Application of B-mode ultrasonography in the assessment of the dog penis

With the purpose to characterize the ultrasonographic features of the dog penis, 20 healthy dogs aged from 2 to 11 years old were used. Ultrasonography was performed using a 5-9MHz linear probe and a Philips HD3 scanner. Ultrasonograms were obtained at the penile body (pre- and post-scrotal sections) and at both the bulbus glandis and the pars longa glandis, with the dog placed in dorsal recumbency. The typical anatomy of the dog penis is easily demonstrated in ultrasonographic images, as revealed in this study. On ultrasonograms taken at the body level, the two corpora cavernosa showed a homogeneous, hypoechoic structure; ventrally, the corpus spongiosum appears as a slightly hyperechoic structure surrounding the urethra. In glans ultrasonograms, the most typical feature is the os penis, observed as a strong hyperechoic structure, whose acoustic shadow impairs the screening of adjacent tissues. Lining on its concavity, the corpus spongiosum is observed as a slightly hyperechoic tissue around the urethra. An ovoid, regularly hypoechoic tissue corresponding to the erectile tissue of the pars longa, surrounds these structures. The bulbus glandis is visualized as a regular hypoechoic structure with small anechoic areas, corresponding to sinusoidal spaces. The albuginea is evidenced as a well-defined, hyperechoic external layer. The preputial cavity appears as a thin anechoic layer surrounding the albuginea. The results of this study demonstrate that ultrasonographic assessment of the dog penis is easily performed and accurate enough for penile examination. Furthermore, ultrasonography of the dog penis can become an interesting diagnostic tool to explore in the canine practice, during breeding soundness evaluation and also whenever penile exposition is impossible to achieve.