Dystocia

From Dog
Amniotic sac present for 2 hours in a dog with dystocia[1]

Dystocia, defined as a difficult, prolonged or intractable delivery, is relatively common in dogs.

The normal length of gestation post-ovulation in a dog is 62 - 64 days. There are three basic stages of parturition:

  • Stage I - cervical dilation, results form increased estrogen and prostaglandins, and decreased progesterone, uterine contractions and the pressure of the fetus at the cervix. Contractions are not visible.
  • Stage II - expulsion of fetuses - duration varies from 6 - 12 hours. Passage of a neonate every 30 - 60 minutes.
  • Stage III - expulsion of placentas - usually passed 5 - 15 minutes after each pup is born

Although the majority of dystocias are due to uterine inertia, obesity[2], fetal deaths, uterine inertia, dog-bitch size mismatch, malpresentation (breech birth) and narrow pelvic cavity, more rare causes can also contribute to this disorder. As well, small and miniature breeds appear predisposed[3].

In healthy dogs, labor is accompanied by sequential changes in blood concentrations of prostaglandin F2alpha, progesterone, estradiol, oxytocin, vasopressin and elevated cortisol levels[4].

Diagnosis of dystocia can be determined by a number of clinical signs, including:

  • Failure to deliver next pup four hours of a prior delivery, with or without contractions
  • Primary commencement of labor without delivery of a pup after one hour
  • Vaginal discharge (blood, green or black discharge) pre-delivery or during delivery, suggesting placental separation and fetal distress
  • Pup visibly lodged in birth canal
  • Non-responsiveness to oxytocin injections

The duration of labor has a direct influence on neonate survival rates[5].

Uterine inertia, thought to be due to low ionized calcium[6] and heightened progesterone levels at full term[4], is usually responsive to medical intervention[7].

The leading consequence of dystocia is neonatal death of pups, uterine rupture[8], recurrent dystocia, puerperal hypocalcemia, vaginal prolapse, uterine prolapse, pyometra, peritonitis and perineal hernia.

Medical management of dystocia has the advantage of aiding completion of the parturition process without surgery or anesthesia. However, improper medical treatment, especially when surgical management is clinically indicated, can result in compromise and even death of the dam and fetuses[9]. As well, some clients request elective cesarean section to maximize puppy survival and this is a common procedure, particularly with dog breeders[10].

Treatment may be remedial with oxtyocin injections given every 2 hours, but caesarian section is normally recommended to save distressed pups[11].

Dogs with severe dystocia or recurrent dystocia are best desexed to minimize future dystocia episodes.

References

  1. Toa Payoh vets
  2. Zoran DL (2010) Obesity in dogs and cats: a metabolic and endocrine disorder. Vet Clin North Am Small Anim Pract 40(2):221-239
  3. Münnich A & Küchenmeister U (2009) Dystocia in numbers - evidence-based parameters for intervention in the dog: causes for dystocia and treatment recommendations. Reprod Domest Anim 44(2):141-147
  4. 4.0 4.1 Bergström A et al (2010) Hormonal concentrations in bitches with primary uterine inertia. Theriogenology 73(8):1068-1075
  5. Traas AM (2008) Surgical management of canine and feline dystocia. Theriogenology 70(3):337-342
  6. Hollinshead FK et al (2010) Calcium, parathyroid hormone, oxytocin and pH profiles in the whelping bitch. Theriogenology 73(9):1276-1283
  7. Davidson AP (2011) Primary uterine inertia in four labrador bitches. J Am Anim Hosp Assoc 47(2):83-88
  8. Humm KR et al (2010) Uterine rupture and septic peritonitis following dystocia and assisted delivery in a Great Dane bitch. J Am Anim Hosp Assoc 46(5):353-357
  9. Pretzer SD (2008) Medical management of canine and feline dystocia. Theriogenology 70(3):332-336
  10. Smith FO (2007) Challenges in small animal parturition--timing elective and emergency cesarian sections. Theriogenology 68(3):348-353
  11. Silva LC et al (2009) Neonatal clinical evaluation, blood gas and radiographic assessment after normal birth, vaginal dystocia or caesarean section in dogs. Reprod Domest Anim 44(1):160-163