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Dystocia 279

PHYSICAL EXAM FINDINGS temperature drop occur 12-24 hours before • Previous ultrasound measurements (days
stage I labor begins.
• Physical exam may be unremarkable; normal • Stage II labor begins when abdominal 25-50 of gestation) can be helpful in deter-
VetBooks.ir • Typically, dams in stage I labor (uterine efforts (tenesmus) coincide with myometrial data are not available. Ultrasound evaluation Diseases and Disorders
mining gestational age when ovulation timing
physical exam findings do not rule out
dystocia.
of intestinal motility or renal architecture as
contractions, resulting in the delivery of a
contractions) or stage II labor (uterine and
abdominal contractions) are euthermic, neonate through the birth canal. Strong indicators of term gestation are not accurate
abdominal contractions do not mean myo-
in dogs or cats. Radiography of a pregnant
mildly agitated, trembling, mildly hyper- metrial contractions are present or adequate. bitch at term should show mineralization
pneic, and nesting. Mild hypothermia • Stage III labor consists of the delivery of the of fetal dentition.
associated with luteolysis at term can be placenta. • Completion of labor, client misinformation
prodromal to labor. • Dams typically progress through stage I labor about litter size
• Abnormal physical findings include moder- in 12-24 hours and then alternate between
ate to severe pain, atypical vulvar discharge stages II and III until all fetuses and placentae Initial Database
(green, malodorous, frankly hemorrhagic), are delivered. Placentae normally may be • Minimally, hematocrit and total protein (mild
a fetus or fetal membranes remaining in the delivered with the neonate or separately and decreases expected due to hemodilution),
birth canal (i.e., presence of a fetus caudal often are consumed quickly, making correct blood glucose (decreased with prolonged
to the cervix, which may be palpable over counting difficult. labor), serum electrolytes, and ionized
the brim of the pelvis or may be partially Common causes of dystocia: calcium (hypocalcemia possible with pro-
protruding out of the vulva), muscle tremors, • Maternal dystocia: primary (no myometrial longed labor) should be evaluated. Urine can
tetany, fatigue/weakness, persistent vomiting, contractions occur) or secondary (myometrial be checked for glucose/ketones (indicating
and protracted tenesmus (abdominal efforts). contractions falter) uterine inertia, birth prenatal diabetes or malnourishment).
○ Uteroverdin (green vaginal discharge) indi- canal (strictures) or abdominal wall (hernias) • Vaginal digital and/or vaginoscopic
cates placental separation and underscores defects, severe vulvar edema, lack of lubrica- (p. 1184) exam to determine if a vaginal
the need for veterinary medical or surgical tion in the birth canal, uterine torsion or obstruction exists. In the dog, the cervix
intervention if fetal delivery is not prompt. tear, metabolic derangements (assessing for dilation) and cranial vagina
○ Malodorous discharge suggests fetal death • Fetal dystocia: oversized, malformed (ana- (assessing for obstruction) are beyond the
and necrosis or metritis. sarca), malpositioned, malpostured fetus reach of the human finger.
○ Inappropriately voluminous hemorrhage • Combined maternal/fetal dystocia: mismatch • Abdominal ultrasound or fetal Doppler
should prompt evaluation for uterine or of birth canal size versus fetal size evaluation to assess fetal viability (normal
vaginal trauma (torsion, tear) requiring • Cranial and caudal (breech in humans) fetal heart rate > 200 beats/min; stress causes
surgical exploration or abnormal placental presentations in dogs and cats are normal. fetal bradycardia).
site coagulation (coagulopathy). • Abdominal radiograph to evaluate litter size,
• Protracted muscle tremors, tetany, repeated DIAGNOSIS relative fetal size, appearance, and position.
vomiting, or marked fatigue suggest
metabolic abnormalities (hypoglycemia, Diagnostic Overview Advanced or Confirmatory Testing
hypocalcemia, ketosis) or exhaustion. A correct diagnosis of dystocia depends on • Uterine monitoring (tocodynamometry) to
• Protracted tenesmus suggests an obstruction taking an accurate history and performing assess presence, strength, and frequency of
or uterine inertia. an appropriate physical exam in a timely contractions.
manner. • Canine and feline uterine monitors are
Etiology and Pathophysiology available for short- or long-term lease
Normal labor proceeds through three stages: Differential Diagnosis through Veterinary Perinatal Services
• Stage I labor begins with the progressive • Normal labor; usually stage I (www.whelpwise.com).
increase in the frequency and strength of • Misinformation about gestational length (see • Tocodynamometry is the only method of
myometrial contractions. Typically, luteolysis History, Chief Complaint), in which case, confirming uterine inertia, differentiating
(progesterone < 2 ng/mL) and the associated lack of labor is then normal primary from secondary inertia, or directly
evaluating the quality of uterine contractions
and response to medical therapy.
TREATMENT

Treatment Overview
Therapeutic goals:
• Facilitate delivery of viable neonates, with
minimal morbidity to the dam.
• Avoid unnecessary surgical intervention by
timely diagnosis and medical intervention.
• Differentiate cases requiring surgical versus
medical intervention. Surgery is warranted
if
○ Refractory (unresponsive) uterine inertia
○ Fetal distress and suboptimal response to
medical management
○ Intractable pain in bitch or queen
○ Obvious mismatch of fetal-maternal birth
canal size
○ Birth canal abnormalities, such as stric-
DYSTOCIA Lateral abdominal radiograph shows the skull of term canine fetus. Arrow indicates mineralized tures or pelvic stenosis that cannot be
fetal dentition. remedied

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