Page 558 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

Reproductive system: 2.2 The male reproductive tr act 533

VetBooks.ir Aetiology/pathophysiology (e.g. providing light and airy housing, encouraging
exercise, providing exposure to mares and elimi-
Lack of libido can be caused by a number of physical
and psychological factors. In novice stallions, sexual
stallions usually benefit from being housed in the
inexperience may result in slow sexual responses. nating exposure to other stallions). Low-libido
Endocrinological and physiological function is usu- mare barn. Testosterone levels, libido and sperm
ally normal. Genetic selection for placid tempera- production may increase significantly when a low-
ment, stressful housing conditions and previous libido stallion is no longer housed exclusively with
punishment for exhibition of sexual arousal all con- other stallions. Teasing and breeding experiences
tribute to low libido in young stallions. In experi- should be positive and pain free. This is achieved
enced stallions a decline in libido can be caused by a through patient handling techniques with mini-
negative sexual experience, overuse, use during the mal restraint, a safe and distraction-free environ-
non-breeding season, management changes, ortho- ment and exposure to mares in the peak of oestrus.
paedic pain or systemic disease. Negative sexual Stallions are brought in hand to the breeding area
experiences include accidents such as kicks or falls, and allowed to tease one or more oestrus mares for
as well as less apparent traumas such as chaffing or 30 minutes once or twice daily. Walking and cir-
burns caused by the artificial vagina or phantom. cling the mare and allowing the stallion to tease face
to face and mount without an erection may improve
Clinical presentation arousal. GnRH (50 μg 1 and 2 hours before breed-
Young stallions exhibit prolonged sniffing, nuzzling, ing) increases testosterone levels and may increase
and Flehmen behaviour and are slow to develop an libido. Table 2.5 gives the indications and dosages
erection and mount. Inexperienced stallions may play for drugs commonly used in stallion reproduction.
and nip the tease mare without achieving an erection. Table 2.6 gives the effects of some medications on
They seem to lack focus and are easily distracted. reproduction in stallions. In older stallions exhib-
Experienced stallions may present with declining iting declining libido, appropriate management
libido manifested as less vigorous teasing behaviour, changes are similar to those for young stallions.
lack of focus and more mounts per ejaculation. Additionally, orthopaedic disease should be treated
appropriately with anti-inflammatories, shoeing or
Differential diagnosis joint injections. The breeding process is modified
Erectile dysfunction; ejaculatory failure. to provide maximum comfort, including ensuring
that the phantom or mare is at an ideal height or
Diagnosis training the stallion to collect from the ground.
The clinician must be familiar with the range of The stallion’s sexual workload should be minimised
normal stallion behaviour. Quiet observation of the by reducing the number of mares bred and ensur-
breeding routine, including preparation of the mare ing mares are bred once at the optimum time dur-
or breeding mount and artificial vagina, stallion han- ing oestrus. A stallion with low libido may only be
dling and washing, and teasing and mounting behav- able to cover three mares per week, compared with
iour, will often reveal the cause of poor libido. For high-libido stallions that may breed three or four
experienced stallions, a detailed history will focus on times per day, 6 days of the week.
recent changes in routine, and physical examination
will focus on the diagnosis of systemic, neurological Prognosis
and orthopaedic disease. The clinician should also The prognosis depends on the root cause of the low
observe the stallion’s housing situation, turnout and libido. In young stallions the prognosis is gener-
exercise routines, as well as nutrition. ally excellent, with most stallions improving sig-
nificantly with patient training. In mature stallions
Management the prognosis for improvement is good; however,
The cornerstones of treatment in young stallions the breeding schedule may need to be permanently
are handler education and improved management reduced.