Clinical Examination of Farm Animals - CYF MEDICAL DISTRIBUTION

CHAPTER 11
cally. The efferent ducts of the head and the ductus
epididymis of the tail are readily demonstrable as
fluid filled channels which are less echodense than
the surrounding tissues.
Spermatic cords These are readily palpable as they
run dorsally from each testis towards the inguinal
canal. The cords should be approximately equal in
size, consistency and compressibility. The cords may
become thickened, less mobile and painful to the
touch when inflamed. They contain the spermatic
artery, veins (including the pampiniform plexus),
lymphatics, nerves and the vas deferens. The contents
of the cord can be gently compressed, allowing
them to be identified and compared. The vas
deferens is readily identified as it runs dorsally in
the medial part of the spermatic cord. It is approximately
3 mm in diameter and less compressible
than surrounding tissues. In fat animals, deposits of
adipose tissue may surround the lower part of the
cord within the tunica vaginalis. Inguinal hernia is a
rare condition in cattle. If present, a loop of bowel or
mesentery may be palpable and in many cases is
readily pushed back up into the peritoneal cavity.
Penis This runs from the caudal part of the pelvic
urethra to the glans penis, which in its non-erect,
fully retracted state lies within the caudal part of the
prepuce. The pointed anterior tip of the penis can be
palpated through the preputial skin 10 cm or more
caudal to the preputial orifice. The penis is covered
by the thick, smooth and flexible tunica albuginea
which encloses the two main erectile channels – the
corpora cavernosae penis. A smaller erectile channel
– the corpus cavernosum urethrae – surrounds the
urethra . Penile erection is a reflex act which is induced
by neurohormonal stimulation. The arterial
blood supply to the penis is increased whilst venous
drainage is decreased. Relaxation of the retractor
penis muscle allows the sigmoid flexure to straighten
and the penis to be extruded from the prepuce. Occasionally
abnormal vessels or anastomoses between the
arterial and venous circulations prevent penile erection
from occurring. Affected animals are described
as being impotent and unable to serve.
Glans penis This can only be inspected after it is exposed
by passing through the preputial orifice. Abnormalities
such as a persistent frenulum deviating the
penis downwards when erect and spiral deviation of
the penis (‘corkscrew penis’) may be observed at this
stage (Fig. 11.5). In prepubertal calves the glans penis
is adherent to the prepuce and cannot be extruded. A
brief inspection of the glans penis can be carried out
at the time of service or when the bull is sexually
aroused. A more detailed examination requires
either a general anaesthetic or a pudendal nerve
block to allow relaxation of the retractor penis muscle.
Massage of the accessory glands per rectum may
result in penile extrusion, but is unreliable. The glans
Glans penis
Figure 11.5 Spiral deviation of the penis.
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