LORI.ovine

Scrotal (inguinal) hernias 

Keywords: scrotum, ram, hernia, intestine, infertility

Note: 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.

Note on terminology:  Hernias are named according the location in which they are located (hiatus, umbilical, abdominal, femoral etc) and whether or not the pass through tissue barriers that did not exist previously such as muscle and connective tissue walls (direct) or into cavities that did exist previously, such as the inguinal canal or congenital cavities around the umbilical cord (indirect). The term inguinal hernia is commonly used to in human medicine. This is because inguinal hernias in men or boys are usually found in the inguinal canal. However, inguinal hernias in humans also progress to occupy both the scrotum as well as the inguinal canal, yet they do not assume the name of this new location. This is almost exclusively a tradition in human medicine. It is probably because inguinal hernias are usually noticeable in animals only once they have become scrotal in location. Therefore veterinarians refer to  them as scrotal hernias. To be completely accurate, perhaps one should refer to these as "inguino-scrotal" hernias. We have used the term scrotal hernia in this entry. When the inguinal canal and vaginal cavity serve as the hernial sac (usually containing intestines) the condition is referred to as an indirect scrotal hernia.  In the case of direct scrotal hernias, the hernial sac enters the scrotum but comes to lie outside the vaginal cavity. Direct scrotal hernias are very rare rare in domestic animal. The cases described here are indirect hernias.

Case 1. Scrotal hernia in a mature Texel ram. 

This ram (precise age unknown) was presented for routine breeding soundness evaluation. Due to the presence of the hernia and the possibility of this being a heritable trait, the ram was culled from the flock.

Figure 1. A right-sided scrotal hernia in a mature Texel ram. A, B and C are ultrasounic cross sections of the scrotum at corresponding levels. Intestines are visible in the vaginal cavity at level A while level B shows only fluid and fibrin. The hernia had not yet progressed to level C. Therefore only cross sections of the left and right testes are seen in that ultrasonograph. Image size: 1624 x 1306 px

Case 2. Massive scrotal hernia in a mature ram.

These images (15 years old) show a massive unilateral, intestinal hernia in the scrotum of an infertile Texel ram. Its age and breed were not recorded in the author's image bank.

This condition is easily diagnosed by ultrasonography but that was not used in this case. The ram was euthanized and went directly for a post mortem examination.

Figure 2.  A massive scrotal hernia in a Texel ram where the left vaginal cavity was distended enormously by loops of intestine. Almost undoubtedly, both testes would have experienced an elevated environmental temperature, resulting in suppression of spermatogenesis and infertility. Image size: 1463 x 1179 px

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.

The heritability of scrotal hernias in rams is not well documented; some authors stating that it is heritable, other deferring to uncertainty.  Scrotal herniation is however, a well documented heritable condition in pigs. Therefore it seems advisable not to repair scrotal hernias in rams.  It is also possible however, that scrotal hernias may result from trauma, and especially in group-housed rams.

Selected references

Al-Sobayil F.A.and Ahmed A.F.2007.Surgical treatment for different forms of hernias in sheep and goats J Vet Sci. 8:185-191

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. (ed).1986. Veterinary obstetrics and genital diseases (Theriogenology). Published by author, Woodstock, VT 05091. ISBN-10: 9997670922 ISBN-13: 978-9997670922. pp 822-823.

Roberts, S. J. 1988. Scrotal hernia in rams. A case report. Cornell Vet. 78: 351-352.

Scott P. 2013. Ram breeding soundness – some common scrotal and testicular abnormalities. UK Vet Livestock Vol. 17, No. 4 https://www.magonlinelibrary.com/doi/abs/10.1111/j.2044-3870.2012.00126.x