Ultrasonography of the teat canal in cows and sheep

When the isolated teat of a cow was examined with an 8-5 MHz linear array t ransducer in a vertical plane, the teat canal appeared as a thin, white lin e, bordered on each side by parallel, thick, grey-black bands. in a horizon tal plane a comparable image was obtained. in a sheep, images of comparable quality were obtained with a 12 MHz transducer. Histological studies of th e tissues whose removal led to the disappearance of this characteristic ult rasonographic appearance showed that it was associated with the stratified keratinised squamous epithelium with distinct papillae. The content of kera tin in the stratum corneum was apparently responsible for the bright zone; the stratum lucidum was not visible, and the surrounding dark, less echoic area was associated with the stratum granulosum. Doppler echography in live animals confirmed this designation. The outer layers of the teat wall were more echogenic.