INTRODUCTION

Black Bengal goats (BB) are known as poor man’s economy in Bangladesh, because of occupying significant position in the predominantly agro based economy of the country. In recent years, goat production ranked second in terms of the total amount of meat and skin production, they have also proved their worth to stand effectively in overall livestock production of the country (^{Awal et al., 2004}). BB goats are very much familiar for their adaptability, prolificacy, delicious meat and skin quality, also recognized as a breed among the domestic species throughout the Bangladesh and they have tremendous demand all over the world due to extra ordinary quality of meat and skin (^{Fakruzzaman et al., 2012}). In different body systems of BB goat urogenital system is important, where urethra and penis act as a common passage for urine and semen. The urethra has two parts, pelvic urethra and penile urethra. The penis has three parts like root, body and glans penis with or without urethral process .The urethral process and sigmoid flexure are present in buck and ram (^{Getty et al., 1975}). This urogenital tract has both anatomical and clinical importance. Urethral process, distal aspect of the sigmoid flexure, urethra at the pelvic arch and neck of urinary bladder in small ruminants are very much prone to occur obstructive urolithiasis (^{Gugjoo et al., 2013}). Obstructive urolithiasis are commonly occurs in buck than doe, due to longer length and narrower diameter of urethral passage in buck than doe (Getty et al.; ^{Van Metre & Smith, 1995}). Obstructive urolithiasis in the urethral passage is a difficult problem; long term success requires in surgical management to relive urethral obstruction in small ruminants (^{Fortier et al., 2004}; Van Metre & Fubini, 2006). For that surgical management, different knowledge like normal anatomy of penis and urethra is important. Presence of castration and age of Castration plays a vital role for the development of urethral passage and occurrence of urolithiasis (^{Ghoshal & Bal, 1976}). Although several works has been reported on the morphology of urogenital tract of the male goat on different breed (Getty et al.; ^{König et al., 2004}; ^{Dyce et al., 2010}) but there is no such type of work on BB goat. Therefore, the present study was carried out to establish baseline work on the normal measurement of the urethral passage and different segments of penis of uncastrated and castrated BB goat which will be supportive for obstructive urolithiasis management.

MATERIAL AND METHOD

This study was conducted on the urogenital tract of 50 BB bucks (25 uncastrated and 25 castrated) at the departments of Anatomy and Histology, faculty of veterinary medicine, Chattogram Veterinary and Animal Sciences University (CVASU), Chattogram, Bangladesh. The goats were adults, apparently healthy and devoid of any external abnormalities and almost same age and weight. The urinary passage (urinary bladder to external urethral orifice) and penis of buck with associated organs were collected from Chattogram City Corporation area. The urogenital tracts were collected scientifically just after skinning of the slaughtered goat without damaging any parts of it. After that, the male urethra and different segments of penis were measured by using metric rules. Mean and variation of the length and diameter of male urethra and different segments of penis (root, body, sigmoid flexure, glans penis and urethral process) in uncastrated and castrated bucks were calculated by using SPSS 11.5 software and necessary photographs were taken for better illustration of methods and result (Fig. 1 to 5).

Fig. 1 Different portion of urethra and penis. 

Fig. 2 Size and location of Urethral Process (UP) and Glans Penis (GP).  

Fig. 3 Root (R), Sigmoid Flexure (S), Body (B), Glans Penis (GP), Urethral Process (UP) of a buck penis. 

Fig. 4 Series of uncastrated and castrated buck penis. 

Fig. 5 Different portion of urethra and penis a close view. 

RESULTS

Table I showed that, the mean length of the pelvic urethra was 5.88 ± 0.111 cm and 4.58 ± 0.15 cm in uncastrated and castrated buck respectively. The length and diameter of neck of Urinary Bladder (UB) (Fig. 1) in uncastrated and castrated buck was 0.688 ± 0.156 cm, 0.38 ± 0.048 cm and 1.94 ± 0.041 cm, 1.44 ± 0.05 cm respectively. The length and diameter of the Root (R) of the penis (Fig. 1) in uncastrated and castrated buck was 5.02 ± 0.09 cm, 4.24 ± 0.10 cm and 3.7 ± 0.049 cm, 3.3 ± 0.144 cm respectively. Similarly, the length and diameter of Body (B) of the penis (Fig. 3) in uncastrated and castrated buck was 23.48 ± 0.37 cm, 22.74 ± 0.43 cm and 2.63 ± 0.066 cm, 1.86 ± 0.08 cm respectively. The length and diameter of Sigmoid Flexure (SF) (Figs. 1, 3 and 5) of penis in uncastrated and castrated buck was 9.2 ± 0.107 cm, 8.18 ± 0.29 cm and 2.77 ± 0.90 cm, 2.18 ± 0.07 cm respectively. The length and diameter of the Glans Penis (GP) (Fig. 2) in uncastrated and castrated buck was 1.92 ± 0.032 cm, 1.44 ± 0.10 cm and 1.81 ± 0.034 cm, 1.4 ± 0.06 cm respectively. The length and diameter of the Urethral Process (UP) (Figs. 1 to 5) were 2.32 ± 0.029 cm, 1.78 ± 0.07 cm and 0.66 ± 0.014 cm, 0.56 ± 0.05 cm in uncastrated and castrated buck respectively. Finally, the total length of penis in uncastrated and castrated buck was 30.42 ± 0.459 cm and 28.42 ± 0.553 cm respectively (Table I).

