Inguinal (scrotal) hernias
Keywords: ovine, ram, scrotum herniaThese illustrations are more than 30 years old but still of interest.
Figure 1. A massive unilateral, inguinal hernia in the left side of the scrotum of a ram. Image size: 1000 x 806px
This ram was presented for investigation of long-standing enlargement of its scrotum. Due to the age of the animal and the potential for life-threatening developments, it was euthanized.
Various medical dictionaries define a hernia as "... a bulge or protrusion of an organ through the structure or muscle that usually contains it". This condition therefore, should be referred as an inguinal hernia rather than a scrotal hernia. This is based on the fact that the scrotum itself has not been penetrated. An analogy would be to refer (incorrectly) to a diaphragmatic hernia as a thoracic hernia.
In the case of a direct hernia, the protruding organ exits through a torn muscle layer/s. In direct inguinal (scrotal) hernias, the hernia has no guiding path and therefore, seldom protrudes far into the scrotum. More commonly, inguinal hernias are indirect; described as such because they do not penetrate muscle layers. Instead, viscera enter the internal inguinal opening and occupy the vaginal cavity of the scrotum.
The condition in this ram is correctly be referred to as an indirect inguinal hernia.
In normal males, the testis is covered intimately by the tunica albuginea. In turn, those structures are contained within the visceral vaginal tunic. The visceral vaginal tunic on the left and right of the testis fuses caudal to the testis where the fused portion envelopes the epididymis and ductus deferens. The vaginal tunic then reflects parietally on either side of the testis, forming the vaginal cavity between the parietal and visceral layers of the tunic. The vaginal cavity is continuous with the peritoneal cavity but the vaginal canal is normally narrow enough to prevent viscera from entering the vaginal cavity.
In this ram, the inguinal canal became dilated to the point where intestines escaped into the left vaginal cavity; a classic indirect inguinal hernia. However, this case was remarkable because a large volume of serum and fibrin accumulated around the left testis, between its tunica albuginea and the visceral layer of the left vaginal tunic. Presumably, vascular embarrassment in the left inguinal canal caused plasma to escape from the pampiniform plexus and other vessels around the left testis. This then dissected into the potential space between the tunica albuginea over the left testis and the left visceral vaginal tunic. Eventually, large amounts of fibrin and serum accumulated in this space.
Perhaps obviously, this ram would have been infertile because of a temperature insult to the left testis caused by the presence of intestines, combined with insulation of the testis by the surrounding layer of serum and fibrin. Spermatogenesis may have been been present in the right testis but its smaller-than-normal size suggested otherwise. Certainly, this ram would not be suitable for breeding.
A less dramatic scrotal hernial in a Texel ram is show in figure 2.
Figure 2 A scrotal hernial in a Texel ram. The typical ultrasound findings (showing intestinal loops within the scrotum) is shown within the inset. Image size: 1000 x 1334px
Inguinal hernias in rams are not common and inguinal herniation in rams has received little attention in the literature, especially in contrast to boars, bulls and stallions where the condition is considered heritable. There is however, some suggestion that inguinal hernias are also heritable in rams. In light of these statements it is surprising to find several reports of surgical repair of inguinal hernias in both sheep and goats.
Selected references:
Murray. R. M. 1969. Scrotal abnormalities in rams in tropical Queensland with particular reference to ovine Brucellosis and its control. Australian Vet.J. 45: 63-67
Roberts, S. J. 1988. Scrotal hernia in rams. A case report. Cornell Vet. 78: 351-352.
Roberts, S. J. (ed).1986. Veterinary obstetrics and genital diseases (Theriogenology). Published by author, Woodstock, VT 05091. ISBN-10: 9997670922 ISBN-13: 978-9997670922. pp 822-823.
Scott, P. 2012. Ram breeding soundness - some common scrotal and testicular abnormalities. Livestock. 17: 37-41
