Page 544 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

Reproductive system: 2.2 The male reproductive tr act 519

VetBooks.ir the ejaculate. Season influences the output of the likely function is to cleanse the urethra before
ejaculation. Ultrasonographically, the bulboure-
vesicular glands, with gel fraction volume being
highest during the physiological breeding season.
small hypoechogenic spaces throughout the paren-
Individual stallions may produce larger amounts thral glands appear as oval structures with multiple
of gel fraction than others. Ultrasonographically, chyma. A thin hyperechogenic line representing
the vesicular glands appear in longitudinal section the gland wall is surrounded by the hypoechogenic
as flattened oval to triangular sacs, depending on bulboglandularis muscle, which surrounds the gland
the degree of sexual activity and time since the last (Fig. 2.129).
ejaculation (Fig. 2.128). The size and echogenicity
of fluid within the glands is extremely variable both Ampullary glands
within and between stallions. A thin echogenic wall The ampullary glands are the enlarged distal por-
surrounds a fairly uniformly anechogenic lumen. tions of the deferent ducts. Palpable along the mid-
Increased echogenicity of vesicular gland fluid is line of the pelvic floor over the neck of the bladder,
associated with the highly viscous gel fraction pro- they converge caudally, passing beneath the prostate
duced by some stallions. gland, but lie dorsal to the pelvic urethra. At their
distal ends they continue through the wall of the
Bulbourethral glands urethra, opening into the colliculus seminalis along-
The bulbourethral glands attach to the dorsal sur- side the excretory ducts of the seminal vesicles.
face of the pelvic urethra, about 8 cm caudal to the Each ampulla is identified ultrasonographically
prostate gland. They are not usually palpable per by the hypoechogenic central lumen surrounded by
rectum because they are embedded in the urethra- a uniformly echogenic wall and a hyperechogenic
lis and bulboglandularis muscles. Similar to the outer muscular layer (Fig. 2.130). Hypoechogenic
prostate gland, multiple ductules from the bulbo- areas may be seen within the walls and probably
urethral glands enter the medial aspect of the ure- represent the glandular areas. In many stallions, the
thra, distal to the prostatic ductules. Bulbourethral uterus masculinus, a remnant of the müllerian duct
gland secretions make up the majority of the pre- system, is visible ultrasonographically as one or two
sperm or first fraction of the ejaculate and their cystic structures located between the ampullae.

BREEDING SOUNDNESS EXAMINATION OF THE STALLION

HANDLING A STALLION stallions. Similarly, the stallion must not be allowed
FOR EXAMINATION to rush to the mare or phantom, as this habit becomes
difficult to break. A good fitting, preferably leather
A confident, experienced horse person should handle halter is essential. A long leather lead rope, prefer-
stallions for examination and breeding or semen ably with a good quality chain and clasp, is used to
collection. The handler should be aware of normal provide additional control. Depending on the stal-
stallion breeding behaviour, including vocalisation, lion’s experience and behaviour, the chain can be
prancing and arching of the neck, and not attempt placed over the nose and through the halter rings, or
to discourage or correct these. The handler should through the mouth. Once the handler is comfortable
work with the stallion away from the breeding area with the stallion, the person conducting the exami-
first in order to become familiar with the stallion’s nation can approach. Palpation of the external geni-
behaviour and establish respect. The stallion should talia is probably best performed following semen
respond to both voice and lead corrections and halt, collection when the stallion is more relaxed, willing
back up and turn when asked. Excessive correc- to stand quietly and more likely to tolerate the exam-
tions, beatings or discipline must be avoided as they ination. The handler should always stand on the
can establish long-term behavioural difficulties in same side as the examiner, and clear communication