Urethral hemorrhage in a gelding.

Keywords: hemorrhage, urethra, gelding, blood

A seven year old Icelandic gelding was presented with a history of severe but sporadic hemorrhage from his urethra. An episode of hemorrhage also occurred during examination.

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The owners reported that large volumes of "pure blood" had been discharged from the penis, not associated with urination.  Dried blood was also present on both hind legs, suggesting that more hemorrhage may have occurred than that seen by the owners.

Endoscopic examination revealed the presence of blood in the urethra (subset image 1) close to the ischial arch. Shortly after the first image was obtained, a column of blood was projected toward the endoscope (subset image 2). Advancing in the direction of the bladder, the urethra was flushed with saline and group of varicose veins was seen (subset image 3 on the left side of the image). No points of hemorrhage could be demonstrated on the surface of these veins, therefore it was impossible to state unequivocally that they were the source of hemorrhage. Just caudal to the bladder (subset image 4) pooled blood was seen ventral to the colliculus seminalis.

Hemorrhage can occur from many sources in the proximal genital tract. These include mucosal tears in the urethra, urethritis, inflammation and neoplasia of the accessory glands and so on. Circumstantially however we concluded that fragility of urethral varicose veins was the source of hemorrhage.

It was with some reservation that yunnan baiyao; a chinese herbal remedy was used to treat this horse. The usual dose recommended for exercise induced pulmonary hemorrhage is “one bottle of powder in the morning and one in the evening”. This is clearly unscientific because the powder has more than 20 ingredients and standardization is therefore virtually impossible. Only a single treatment was used.

Recent contact with the owner revealed that sporadic hemorrhagic episodes occur at three to five day intervals but the gelding remains bright, alert and responsive.  The condition may remain untreated. In similar cases in mares where vaginal varicosities have bled intermittently, the author has recommended ligation or cautery of the vessels but surgical intervention is neither safe nor feasible in this case.

Note: Fatal air embolism has recently been linked with urethral endoscopy. The chance for this is thought to be remote. However, because of this possibility, urethral endoscopy should probably be done only if there are strong indications to do so.

The colliculus seminalis and surrounding duct openings

Keywords: colliculus, gelding, anatomy, equine

As stated by Pozor et al, ejaculatory dysfunction is rare in horses but it is a frustration condition to deal with. For that reason it is important to understand the anatomy of areas of the tract that may be affected. The colliculus seminalis is a site for such pathology, Also, one many encounter urethral hemorrhage and neoplasia in the urethra and for those reasons too, the anatomy of the proximal urethra should also be understood.

The horse shoe-shaped structure seen below is the border of the colliculus seminalis in a gelding. It is situated on the dorsal wall of the urethra just caudal (distal) to the bladder. The orifice towards the bottom of the image is the opening to the bladder (b) and the curved slit-like openings (ed) that are contained within the caudal part of the curved ridge are the so-called “ejaculatory ducts”. Later in this entry, the author suggests an alternate name for the ejaculatory ducts.

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The colliculus is often shown upside down in text books. This is because the endoscopes used to capture those images have fiber-optic systems with hand controls (air/flush) on top of the handles. As those endoscopes curve over the ischial arch, structures situated dorsally in the urethra appear at the bottom of the fiber-optic image; a source of some confusion to the uninitiated. Unfortunately authors seldom think to simply invert these images when they are published! Fortunately, with video-endoscopy, an operator can rotate the endoscope and orient structures correctly.

In vintage medical medical terminology the colliculus was referred to as the verummontanum, the Latin term for a mountain ridge. Nowadays, because the term colliculus is used, it is tempting to deduce that the colliculis as a place where semen collects but this is not correct. The term is actually derived from Latin, where “colliculus” is the diminutive form of “collis” or hill.  Those who speak any of the romance languages and who also hold a fascination for etymology (and geography) will know that the name for a hill is variously "colline", "collina", "colina" etc

In the image below from a mature stallion, one can see the anabolic effect of androgens on the development of the colliculus seminalis and various duct openings. From top to bottom in this image, as the endoscope is advanced, the two rows of openings (left and right) of the bulbourethral glands can be seen. More cranially, within the horse-shoe shape of colliculus itself, the ejaculatory ducts are visible, and on the sides of the colliculus, several openings of the prostate glands.

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This image shows a ventral view (a view of the dorsal aspect of the urethra) of these dissected structures in the same stallion:

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In this view, the author has taken the liberty of using the term common ejaculatory ducts instead of ejaculatory ducts because these short ducts contain both the openings of the ducts of the vesicular glands and the ductus deferentia. In this specimen, where the left common ejaculatory duct has been opened, one finds the openings of the ductus deferentia medial to those of the vesicular glands.

With gentle manipulation, a 9mm endoscope can pass through the openings of the vesicular glands.

A fascinating reference from 1884 (The Anatomy of the Horse: A Dissection Guide by Sir John McFadyean) states that the ducts are: …sufficiently large to permit the tip of a little finger being insinuated into them. “Insinuated” in this sense means to maneuver by subtle manipulation. The author doubts that this term will ever become indispensable in the lexicon of a theriogenologist!.

Between the openings of the common ejaculatory ducts one may a small opening may be present on the midline. It was not visible in this specimen. It is a fused remnant of the two tubes of the mullerian system that have been suppressed by anti-mullerian hormone from Sertoli cells in the testicles. Therefore it is akin to the uterus in females. For that reason it is referred to as the uterus masculinus. In some texts however it is referred to as the utriculus masculinus or even the utriculus prostaticus (because it is found adjacent to the prostate gland). The latter term is inaccurate because “utriculus” actually refers to a sac in Latin, while “uterus” obviously refers to the female organ. As reviewed by Pozor et al., the uterus masculinus may become cystic and occlude the common ejaculatory ducts, interfering with ejaculation.

The following image relates the openings of glands within the common ejaculatory duct and the glands themselves. Because the dissected tract has a somewhat homogeneous color, structures have been color coded to make them more visible.

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Reference: 
Pozor, M.A. et al. 2011. Midline cysts of the colliculus seminalis causing ejaculatory problems in stallions. J. Vet Equine Vet. Sci. 31: 722-721