Dystocia - Dog & Cat

Introduction

Dystocia is the inability to expel fetuses through the birth canal during parturition.

Signalment

Certain breeds are predisposed to dystocia such as brachycephalic and certain terrier breeds of dog. These breeds have both a narrow pelvis and offspring with large skulls, making dystocia far more common. Many Bulldog breeders now request an elective Caesarean section - however this raises complex ethical issues and it is up to the individual veterinarian to decide whether they are willing to perform the procedure. Siamese and Persian breeds are more likely to suffer from dystocia than other breeds of cat.

Causes

Dystocia can be caused by either primary or secondary uterine inertia.

Primary Uterine Inertia

Primary uterine inertia is defined as a lack of sufficient uterine contractions to expel a normal fetus from a normal birth canal

Secondary Uterine Inertia

Secondary uterine inertia is defined as a lack of sufficient contractions because of either exhaustion from prolonged labor or metabolic disturbances.

Causes:

• Maternal Factors: vulvar or pelvic obstruction; uterine torsion/rupture; hypocalcemia and hypoglycemia
• Fetal factors: fetal oversize - common in small litters and brachycephalic breeds; fetal malpositioning; congenital disorders - fetal monster and hydrocephalus; and fetal mortality.

Clinical Signs

The following signs are suggestive of dystocia:

• If the duration of gestation is >70 days and there is no evidence of the first stages of labour
• Green vaginal discharge is seen without the delivery of a foetus
• A foetus has yet to be expelled more than two hours after foetal fluids are released
• If more than three to four hours have passed since the birth of the last foetus
• If the bitch shows signs of extreme discomfort, systemic illness or exhaustion
• If a foetus is not delivered after 20 - 30 minutes of strong and regular contractions
• The bitches body temperature has dropped below 37.7°C and then returned to normal without evidence of the first stages of labour
• If a specific problem is found on physical exam such as a foetus stuck in the birth canal

Clinical approach to dystocia in small animals

A thorough history regarding breeding dates and previous whelping history is desirable.

Physical examination should look for signs of systemic illness that, if present, may necessitate immediate cesarean section. The normal vaginal discharge at parturition is a dark green colour; abnormal colour or character warrants immediate attention. A dark green/black vaginal discharge associated with a lack of signs of parturition may indicate premature placental separation.

A digital vaginal examination should be performed to evaluate patency of the birth canal and the position and presentation of the fetus(es). Radiography or ultrasonography can determine the presence and number of fetuses, as well as their size, position, and viability.

Manipulation can be attempted in the case of reducible malpresentations or a dead foetus. This involves using digital manipulation sometimes combined with transabdominal manipulation to stabilise the foetus.

Medical management may be considered when the condition of the dam and fetuses is stable, when there is proper fetal position and presentation, and when there is no obstruction. Oxytocin given IM up to 3 times at 30-min intervals, with or without 10% calcium gluconate given slowly IV in an attempt to promote uterine contractions. If no response follows, a cesarean section should be performed.

Caesarean section is indicated for obstructive dystocia, dystocia accompanied by shock or systemic illness, primary uterine inertia, prolonged active labor if medical management has failed. Cases with foetal oversize, foetal malformation, non-reducible malpresentation, foetal distress, and uterine damage should also be managed surgically. should be administered throughout surgery and low doses or short acting, reversible drugs should be used in combination with local anaesthetics to minimise the effects on the fetuses. Recommendations are an opiod for sedation (if required), propofol for induction and isofluorane for maintenance of anaesthesia.

Neonatal Care

Dystocia cases run a higher risk of fetal distress and mortality, therefore it is essential to be prepared for the immediate care of neonates after birth.

Once a foetus has been expelled/removed from the uterus by C-section, the following steps should be performed:

• Removal of the amniotic sac
• Clamp, ligate and disinfect the umbilical cord if the dam is unable to tend to the puppies/kittens herself
• Rub the neonate with a clean towel to dry it and stimulate respiration
• Clear any fluid from the mouth and nose using suction
• Provide oxygen supplementation if the neonate is slow to start breathing

If the neonate does not start breathing spontaneously the following options should be considered:

• Positive pressure ventilation using a mask
• Intubation with an ET-tube or catheter

If opiods have been administered in the dam then Naloxone can be given to the neonate to reverse the effects of the drug.

The puppies should be kept warm and dry (normally by placing them in a box with towel-covered hot water bottles or heatpads) until the dam had recovered. With dogs, the dam should be observed closely when first placed with her offspring as bitches have be known to cannibalise their young. They should be discharged from the hospital promptly to prevent stress and disease exposure.

Dystocia - Dog & Cat Learning Resources
Flashcards Test your knowledge using flashcard type questions	Small Animal Soft Tissue Surgery Q&A 12

References

Gilson, SD (1998) Self-Assessment Colour Review Small Animal Soft Tissue Surgery Manson

Kahn, C. (2005) The Merck Veterinary Manual 9th Edition Merck and Co

von Heimendahl, A. Cariou, M. (2009) Normal parturition and management of dystocia in dogs and cats In Practice 31:254-261