34 - Bovine Mastitis

Abstract

Bovine mastitis is the most costly disease confronting the dairy industry. The disease is manifested as an inflammation of the udder, usually as a result of microbial infection. Mastitis or intramammary infection is generally characterized as clinical and subclinical. Clinical mastitis, sometimes termed “subacute clinical mastitis,” is characterized by an abnormal secretion containing clots or flakes. Sudden onset of clinical mastitis accompanied by swelling, hardness, and increased temperature characterize acute clinical mastitis. Systemic signs such as loss of appetite, fever, dehydration, and depression are also associated with the acute or more fulminate peracute form. No apparent changes in the udder or milk are typical with subclinical mastitis, although microorganisms are isolated by appropriate culture techniques. Compostitional changes and increased somatic cell counts usually accompany subclinical mastitis and are detected by appropriate tests. Chronic mastitis persists throughout lactation and alternates between clinical and subclinical phases. Diagnosis of mastitis is usually based upon isolation of a microorganism coupled with evidence of a host response such as increased milk leukocyte or somatic cell counts. In the cases of clinical mastitis, recovery of microorganisms is sufficient for diagnosis. Diagnosis of subclinical mastitis requires isolation of the causative organism in the presence of elevated somatic cell counts.