Relationship between of Teat Orifice Morphologic Abnormalities and Subclinical Mastitis in Dairy Cattle

Abstract

The teat orifices of subclinical mastitis cases in dairy cattle were morphologically classified into four types: 1) smooth and well closed (type I), 2) smooth and with small ring (type II), 3) smooth and with large ring (type III and 4) hyperkeratotic (type IV), and the relationship between the teat orifice abnormalities and the occurrence of mastitis was investigated. Fourty-nine out of 150 quarters were shown to have subclinical mastitis based upon bacterial and cell counts, and the positivity rates were 8.3%, 23.1%, 34.8% and 40.8% in types I, II, III and IV, respectively. Histopathology revealed hydropic degeneration in the streak canal of all samples, and cutaneous hyperkeratosis reached the streak canal with remarkable epithelial ablation of the rosette in type IV teats. These results suggested a close correlation between teat orifice abnormalities and the occurrence of subclinical mastitis.