Mastitis Can Take On Several Different Forms
From the NMC Newsletter "Udder Topics", August 1996
Udder or intramammary infection is the presence of microorganisms that
multiply in the udder. Infections may be clinical or subclinical, depending
on the degree of inflammation. At times, there is some confusion during
discussions about mastitis because different meanings are applied to the
same term. Therefore, the following definitions are presented.
Subclinical mastitis is a form of the disease in which there
is no detectable change in the udder and no observable abnormalities in
milk. However, the presence of microorganisms in milk usually can be demonstrated
by microbiological culture, and inflammatory changes in the milk can be
detected by special tests, such as conducting a somatic cell count.
Subacute clinical mastitis is a condition in which abnormalities
of the udder and secretion are readily observable. This form of mastitis
can vary in severity, depending in part, on the microorganism causing the
infection. Changes in the milk, such as flakes, clots, and a watery appearance
are the most obvious abnormalities. Heat, swelling, and udder sensitivity
are slight or absent.
Acute mastitis is a condition characterized by sudden onset,
redness, swelling, hardness, pain, grossly abnormal milk, and reduced milk
yield. Systemic symptoms may also be present and include fever, loss of
appetite, reduced rumen function, rapid pulse, dehydration, weakness, and
depression. When the disease onset is very rapid and the signs are very
severe, the disease is termed peracute mastitis.
Chronic mastitis is an udder infection that is of long duration.
Chronic mastitis may remain in a subclinical phase indefinitely, or the
infection may alternate between subclinical and clinical phases; at times,
clinical signs may persist for long periods.
Nonbacterial mastitis is a mammary inflammation that occurs
when microorganisms cannot be isolated from milk samples. Such cases may
be either clinical or subclinical.
Source: NMC Publication "Current Concepts of Bovine Mastitis" (1996)
pg. 1
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