Contributors: Prof Gary England, Rob Lofstedt, Mushtaq Memon, Michelle Kutzler

 Species: Feline   |   Classification: Diseases

Introduction Pathogenesis Diagnosis Treatment Outcomes Further Reading


  • Inability of the uterus to contract and initiate parturition, or obstruction of the birth canal.
  • Rare in cat.
  • Seen in primiparous queens over 5 years and multiparous queens over 8 years.
  • Cause: uterine torsion, inguinal hernia of pregnant uterus, excess intrapelvic fat, narrow pelvic outlet, congenital defect within birth canal (eg septal defect or stricture), hypocalcemia, hypoglycemia, systemic illness. 
  • Signs: queen at full term but no contractions (primary uterine inertia), or contractions start but then cease (secondary uterine inertia).
  • Diagnosis: history, clinical signs, vaginal digital examination, biochemical analysis (measure serum calcium and glucose concentrations), ultrasonogaphy, radiography, vaginoscopy.
  • Treatment: administration of calcium and oxytocin as needed, Caesarean section.

Presenting Signs

  • Pregnant queen apparently past term but showing no signs of impending parturition:
    • This may be a sign of primary uterine inertia or may be normal late gestation if the estimate of gestational age was incorrect.
  • Milk can be expressed from the mammary gland in some cases:
    • In primiparous queens, it is not uncommon for milk not to  be present at the onset of labor.
  • Normal signs of parturition develop but then cease (secondary uterine inertia).

Age Predisposition

  • Primiparous queens over 5 years.
  • Multiparous queens over 8 years.
  • Young queens mated in 1st estrus (4-5 months old).
  • Any age (obstructive).

Cost Considerations

Special Risks

  • Inaccuracies in calculating gestation period may cause delivery of premature kittens (but this is much less likely than in bitches as copulation tends to be more closely associated with ovulation in the cat).



  • Failure of uterus to enter the first stage of parturition Parturition (primary uterine inertia).
  • Fatigue after prolonged contractions (secondary uterine inertia).

Predisposing Factors


  • Previous pelvic injury.
  • Pelvic neoplasm.
  • Congenital defect within birth canal, eg septal defect or stricture.
  • Obesity Obesity.
  • Age.
  • Maternal debility/systemic illness.


  • Calcium is essential for normal muscle contraction, therefore if hypocalcemia  →  poor muscle contraction.


  • Usually 2-3 days from recognition of fact that the queen is 'overdue' to the decision to perform a Caesarean section.
  • 3-4 hours after the onset of parturition in cases of secondary uterine inertia brought on by obstructive dystocia Dystocia: fetal.


Client History

  • Queen is 'overdue'.
  • Gestation of more than 65 days.
    Gestation length 63-65 days, but variable with normal range 62-67 days. Can also have split births with a gap in parturition of 24-48 hours.
  • Queen has normal signs which then cease.

Diagnostic Investigation


  • Digital palpation: palpation of the birth canal may reveal the cause of an obstructive dystocia.
  • Ultrasonography Ultrasonography: uterus: confirm well-being of the kittens. Fetal heart rates should be >250 beats/minute. Fetal heart rates <200 beats/minute are indicative of fetal stress. Fetal heart rates <150 beats/minute are associated with high neonatal mortality.
  • Vaginoscopy Cystoscopy: transurethral cystoscopy/vaginoscopy: use an otoscope to evaluate inside of vagina for possible causes of obstruction. 
  • Radiography Radiography: abdomen: if the teeth are visible, the pregnancy should be considered mature Uterus: normal pregnancy (near term) - radiography .
  • Uterine displacement or torsion.
  • Pelvic abnormality.
  • Serum biochemistry: for calcium Blood biochemistry: total calcium and glucose levels Blood biochemistry: glucose.
  • Plasma progesterone Progesterone assay: basal plasma progesterone concentrations indicate that parturition is imminent or has been delayed.


Initial Symptomatic Treatment

Obstructive (secondary uterine inertia)

  • If the birth canal is obstructed, if the fetuses are compromised, if the maternal health is compromised, a Caesarean section Cesarean section should be performed.

Non-obstructive (primary uterine inertia)

  • Calcium gluconate Calcium gluconate (5 ml of 10% solution slowly IV). Asculate heart throughout.
  • Oxytocin Oxytocin (3-5 iu SC or IM. Repeat if necessary in 30-45 minutes). May cause premature placental separation associated with uterine friability. If no response after 2nd oxytocin injection, Caesarean section must be performed.

Subsequent Management

Do not breed from queens with previous history of primary uterine inertia.


  • Ovariohysterectomy  Ovariohysterectomy should be considered to prevent breeding in cats with abnormal pelvic canals or those exhibiting primary uterine inertia.


Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Holst B S, Axnér E, Öhlund M et al (2017) Dystocia in the cat evaluated using an insurance database. J Feline Med Surg 19 (1), 42-47 PubMed.
  • Smith F O (2012) Guide to emergency interception during parturition in the dog and cat.Vet Clin North Am Small Anim Pract 42 (3), 489-499 PubMed.
  • Pretzer S D (2008) Medical management of canine and feline dystocia. Theriogenology 70 (3), 332-336 PubMed.
  • Traas A M (2008) Surgical management of canine and feline dystocia. Theriogenology 70 (3), 337-342 PubMed.

Other Sources of Information