Page 495 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

470 CHAPTER 2

VetBooks.ir 2.77 rupturing of the allantochorion at the cervical star,
the mare attempts to push the placenta and foal
through the vagina as one unit. The presentation of
the allantochorion requires immediate intervention
and rupturing, with rapid delivery of the foal. Many
of the delivered foals are subsequently abnormal and
require treatment.

Aetiology/pathophysiology
This uncommon complication of late pregnancy/
parturition is usually secondary to other problems,
particularly of the placenta. It is most commonly
seen in ascending infectious placentitis, where sepa-
ration may initially occur at the cervical star. Mares
with previously diagnosed placentitis should be con-
tinually observed around foaling to detect and treat
this condition should it occur. It is a recorded com-
plication of induction of parturition and is also seen
with late-gestational stress, excessive nutrition or
Fig. 2.77 A type 4 rectal prolapse in a recently fescue toxicosis.
foaled broodmare. The prolapse contained small
intestine and damaged mesentery and was not Clinical presentation
amenable to repair. Signs of an ascending placentitis including a late-ges-
tational vaginal discharge may be noted. Occasional
Prognosis cases exhibit vaginal bleeding for a few days prior to
The prognosis depends on the degree of damage to parturition. At parturition the red, velvety surface
the bladder, the ease of replacement, the need for of the allantochorion is presented at the vulval lips at
surgical repair of the urethral opening and the pri- the start of second-stage labour (‘red bag delivery’)
mary cause of the straining. There is an increased instead of the whitish amniotic sac that normally
incidence of urinary incontinence after bladder ever- covers the fetus. As the allantochorion has not bro-
sion or prolapse. ken, there will be no release of the placental fluids
(‘breaking of waters’).
RECTAL PROLAPSE
Management
Definition/overview The fetus loses its blood supply as soon as the
This problem is associated with conditions that allantochorion separates and therefore this condi-
cause abdominal straining and can include dystocia, tion requires emergency action. The allantocho-
retained placenta and damage to the reproductive rion should be opened quickly either by manual
tract post foaling (Fig. 2.77). (See also p. 863.) tearing or, if it is thickened, with a sharp object,
preferably at the cervical star. The foal should then
PREMATURE PLACENTAL SEPARATION be delivered as soon as possible and resuscitation
performed and oxygen supplied per nasum if avail-
Definition/overview able. These foals constitute a high risk and many
This emergency at parturition occurs when the are premature, dysmature, maladjusted and/or
allantochorion separates from the endometrium septicaemic. Appropriate prophylactic treatment
before the foal breaks through it and enters the pelvic and management should be instigated as soon as
canal – the ‘red bag’ delivery. Instead of the normal possible.