Two-dimensional ultrasound was used in combination with colour-coded and pulsed Doppler sonography to study the blood flow of the testes and prostate gland in a total of 30 male dogs. After detection of the vessels by colour-coded Doppler sonography, the blood flow patterns were determined by pulsed Doppler sonography measuring and describing the systolic and diastolic peak velocity (SPV, DPV), the end-diastolic velocity, the time-averaged maximum velocity (TAMAX), the pulsatility and resistance index, as well as the ratios of the systolic peak velocity and end-diastolic velocity and of the systolic and diastolic peak velocities. The blood flow of the testicular artery was measured within the pampiniform plexus and the marginal location. The prostatic blood supply was measured in the artery of the deferential duct (cranial), the prostatic artery outside (lateral) and within the gland (subcapsular). The physiological testicular flow pattern was monophasic with a high diastolic flow. Testes with neoplastic alterations showed a significant increase of SPV and TAMAX. The epididymal vessels could not be detected. Under physiological conditions the prostatic blood flow pattern was biphasic in the cranial and lateral location and monophasic in the subcapsular location. Benign prostatic hyperplasia was characterized by a significant increase of SPV, DPV and TAMAX. The results of the present investigation demonstrate that the colour-coded and pulsed Doppler sonography give additional valuable information which improves the andrological diagnostics in the dog.

Concentrations of prolactin (PRL), LH, testosterone (T), TSH and thyroxine (T(4)) were determined before and at 20, 120 and 180 min after a single iv injection of thyrotropin-releasing hormone (TRH) in eight Beagles, eight Fox Terriers, six Labrador Retrievers and five Great Danes that were normospermic. Mean basal PRL concentrations were lower in the Fox Terriers compared with the Great Danes (p < 0.05). Mean LH concentrations were higher in the Fox Terriers than in the Beagles, and T was lower in the Fox Terriers at some times but not others (p < 0.05). Thyroid Stimulating Hormone (TSH) concentrations did not differ among breeds, while mean basal T(4) values were lower in Fox Terriers compared with Labrador Retrievers and Great Danes (p < 0.05). Stimulation of T(4) secretion 120 and 180 min after iv TRH injection was most pronounced in the Beagles and less in the Fox Terriers (p < 0.05). The results of the present study indicate that potential breed differences in circulating concentrations of PRL, LH, T, TSH and T(4) in male dogs with apparently normal fertility can be encountered, but further studies are needed to determine whether the observed differences are typical features of these breeds, reflect subsets of dogs within breeds, or are in part because of possible uncontrolled parameters such as sample timing, ambient photoperiod, housing conditions or diet.