Generally, any evidence of change in reproductive performance or of genitourinary disorders detected on physical examination
or laboratory analysis indicates the need for ultrasound evaluation in the male dog and cat. Ultrasonographic examination
of the testes, epididymi and prostate gland can demonstrate lesions too small or inaccessible for detection via palpation,
and permits differentiation of soft tissue details not recognized with radiography. In the tom cat, ultrasound evaluation
of the testes for morphologic abnormalities can assist in the difficult diagnostic evaluation of infertility.
Discussion of some of the controversial and challenging clinical problems in male reproduction familiar to the small animal
practice follows. In each of these cases, ultrasound was essential to the diagnosis.
Ultrasonographic Evaluation of Disorders of the Male Reproductive Tract
Infertility
Evaluation of the infertile (normal libido) stud dog's general and urogenital health by appropriate laboratory analysis of
blood, urine and both the sperm rich and prostatic portions of the ejaculate complements ultrasonography. Testicular ultrasound
should be performed in every patient with unexplained infertility and abnormal sperm analysis. It allows diagnosis of more
pathologic conditions than physical examination. Subtle differences in testicular or epididymal size or symmetry, or changes
in testicular or epididymal consistency warrant an ultrasonographic evaluation which can disclose pathology (i.e. orchitis,
epididymitis, testicular neoplasia) sometimes before reproductive performance has been irreversibly affected. In human ultrasonography,
color Doppler ultrasound allows rapid varicocele screening, not reported in the dog.
The clinical evaluation of infertile tom cats is limited as semen is difficult to obtain without electroejaculation or special
training. Observation of sperm in the urine of the tom, or in the vestibule/vagina of queens recently bred can confirm spermatogenesis.
Ultrasound of the testes can confirm normal morphology, provides an exact measure of testicular volume, and allows the detection
of the presence of dystrophic changes in the testicle, as well as anomalies of the epididymis and vas deferens, such as cystic
dilations.
The prostate should be evaluated ultrasonographically in every stud dog periodically, due to the predisposition for benign
hyperplasia, cystic hyperplasia and potential for prostatitis in intact males. When prostatic disease is suggested by clinical
evaluation (palpation, evaluation of the third fraction of the ejaculate, urinary tract infection) ultrasonographic evaluation
of the prostate gland is indicated.
Prostatic Disease
The use of ultrasound in the evaluation of prostatic disorders permits prompt, accurate assessment of the gland for internal
cavitations and changes in its normal parenchyma, symmetry, position or shape. In combination with cytologic and microbiologic
evaluation of prostatic fluid, this information permits accurate and noninvasive information important to the evaluation of
abnormal preputial discharge, change in the color or volume of ejaculate, and urogenital pain or urinary habits. Ultrasound
guided prostatic aspirate or biopsy has greatly facilitated the differentiation of benign hyperplasia, infection/inflammation,
and neoplasia and is minimally invasive. Ultrasound guided drainage of intraprostatic abscesses may hasten recovery. Sequential
prostatic ultrasonography provides valuable information on the efficacy of therapy.
Mineralization within the prostate will appear as highly echogenic slashes with attenuating shadows. Mineralization can be
seen in both the intact and neutered male prostate. Mineralization in any prostate or prostatic pod is an abnormal finding,
and should help define clinical findings (hematuria, stranguria). Mineralization can be associated with chronic prostatitis
or prostatic neoplasia.
Prostatic hyperplasia causes symmetric, mild enlargement of the gland with mildly increased echogenicity which may progress
to become patchy. The shape of the gland may change from bi-lobed to circular in the transverse plane. Prostatic cysts, being
fluid filled, will be easily seen as hypoechoic structures within the prostate. Many times prostatic cysts will produce an
enhanced (white shadow) artifact. Fluid cavitations are seen with cystic prostatic hyperplasia and are difficult to differentiate
from early abscessation associated with prostatitis, clinical differentiation is indicated.
Mild early septic prostatitis may be difficult to differentiate from benign cystic hyperplasia, clinical testing of urine,
semen and prostatic fluid may be necessary. Chronic, severe prostatis can cause the appearance of poorly marginated multifocal
mixed echogenicity with infrequent mineralization. Sublumbar lymphadenomegaly may be present.
