Page 461 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

436 CHAPTER 2

VetBooks.ir • History of dystocia or premature placental Vaginal examination
Performing a vaginal examination has some risks
separation.
• History of abnormal pregnancies.
does allow information to be gathered on the cer-
• Vaginal discharge in pregnancy. to the mare and the pregnancy (see above) but it
• Excessive abdominal enlargement. vix, vagina and vestibule. The question of whether
• Severe maternal illness including injury, to perform a vaginal examination depends on the
lameness and infections. presenting clinical signs (e.g. vulval discharge).
• Severe maternal malnutrition. Particular attention to hygiene and cleanliness is
• Twin pregnancy. essential when introducing a speculum or perform-
• Excessively prolonged gestation. ing a digital palpation. The degree of cervical soft-
• Maternal transport and stress, especially last ening can be assessed and samples taken for culture
4 weeks of pregnancy. of any abnormal discharge. (Note: It is essential not
• Severe or prolonged abdominal pain. to breach the cervix in a pregnant mare, as this can
• Maternal drug treatments, general anaesthesia result in abortion.)
and/or surgery.
• Induction of parturition. Blood hormonal analysis
Serial blood samples assayed for maternal plasma
A full clinical examination of the mare should progestin levels can detect trends that may be asso-
always be performed to detect any maternal disease ciated with a compromised fetus and circulating
which may develop and impact on fetal viability (e.g. oestrogen levels are an important indicator of fetal
infection, pyrexia, poor nutrition, poor reproduc- viability. Both are routinely measured. Relaxin may
tive anatomy). Laboratory tests (routine blood tests be a more specific and reliable indicator but it is
[complete blood count, biochemistry] and bacterial not available commercially. Trends in the hormone
culture) are useful to help identify problems and levels within serial samples are more helpful than a
guide treatment and response to treatment. It should single assay. Oestrogen levels increase between 190
be remembered that severe fetal compromise (e.g. and 280 days then fall to baseline levels at term.
from placentitis) does not always equate to abnormal Normal levels are >3671 pmol/l (1000 pg/ml); fetal
laboratory results. distress may be indicated if levels are <3671 pmol/l
The need to assess the fetus has led to a variety of (1000 pg/ml). Before 300 days, oestrogen <1836
different techniques that can be used, often in com- pmol/l (500 pg/ml) may be associated with severe
bination, to assess the health and viability of a fetus fetal compromise/dead fetus. Changes in oestrogen
and reproductive tract. levels do not always occur with fetal compromise. An
increase in progestagens prior to 310 days is strongly
Rectal palpation associated with placental pathology, but it is impor-
This is a simple technique that can assess fetal tant to remember that levels increase in the normal
activity, position and placental fluids. Fetal move- mare as parturition approaches.
ment reflects central nervous system function and
levels of complexity increase during gestation. Fetal and placental ultrasonography
Periods of quiescence can last up to 60 minutes and This can be performed easily on the stud farm and
re-examinations or prolonged examinations may as such, routine monitoring of the high-risk mare
be necessary to assess activity. An absence of move- can be performed in a stress-free environment. The
ment should not be overinterpreted and the mare transrectal approach is ideal for fetal assessment up
should be re-examined on a daily basis. Prolonged to 3 months and for assessment of the uteroplacental
and regular periods of inactivity are associated unit in later gestation. The transabdominal approach
with a negative outcome (likely hypoxia). Fetal requires preparation of the ventral abdomen (hair
activity is reduced if the mare is sedated for the clipping, skin cleansing) and is useful from 3 months
examination. of gestation through to term.