Oorsig/Review
to placental efficiency and fetal growth and
should weigh between 4 to 8 kg and be ±14%
of the fetus/stillbirth weight. Cotyledon
number varies between 75 to 120, with the
average cotyledon diameter of 4 cm when
fully developed at ± 175 days. Reduced
cotyledon numbers are associated with
placental insufficiency in the bovine (figure
4).
Figure 7 - cut surface cotyledon, acute infarcts.jpg
Figure 5 – complete ovine placenta
Examine cotyledons for evidence of adherent
caruncule
tissue,
hemorrhage,
necrosis,
infarction and suppuration (figure 6). To evaluate
for infarcts section through cotyledons to expose
cut surfaces. Presence of infarcts may suggest
mycotic infection or vasculitis (figure 7).
Examine inter-cotyledonary areas for thickening,
Placental weight and cotyledon numbers (80-
100) in small ruminants on the other hand,
are poorly related to fetal growth, with blotted
cotyledon weight being a more reliable indicator
of placental development and efficiency plus fetal
growth. Cotyledons reach their maximum size at
around 90 days of gestation. Total cotyledonary
weight varies from 115-130g with an average
single cotyledon weight of 1.6-1.8g (figure 5).
If available, the entire placenta should be
examined because lesions of placentitis may be
regional. In the normal fresh placenta cotyledons
are red while the inter-cotyledonary areas have
a clear translucent appearance. However, beware
of the effects of post mortal autolysis where
the cotyledons become dull brown and the
intercotyledonary zones less translucent.
Figure 8 - thick leathery exudate in the intercotyledonary area
(Coxiella burnetti)
increased opacity, surface exudate, proliferation
and necrosis (figure 8).
Examine umbilical cord for evidence of torsion.
To qualify as an ante-mortal event congestion,
hemorrhage and edema should accompany the
twists (figure 9).
The following major causes of abortion in
ruminants, frequently only produce placental
pathology with no foetal lesions. So, if only the
foetus is submitted there is an increased risk they
may be missed
Figure 6 - toxoplasmosis with cotyledonary necrosis
6
•
•
•
•
Brucellosis
Coxiella burnetti (Q-Fever)
Chlamydia abortus / pecorum
Toxoplasmosis