cows.

Please feel free to seek advice from any of our large animal team!