Page 589 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

564 CHAPTER 2

VetBooks.ir to the accumulation of masses of degenerating sperm prior to massage and collection may assist with reso-
lution of the condition.
and gel in the ampullary glands.
Clinical presentation Prognosis
Complete, bilateral ampullary obstruction presents The prognosis is excellent with appropriate manage-
as azoospermia or, in the case of a stallion breed- ment. The condition is usually reversible and stal-
ing naturally, as infertility. Incomplete obstruction lions return to previous levels of fertility.
presents with semen of very low to zero motility, but
high numbers of sperm. Morphological examina- ACCESSORY GENITAL
tion of sperm often reveals a large number of tailless GLAND INFECTIONS
heads.
Definition/overview
Differential diagnosis The most common accessory genital gland infec-
Incomplete or failed ejaculation; azoospermia of tion encountered is seminal vesiculitis. Rare cases of
other causes; TD as a cause of poor sperm mor- prostate infection/abscess have been reported.
phology; poor semen handling as a cause of sperm
immotility. Aetiology/pathophysiology
The most common causative agents include
Diagnosis Pseudomonas aeruginosa, Klebsiella pneumoniae,
Diagnosis is based on the clinical presentation and Streptococcus spp. and Staphylococcus spp. Infection
a thorough reproductive evaluation. Rectal exami- may occur due to blood-borne infection, ascending
nation and ultrasonography demonstrate unilat- infection or extension of orchitis/epididymitis, or
eral or bilateral enlargement and distension of the secondary to urethritis or cystitis.
ampullae. Measurement of AP activity in the ejacu-
lated semen differentiates between true azoosper- Clinical presentation
mia and obstruction. AP is produced in several The most common clinical presentation is the find-
locations within the male reproductive tract, with ing of polymorphonuclear (PMN) cells and bacteria
the highest production in the tail of the eipididymis in the semen. There may be a concurrent history of
and testicle. Therefore, evaluation of AP levels of recent decline in fertility. Infection may or may not
the semen of a stallion with no sperm will differ- be accompanied by gross changes of colour within
entiate between azoospermia and failed ejaculation. the ejaculate. In acute infections, the stallion may
The normal AP level in pre-ejaculatory fluid is present with painful ejaculation or a reluctance to
10–90 IU/l. AP levels in ejaculatory fluid should be breed, depression and inappetence. Other systemic
in the range of 1,600–50,000 IU/l. A stallion with signs are uncommon and pyrexia is not a typical
apparent azoospermia and AP levels in the pre- finding of accessory gland infection.
ejaculatory range has failed to ejaculate. A stallion
with apparent azoospermia and AP levels in the Differential diagnosis
ejaculatory range can be considered truly azoosper- Culture of bacteria from the semen alone does not
mic. Stallions with bilateral ampullary obstruction confirm vesiculitis, as surface colonisation of the
will have AP levels consistent with the pre-ejacula- penis is the most common source of bacteria cul-
tory fluid range. tured in semen. Other conditions causing PMN cells
in the semen should be considered (e.g. orchitis/epi-
Management didymitis, cystitis or urethritis).
Treatment involves gentle per rectum massage of the
ampullary glands and frequent semen collection in Diagnosis
a short period of time to remove the accumulated The findings of bacteria and PMN cells in the ejac-
sperm. Injection of low doses of oxytocin (10–20 IU) ulate of a stallion should alert the clinician to the