Page 890 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

Gastrointestinal system: 4.2 The lower gastrointestinal tr act 865

VetBooks.ir Prognosis Differential diagnosis
Perirectal abscesses need to be differentiated from
The prognosis for types 1 and 2 prolapses is good.
It is poor to grave for types 3 and 4 prolapses as they
are usually associated with severe injuries to the vas- the few neoplasms that develop in perirectal tissue.
Extensive perineal melanoma and melanosarcoma
cular supply and mesentery disruption. may produce clinical signs similar to those of a peri-
rectal abscess.
ANORECTAL LYMPHADENOPATHY/
PERIRECTAL ABSCESS Diagnosis
Diagnosis is based on p/r palpation of a firm perianal
Definition/overview mass. Transrectal ultrasonography reveals enlarge-
Anorectal lymphadenopathy/perirectal abscess is an ment of the anorectal lymph nodes or the presence
uncommon condition that affects mostly young horses of a mature abscess. Cytological examination and
and results in extraluminal obstruction of the rectum. bacteriological culture of aspirates collected percu-
Treatment involves the administration of systemic anti- taneously or through the rectal wall confirm sepsis
microbials and anti-inflammatories, prevention of rectal of the anorectal lymph nodes.
impaction and drainage of the abscess when present.
Management
Aetiology/pathophysiology Management of horses with anorectal lymphade-
In most cases the cause is unknown, but anorectal nopathy aims to treat the anorectal lymph node
lymphadenopathy/perirectal abscess may develop fol- infection, decreasing perirectal swelling and pain
lowing rectal or vaginal puncture or trauma or be sec- and preventing rectal obstruction. NSAIDs, a pro-
ondary to gravitation of a gluteal abscess following an longed course of antimicrobials and oral laxatives
intramuscular injection. Streptococcus zooepidemicus and should therefore be administered.
Escherichia coli are most commonly implicated. Perirectal abscesses should be drained based on
Anorectal lymph nodes are located dorsally in their location either rectally or perianally. This
the retroperitoneal tissue surrounding the rectum. procedure is performed under epidural anaesthesia
Sepsis causes these nodes to enlarge, which may with the horse standing. Postoperatively, drained
result in an extraluminal obstruction of the rectum. abscesses are flushed twice daily with antiseptic
Rarely, the infection progresses into the abdominal solution.
cavity and induces a septic peritonitis.
Prognosis
Clinical presentation The prognosis is good to excellent unless there is
Affected horses display signs of mild abdominal extension of the septic process into the abdominal
pain, depression, anorexia, reduced faecal output, cavity.
tenesmus and fever.

DISORDERS OF THE PERITONEUM

HAEMOPERITONEUM Aetiology/pathophysiology
Haemoperitoneum occurs most commonly in
Definition/overview broodmares as a result of ruptured uterine vessels
Blood loss into the abdominal cavity is an uncom- during or after parturition (see p. 464). Rupture
mon but potentially life-threatening problem. It is of ovarian granulosa cell tumours (Fig. 4.183) or
most common in multiparous mares over 11 years ovarian follicular haematomas, uterine leiomyomas
of age. or leiomyosarcomas may also be associated with
haemoperitoneum in mares. Phaeochromocytoma