List of abbreviations. BB-Black Bengal, B-Body, cm- Centimeter, GP-Glans Penis, NB-Neck of Bladder, PU- Pelvic Urethra, R-Root, S-Sigmoid Flexure, UB-Urinary Bladder, UP-Urethral Process.

Table I Length and diameter of the pelvic urethra and different segment of the penis in black Bengal goat (in cm unit). n = 50, mean ± sd. 

DISCUSSION

The mean length of the Pelvic Urethra (PU) (Table I) in uncastrated buck was significantly (p<0.001) higher than the castrated buck, where pelvic urethra is about 5 to 12 cm in bull and is 15 to 20 cm in boar (Getty et al.). The length and diameter of neck of urinary bladder in uncastrated buck was significantly (p<0.001) higher than the castrated buck. The length and diameter of neck of urinary bladder is varia- ble from species to species and which can be a place for storage of calculi. The length and diameter of the root of the penis in castrated buck was significantly (p<0.001) lower than the uncastrated buck. Due to smaller diameter there is a chance of obstruction due to calculi formation in castrated buck. The length and diameter of the body of penis in uncastrated buck was significantly (p<0.001) higher than the castrated buck. Similarly, the mean value for the length and diameter of the Sigmoid flexure of penis in uncastrated buck was significantly higher (p<0.001) than the castrated buck. In bull, there is an S shape curved sigmoid flexure in the penis which is just caudal to the scrotum; which is about 30 cm of the penis folded up when it is fully retracted. In case of boar the sigmoid flexure is prescrotal, where absent in dog, cat and horse (Getty et al.; ^{Ghosh, 2006}) that indicate the sigmoid flexure of penis is common for buck, bull and boar. This sigmoid flexure has surgical importance because the S shaped sigmoid flexure is quite prone to calculi obstruction which is located just behind the testicle (^{Kinsley et al., 2013}). This flexure frustrates all attempts at passing a catheter from the penis to the bladder because of its curvature (^{Ewoldt et al., 2006}). The mean length and diameter of the glans penis in castrated buck was significantly (p<.001) lower than the uncastrated buck. Glans penis is 8 cm in Bull (Getty et al.) which is higher than buck; it may due to species and size variation. The glans penis is very different forms and minimally develops in pigs, substantial in the ruminants but large and mushroom shaped in horse. In case of dog proximal part of glans penis is bulbar and distal part cylindrical but in cat it is pointing caudoventrally (Dyce et al.). In case of length and diameter of urethral process of uncastrated buck was significantly (p<0.001) higher than the castrated buck. In buck at the terminal part of the penis it was found urethra lies in a groove on the ventral surface of corpus cavernosum. The terminal part was projected about 3-4 cm and 2 to 3 cm beyond the glans penis forming a twisted process of urethra; the description was found similarity with some previous description (Getty et al.; König et al.). In buck urethral process of the penis is common site for obstructive urolithiasis (Kinsley et al.; ^{Tobias & van Amstel, 2013}). Young castrated males are susceptible to urinary calculi because castration stopped both testosterone production and growth of urethra (Ghoshal & Bal; ^{Pugh & Baird, 2012}). The tendency of the occurring urolithiasis also related to the anatomy of urinary tract and age of castration (Gugjoo et al.; ^{Cruze, 2014}). The total length of penis is also significantly lower (p<0.001) in castrated buck than the uncastrated one. Generally, in horse the total length of penis is about 50 cm in quiescent state, whereas the length of penis is about 90 cm in bull, 45 to 50 cm in boar and 10 cm in dog (Getty et al.), which indicate length of buck penis was smaller than bull, horse and boar, it might be due to body size and species variation. From the above discussion it can be said that, castration reduce the growth and development of male urethra and penis (Table I) which could be a cause of urolithiasis formation, those thought found the similarity with some of the previous study (Ghoshal & Bal).Therefore it can say that, the mean length and diameter of the penile urethra and different segment of the penis in uncastrated buck was significantly (p<0.001) higher than the castrated buck, which indicate there is more chance of occurring urolithiasis in castrated buck than uncastrated one due to underdeveloped urethra and penis in BB goat.