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Parturition Pharmacological Manipulation - Anatomy & Physiology (view source)
Revision as of 11:35, 3 September 2008
, 11:35, 3 September 2008no edit summary
{{toplink
|backcolour =EED2EE
|linkpage =Reproductive System - Anatomy & Physiology
|linktext =Reproductive System
|maplink = Reproductive System (Content Map) - Anatomy & Physiology
|pagetype =Anatomy
|sublink1=Reproductive System - Anatomy & Physiology#Parturition
|subtext1=PARTURITION
}}
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[[Image:Parturition Pharmacology summary.jpg|thumb|right|150px|Summary of Treatments,Copyright RVC 2008]]
[[Image:Parturition Pharmacology summary.jpg|thumb|right|150px|Summary of Treatments,Copyright RVC 2008]]
= Why Control Timing of Parturition? =
== Why Control Timing of Parturition? ==
== Herds ==
=== Herds ===
* Improves supervision to ensure the farmer can be around at the time of parturition.
* Improves supervision to ensure the farmer can be around at the time of parturition.
* Tightens the calving interval in cattle.
* Tightens the calving interval in cattle.
== Individuals ==
=== Individuals ===
* Maternal emergrncy such as abnormal foetal position, bone fracture of the pelvis etc.
* Maternal emergrncy such as abnormal foetal position, bone fracture of the pelvis etc.
* Foetal abnormality, or an oversized foetus.
* Foetal abnormality, or an oversized foetus.
= Disadvantages of Parturition Induction =
== Disadvantages of Parturition Induction ==
* Timing may not be absolutely perfect, there is considerable variation in the timing of drug action and effect.
* Timing may not be absolutely perfect, there is considerable variation in the timing of drug action and effect.
* Increased incidence of clinical post-parturient uterine infections.
* Increased incidence of clinical post-parturient uterine infections.
= Requirements for Parturition Induction =
== Requirements for Parturition Induction ==
You must ensure the foetus is appropriately developed before inducing parturition. The lungs must be mature to enable survival. Naturally maturation of the lungs is induced by foetal cortisol, so it may be useful to administer '''glucocorticoids''' to artificially mature the lungs.
You must ensure the foetus is appropriately developed before inducing parturition. The lungs must be mature to enable survival. Naturally maturation of the lungs is induced by foetal cortisol, so it may be useful to administer '''glucocorticoids''' to artificially mature the lungs.
* COX II increases during labour, so prostaglandins will form as long as arachidonic acid is available.
* COX II increases during labour, so prostaglandins will form as long as arachidonic acid is available.
= Drugs Influencing Uterine Activity =
== Drugs Influencing Uterine Activity ==
== Ecbolic Drugs ==
=== Ecbolic Drugs ===
* Induce parturition by uterine activation.
* Induce parturition by uterine activation.
=== Ergot Alkaloids ===
==== Ergot Alkaloids ====
* Induce contraction
* Induce contraction
* Ergonavine taken off the market, Methergine is the only derivative in use.
* Ergonavine taken off the market, Methergine is the only derivative in use.
=== PGF2α Analogues ===
==== PGF2α Analogues ====
* Dinoprost
* Dinoprost
* Exert action over a long period of time.
* Exert action over a long period of time.
=== Oxytocin ===
==== Oxytocin ====
* Used in conjuction with Oestradiol Benzoate
* Used in conjuction with Oestradiol Benzoate
** Inhibits uterine activity, but sensitizes the [[Female_Reproductive_Tract_-The_Uterus_-_Anatomy_%26_Physiology|uterus]] to oxytocin.
** Inhibits uterine activity, but sensitizes the [[Female_Reproductive_Tract_-The_Uterus_-_Anatomy_%26_Physiology|uterus]] to oxytocin.
== Tocolytic Drugs ==
=== Tocolytic Drugs ===
* Delay parturition by relaxation of the uterine myometrium.
* Delay parturition by relaxation of the uterine myometrium.
=== Progesterone ===
==== Progesterone ====
* Slow acting steroid through nuclear receptors.
* Slow acting steroid through nuclear receptors.
* Not useful in emergency situations.
* Not useful in emergency situations.
