B-mode ultrasonography of mammary glands of cows, goats and sheep during alpha- and beta-adrenergic agonist and oxytocin administration.

Teat and gland cistern of the mammary glands of five dairy cows, five goats and five sheep were scanned in a water bath during alpha- and beta-adrenergic agonist and oxytocin administration. A 5 MHz linear array scanner was used to create vertical cut pictures with the scan plane longitudinally through the teat channel. The i.v. injection of the alpha-adrenergic agonist phenylephrine (30 micrograms/kg) induced diminution of the section area through teat and gland cistern by 38 +/- 17% on average within 1 min in all three species. In contrast, the i.v. injection of the beta-adrenergic agonist isoproterenol (1 microgram/kg) did not change the cisternal areas. The i.v. injection of oxytocin (2.0 x 10(-3) i.u./kg) elicited an enlargement of teat and gland cistern area by 48 +/- 12% on average. Ultrasonography proved to be a valuable system for visualizing changes of the cisternal volume. Smooth muscle contractions in response to phenylephrine administration are thought to cause area reduction, whereas an expected smooth muscle relaxation after injection of isoproterenol could not be observed by ultrasonography. Milk ejection as induced by oxytocin administration caused dramatic enlargement of the cistern area in all three species.