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10 Ultrasound Examination of the Reproductive Tract
Harry Momont1, Mary Keeler2, and Michael Nicholson2
1 Department of Medical Sciences, School of Veterinary Medicine, University of Wisconsin‐Madison, Madison, WI, USA
2 ABS Global, DeForest, WI, USA
Introduction
Diagnostic ultrasound has become the standard for medical imaging of soft tissue. The genital tract is an obvious target for this diagnostic modality and while ultrasound is routinely employed for evaluation of the female genital system its use in male domestic animals remains much less common. In the bull, for example, the routine bull breeding soundness examination (BBSE) as recommended by the Society for Theriogenology does not require ultrasonographic assessment of the genital system [1, 2]. In many cases of infertility in the bull, adequate diagnostic and prognostic information is obtained without the use of ultrasonography. A major advantage of ultrasonography is the ability to localize and objectively assess morphologic changes in tissue.
A thorough history, complete physical examination, and a BBSE should accompany an ultrasound examination of the bull's genital system. We routinely perform ultrasound evaluations for bulls with palpable or visible abnormalities of the genital system; those with pyospermia, hemospermia, azoospermia, or oligospermia; those with low semen volume; and bulls that persistently produce high numbers of morphologically abnormal or immotile sperm. As with any medical technology, the use of ultrasonography for examination of the bull will expand as veterinarians become more familiar with the modality and its applications.
Equipment and General Methodology
A wide variety of ultrasound equipment is available for diagnostic imaging. Most veterinary clinics providing service to cattle owners will already have a portable, real‐time, B‐mode system with a linear intrarectal probe that is used for reproductive examination of cows. All illustrations in this chapter were obtained with this type of system. Typical probe frequencies range from 5 to 7.5 MHz and are more than adequate for imaging the bull's reproductive tract. More detailed images of the epididymis and penile tissues can be obtained using probes with a smaller footprint and higher frequency. Representative images may be captured, labeled, measured, and saved for inclusion in the medical record. These applications are available with most ultrasound systems.
In order to adequately assess a machine that you intend to purchase, it is advisable to use it in an actual clinical setting so you can critically evaluate functionality and image quality under real‐world conditions. Beyond the primary issue of image quality, durability and resistance to damage from dirt and moisture are important considerations when purchasing an ultrasound unit to be used in cattle environments.
Operator safety is always a concern when working with bulls. A chute or stock with a head catch and squeeze option is ideal. For added security, the bull's head can be secured with a halter. Most bulls will tolerate scrotal, perineal, and rectal examinations with little restraint beyond confinement in the chute. If a kick bar is used behind the bull, extreme caution is needed to avoid placing the arms and hands in a dangerous position. For fractious bulls or for examination of the prepuce and penis cranial to the scrotum, we prefer sedation (xylazine 0.01–0.02 mg/kg IV).
While it is beyond the scope of this chapter, a fundamental understanding of ultrasound