=== Relaxin ===
==== Relaxin ====
* Rapidly acting peptide hormone
* Rapidly acting peptide hormone
The autonomic nervous system is not important in normal labour, since uterine contractions are controlled by the [[Endocrine_System_-_Pituitary_Gland_-_Anatomy_%26_Physiology#Parturition|neuroendocrine release of oxytocin]]. However, the autonomic nervous system can be used to control parturition pharmacologically by changing cAMP levels which effects the myometrium.
The autonomic nervous system is not important in normal labour, since uterine contractions are controlled by the [[Endocrine_System_-_Pituitary_Gland_-_Anatomy_%26_Physiology#Parturition|neuroendocrine release of oxytocin]]. However, the autonomic nervous system can be used to control parturition pharmacologically by changing cAMP levels which effects the myometrium.
== Sympathetic ==
=== Sympathetic ===
=== α Adrenoceptors ===
==== α Adrenoceptors ====
* Induce contractions
* Induce contractions
* Antagonists delay parturition
* Antagonists delay parturition
=== β Adrenoceptors ===
==== β Adrenoceptors ====
* Progesterone increases the number of β Adrenoceptors
* Progesterone increases the number of β Adrenoceptors
* Antagonists induce parturition e.g. Carazolol
* Antagonists induce parturition e.g. Carazolol
== Parasympathetic ==
=== Parasympathetic ===
* Acetylcholine inhibits contractions
* Acetylcholine inhibits contractions
= Induction of Parturition =
== Induction of Parturition ==
== Cow ==
=== Cow ===
=== To Induce Parturition ===
==== To Induce Parturition ====
==== Corticosteroids ====
===== Corticosteroids =====
* Mimic foetal cortisol to remove the progesterone block by upregulating enzymes that will increase the oestrogen:progesterone ratio (for more information see [[Parturition_-_Endocrine_Control_of_Parturition_-_Anatomy_%26_Physiology|endocrinology of parturition]]).
* Mimic foetal cortisol to remove the progesterone block by upregulating enzymes that will increase the oestrogen:progesterone ratio (for more information see [[Parturition_-_Endocrine_Control_of_Parturition_-_Anatomy_%26_Physiology|endocrinology of parturition]]).
* '''Medium-Long Acting''': apply 2-3 weeks before the due date. Administration after 260 days will cause no advance of the calving date. Administration before 260 days will cause neonatal mortality. Thus use of these corticosteroids is reliant upon accurate record keeping by the farmer so that exact dates are known.
* '''Medium-Long Acting''': apply 2-3 weeks before the due date. Administration after 260 days will cause no advance of the calving date. Administration before 260 days will cause neonatal mortality. Thus use of these corticosteroids is reliant upon accurate record keeping by the farmer so that exact dates are known.
==== Corticosteroid & PGF2α Analogue ====
===== Corticosteroid & PGF2α Analogue =====
* Has the additional benefit of acting to [[Parturition_-_Cervical_Softening_-_Anatomy_%26_Physiology|dilate and soften the cervix]] to facillitate delivery.
* Has the additional benefit of acting to [[Parturition_-_Cervical_Softening_-_Anatomy_%26_Physiology|dilate and soften the cervix]] to facillitate delivery.
==== PGF2α Analogue Alone ====
===== PGF2α Analogue Alone =====
* Causes luteolysis to remove the progesterone block.
* Causes luteolysis to remove the progesterone block.
* However, it risks inadequate foetal maturation upon delivery.
* However, it risks inadequate foetal maturation upon delivery.
=== To Delay Parturition ===
==== To Delay Parturition ====
* Useful in valuable cows coming in to calf too early.
* Useful in valuable cows coming in to calf too early.
* Administer a β Adrenoceptor agonist such as Clenbuterol.
* Administer a β Adrenoceptor agonist such as Clenbuterol.
== Sow ==
=== Sow ===
* Widespread use
* Widespread use
==== PGF2α Analogue ====
===== PGF2α Analogue =====
* Administer 2 days before the mean [[Reproductive_System#Gestation|gestation]] of the herd.
* Administer 2 days before the mean [[Reproductive_System#Gestation|gestation]] of the herd.
