Oorsig/Review
Collection of microbiology specimens and
spleen smears
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Thyroid gland examination
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The gland is located on either side of the larynx
linked by a thin isthmus. In general terms if the
gland is easy to locate on gross examination it is
probably enlarged. Weigh the gland and collect
for histopathology. Ensure slice through capsule
for adequate formalin fixation.
Figure 9: Visceral pleural fibrosis.png
interstitial pneumonia is indicative of viral or
toxic causes of abortion.
Calculate the thyroid weight to body weight
ratio.
•
Thyroid weight (in grams) ÷ Body weight
ratio (in grams) – Express as percentage
(target ratio <0.03%).
Figure 10: Miliary hepatic necrosis (IBR abortion)
Enlarged thyroid glands (hyperplastic goiter) in
late stage abortions, stillbirths, perinatal deaths or
weak neonates in cattle, sheep and goats, should
alert the investigator to possible underlying
micronutrient deficiencies / imbalances (iodine,
selenium, copper, manganese, iron, chromium)
especially when accompanied by cardiomyopathy,
ingestion of goitrogenic plants / anti-thyroid
compounds by the dam (in particular prussic
acid containing plants), in-utero exposure to
certain toxic agents (mycotoxins) or ingestion of
endocrine disrupting agents by the dam.
Internal organ examination
Heart: open the pericardium to examine for
evidence of pericarditis, which is an indicator
lesion for bacterial abortion. Observe the
myocardium for any evidence of myocarditis,
myocardial degeneration or mineralization (see
above). Evaluate the ventricular walls for any
evidence of cardiomyopathy.
Lungs: visceral pleural fibrosis is a normal
finding in ruminant fetuses. Lesions of
bronchopneumonia and pleuropneumonia are
indicative of bacterial causes of abortion, while
6
Liver: multifocal hepatic necrosis is an important
fetal lesion indicative of various infectious causes
including viral (bovine herpesvirus, Rift Valley
fever, Wesselsbron), protozoal (toxoplasmosis)
and bacterial (Listeria, Salmonella). IBR virus
(BHV-1) is an important cause of abortion in
cattle. Abortion generally follows the respiratory
form of the disease or use of modified live IBR
vaccine in pregnant previously unvaccinated
animals, although over the past decade an
apparent increase of post-vaccinal abortion
episodes have been reported in well vaccinated
animals given a booster vaccine during
pregnancy. It is important to remember that
BHV-1 infects ovarian tissue, including corpora
lutea inducing necrotizing oophoritis and return
to estrus. The liver also provides a useful organ
for evaluation of circulatory failure in the fetus as
hepatic cyanotic induration is a lesion commonly
associated with fetal heart failure.
Intestine: in the bovine fetus, necrotizing colitis
is a pathognomonic lesion for Listeria abortion.