Mastitis, Somatic Cells and the CMT
Maxine Kinne

Mastitis is an inflammation in the udder and can occur in any lactating animal. Even non-lactating animals can harbor this infection. Goats can have any of a variety of symptoms or none at all. Any abnormality in the milk may signal mastitis: clotted, stringy, bloody, off-color, off-flavor or reduced production. The udder may feel warm, lumpy or cold. The doe may have a temperature or a depressed appetite.

There are many strategies to prevent mastitis in milking and nursing does. Mastitis is often called a management disease because it can be caused or prevented by MAN. Attention to sanitation in the barn and loafing areas is very important in reducing bacteria in the environment. Sanitary milking procedures, including thoroughly washing each half of the udder with an individual towel and drying each half of the udder with individual paper towels, good milking technique, and post-milking teat dipping are all important steps in preventing mastitis. It is also recommended to keep a milking doe on her feet as long as possible after milking to allow the teat dip to dry and the teat orifice to begin closing. Feeding hay after milking keeps them up for a while. Pre-dipping is also a strategy that can be adopted for milkers.

Selection choices can contribute to mastitis though poor udder and/or teat conformation, large teat orifices, and stress resistance. To prevent dry period infections in does with mastitis during the previous lactation, a dry cow mastitis treatment is infused into each half of the udder. This must be done in an extremely sanitary process or additional bacteria can be introduced into the udder. Trauma to the teats should be minimized by aseptic and gentle application techniques of lactating or dry treatments.

Bacteria cause mastitis, and milk is an excellent medium for bacterial growth. White blood cells, also called leucocytes or somatic cells, respond to fight bacterial infection and are found in mastitic milk in great numbers. Laboratory culture of the diseased milk will determine which organism is causing mastitis, however treatment is usually initiated before the culture results become available. Diagnosing mastitis early in the course of the infection is important in being able to initiate treatment and preserve as much of the udder's milk-producing function as possible for the current and succeeding lactations. It is very helpful to refrigerate or freeze a suspect milk sample before beginning treatment. If treatment doesn't work, you will have an original sample for testing.

The California Mastitis Test (CMT) is one an owner can use to test a doe at any time during lactation. Available from all the veterinary supply houses for about $10, the CMT kit contains a milk collection paddle, test solution and instructions for using it on cows. The paddle is divided into four sections because the cow has four separate mammary glands. Goats have two.

After milking a few streams from one gland to remove bacteria in the streak canal, about a teaspoon of milk is collected in one of the paddle's shallow cups. Collect milk from the other half separately to avoid diluting either sample. Purple reagent solution is added to each milk sample in a quantity equal to the amount of milk that was collected. Then the paddle is swirled around to mix the milk and reagent. The mixed liquid may flow fairly freely or form a gel. The degree of gel formation determines the degree of mastitis. The gel actually indicates the quantity of somatic cells (leucocytes) in the udder to fight bacteria.

Test results fall into four categories: negative, trace, weak and distinct. CMT test results for goats are one step beyond the results for cows. Normal goat milk always shows a trace amount of gel formation, but it is no cause for concern. This is because of goats have an apocrine milk secretion mechanism (small amounts of cell contents discharged during milk secretion) which is different than the cow's merocrine system (through the cell wall with no extra-cellular debris). The doe always produces more somatic cells in milk than the cow. The goat's somatic cells are partly leucocytes and partly cytoplasmic particles which can certainly create confusion about milk quality when testing somatic cell counts using cow standards.

The CMT is an excellent test to have on hand to help you determine whether or not your doe has mastitis and how serious it might be. Milking does' udders are checked for normalcy at each milking. Nursing does are rarely checked, so amastitis infections can quicly get out of hand.

Handle the nursing does' udders frequently and you will be better able to notice problems. Do a CMT and freeze a sample to be able to help your veterinarian find a diagnosis if treatment doesn't work. If you have to treat mastitis, adhere to recommended milk and/or meat withholding times for each of the drugs used.


Related Reading

Mastitis in Dairy Goats
California Mastitis Test - Goats


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