* Used to ensure tight farrowing
* Used to ensure tight farrowing
==== PGF2α Analogue + Oxytocin ====
===== PGF2α Analogue + Oxytocin =====
* Favoured method
* Favoured method
* The oxytocin increases milk production and ensures delivery of the [[Gestation_-Placenta_-_Anatomy_%26_Physiology|placenta]].
* The oxytocin increases milk production and ensures delivery of the [[Gestation_-Placenta_-_Anatomy_%26_Physiology|placenta]].
==== β Adrenergic Antagonist ====
===== β Adrenergic Antagonist =====
* Administer in the first stage of labour.
* Administer in the first stage of labour.
* Decreases the incidence of stillbirths
* Decreases the incidence of stillbirths
==== Progesterone ====
===== Progesterone =====
* Delays parturition by 1.5-3 days
* Delays parturition by 1.5-3 days
==== Oxytocin ====
===== Oxytocin =====
* Administer postpartum to increase uterine involution and milk production.
* Administer postpartum to increase uterine involution and milk production.
== Mare ==
=== Mare ===
Drugs are used in individuals with a history of difficult birth and in emergency situations, The mare must be 320-330 days pregnant to ensure adequate maturity of the foetus. Also, the [[Lactation_-_The_Mammary_Gland_-_Anatomy_%26_Physiology|mammary gland]] must be developed and contain [[Lactation_-_Milk_Composition_and_Biosynthesis-_Anatomy_%26_Physiology#Colostrum|colostrum]]. The [[Lactation_-_The_Mammary_Gland_-_Anatomy_%26_Physiology|mammary gland]] is a good indicator of foetal maturity. Mammary secretion of calcium carbonate increases 24 hours before foaling. So, calcium carbonate levels can be used to assess foetal maturity prior to induction. Mammary secretions are generally tested using a titret kit. A disadvantage of this is that essential immunoglobulins can be lost by this pre-parturient release of colostrum, resulting in the foal receiving less colostrum on its first suckle.
Drugs are used in individuals with a history of difficult birth and in emergency situations, The mare must be 320-330 days pregnant to ensure adequate maturity of the foetus. Also, the [[Lactation_-_The_Mammary_Gland_-_Anatomy_%26_Physiology|mammary gland]] must be developed and contain [[Lactation_-_Milk_Composition_and_Biosynthesis-_Anatomy_%26_Physiology#Colostrum|colostrum]]. The [[Lactation_-_The_Mammary_Gland_-_Anatomy_%26_Physiology|mammary gland]] is a good indicator of foetal maturity. Mammary secretion of calcium carbonate increases 24 hours before foaling. So, calcium carbonate levels can be used to assess foetal maturity prior to induction. Mammary secretions are generally tested using a titret kit. A disadvantage of this is that essential immunoglobulins can be lost by this pre-parturient release of colostrum, resulting in the foal receiving less colostrum on its first suckle.
* Corticosteroids are NOT effective and prostaglandin results in abdominal pain.
* Corticosteroids are NOT effective and prostaglandin results in abdominal pain.
=== Low dose Oxytocin ===
==== Low dose Oxytocin ====
* Induces foaling in ~90 minutes.
* Induces foaling in ~90 minutes.
== Ewe ==
=== Ewe ===
* Prostaglandin analogues are NOT active. They cause luteolysis, but do not remove the progesterone block due to placental progesterone production.
* Prostaglandin analogues are NOT active. They cause luteolysis, but do not remove the progesterone block due to placental progesterone production.
=== Short Acting Corticosteroids ===
==== Short Acting Corticosteroids ====
* Administer on day 144 of [[Reproductive_System#Gestation|gestation]].
* Administer on day 144 of [[Reproductive_System#Gestation|gestation]].
* Risks delivery of low weight lambs.
* Risks delivery of low weight lambs.
== Bitch and Queen ==
=== Bitch and Queen ===
* Induction is rare
* Induction is rare
* Caesarian more commonly implicated
* Caesarian more commonly implicated
=== Low Dose Oxytocin ===
==== Low Dose Oxytocin ====
* Initiates myometrial contractions.
* Initiates myometrial contractions.