Oxytocin-A Necessary Evil?

submitted with permission by Marj Brooks
with thanks to Kevin & Donna Frizzell of DeSaix St. Bernards for generously allowing us to use many of their superb array of articles

Syntocinon (Oxytocin ~ Pit Shot ~ P.O.P.) or as its more commonly referred to, a “clear out shot” is a synthetic nonapeptide identical with Oxytocin, a hormone released from the posterior lobe of the Pituitary Gland. Synthetic Oxytocin is in a clear sterile aqueous solution. As it is a polypeptide its is largely inactivated in the alimentary tract and therefore virtually ineffective when ingested.

Its principle mechanisms of action are to stimulate the smooth muscle of the uterus producing rhythmic contractions and due to its action on mammary tissue facilitates lactation. It also assists in the involution of the uterus and reduction in uterine bleeding due to subsequent involution after administration.

Usual dosage in large canines is 5 -10iu by subcutaneous injection. Its duration of action is approximately 15 minutes.

Over dosage or Inappropriate Use can result in:

  • Placenta Abrupto: Premature separation of the placenta from the uterine wall
  • Foetal Distress: Resulting in foetal death in utero
  • Uterine Hypertonicity – Tetanic Contraction – Uterine Rupture
  • Amniotic Fluid Embolism
  • Water Intoxication

Whilst all of the above sounds nice and clinical and user friendly Oxytocin is far too underestimated a drug to make random administration safe for the bitch and the puppies that she carries. The reason this drug warrants so much attention is (although it can be a useful clinical tool in the management of certain whelping problems) it is administered far too readily without a full understanding of its implications and contra-indications for use. Oxytocin causes extremely forceful and painful contractions, there is no doubt that they are painful if you watch your bitch after it has been administered and as anyone, who has had a pregnancy induced with Oxytocin will be able to testify and if used recklessly endangers both the life of the dam and the puppies she is carrying.

NEVER ADMINISTER OXYTOCIN IF:

  • The bitch is in labour but has not produced any puppies: this inevitably means that the cervix is either still closed or has not dilated fully or there is a puppy blocking the vaginal canal. Administration of Oxytocin at this time could result in rupture of the uterus, the cervix and even death of the dam.
  • The bitch is contracting and has been straining hard for a while and no puppy has been produced: this inevitably means that there is a birth canal defect, an oversized puppy lodged in the birth canal, a dead puppy holding up proceedings or a malpresentation in the birth canal. All these represent a medical emergency and your dam needs to be taken to the vet immediately. Administration of Oxytocin at this time will almost certainly result in rupture of the uterus, uterine bleeding and probable death.
  • The bitch appears to have finished whelping and all puppies and placenta’s are accounted for: If this is the case and there is no green discharge but instead a normal reddish brown discharge it should not be necessary to give a *clean out shotThe uterine wall will go through an active phase of self cleansing and the puppies feeding on the dam will stimulate normal Oxytocin release which promote lactation, involution of the uterus and expulsion of any foreign matter, should there be any left behind.
  • Labour is progressing normally and the dam appears to stop but there are more puppies: This is quite normal. Dams often take a rest about half way through whelping and even have a sleep for a few hours before resuming whelping. Additional whelps can be delivered safely up to 36 hours after the initial whelp being born. The requirements for foetal viability are a secure attachment of the placenta to the uterine wall and an adequate oxygen supply. Administering Oxytocin at this time may result in placenta abrupto only rather than the birth of more puppies and the risk of subsequent puppies being born dead due to asphyxiation or foetal distress increases dramatically. If the dam is resting and the remaining puppies are kicking and paddling quite happily in the uterus then allow nature to take its course.
  • The dam is suspected to have Primary Uterine Inertia: This means that the bitch is dilating her cervix but has atony or weak ineffective contractions. This will require a caesarean.

A less aggressive but equally invasive approach is to utilise the dam’s normal body feedback systems in response to certain stimuli to initiate stronger contractions such as stimulation of the “Fergusons Reflex. This involves placing a sterile gloved finger into the vagina and gently feathering the upper wall to initiate an episode of contractions that vary in intensity and time dependant on the degree of uterine fatigue. This may result in the expulsion of another puppy.

INDICATIONS FOR USE:

  • The dam has Secondary Uterine Inertia – this means that the uterine muscles are fatigued and are not producing meaningful contractions. Oxytocin can be administered to increase the intensity of those contractions to expel retained foetuses or placenta’s providing that there is no obstruction or defect in the vaginal canal, the bitch is not mouth breathing, the uterus is not contracting vigorously and there is no evidence of prolonged uterine fatigue as again these all preclude its use. Oxytocin is usually give in conjunction with Glucose and Calcium and these are usually administered by a vet. It must be remembered though that uterine stimulants such as Oxytocin can produce uterine spasm rather than rhythmical contractions resulting in foetal death in utero.
  • If retained placenta’s / membranes are suspected: Oxytocin can be administered as an adjunct to the contractions of the dam to help expel retained membranes or placenta’s within a reasonable time frame to avoid the risk of infection.

Its usual indications for use are:

  1. weak labour
  2. uterine bleeding
  3. post uterine prolapse correction
  4. caesarean section

Other management idea’s to attempt prior to reaching for the Oxytocin shot should include:

  • take the bitch for a short walk on a leash
  • offer the dam some warm milk to drink with some Sandoz in it
  • allow the puppies that have already been born to nurse for 5 – 10 minutes then remove them
  • stimulation of the Ferguson’s Reflex

 

DEFINITIONS:

 

DYSTOCIA: Disturbances in the normal birthing process resulting in difficulties: this can be because of anatomical abnormalities of the dam or puppies or malpresentation of the puppies.

PRIMARY UTERINE INERTIA: Failure to go into Stage2 labour: due to lack of regular +/or effective contractions. It may also be caused by too small or too large a litter. The cervix still dilates.

SECONDARY UTERINE INERTIA: Exhaustion of the uterine muscles: due to poor muscle tone or obesity in the dam or a protracted labour.

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