Oxytocin uses in treatment

OXYTOCIN USE IN TREATMENT

Oxytocin’s affect on the uterus makes it a very important hormone in a horse breeding program.  This naturally occurring compound is released in increasing amounts during the last few days before foaling.  The effect of oxytocin released into the blood stream is to start contractions of the uterus and release milk from the udder.

Oxytocin’s affect on the uterus is to stimulate contraction of the muscles. The uterine muscles are both longitudinal and circular.  The circular muscles tighten around the fetus and the surrounding fluids.  This has the affect of squeezing a water filled balloon. In an attempt to relieve pressure, the fluid filled placenta will search for an escape.  The relaxed cervix waiting for the birth provides the needed escape. As the placenta pushes through the cervix, it widens it which allows more movement, etc.  This in turn stimulates more oxytocin release which starts affecting the longitudinal muscles.  These muscles contract from the ovary end toward the cervix.  This movement of the uterine contents helps to propel them out the cervix.  The continued affect on the uterus after foaling helps the placenta separate from the uterine lining and be passed out.

The above mentioned release of oxytocin also affects the udder. As the blood levels increase we see the udder fill as milk is released from the tissue.  Prior to this let down, the teat ends would almost touch.  With filling by colostrum, the teats will be pointing down, indicating foaling will happen within 24 hours, usually!

Following foaling, each time the foal nudges the udder a signal is sent to the pituitary to release oxytocin.  The affect is to release milk from the udder tissue and into the teats.  Another important affect is the contraction of the uterus, and stimulation of uterine clearance of the products left over from foaling.  Each time the foal nurses, it is helping improve the condition of the uterus and the chances of a successful rebreeding.

We are fortunate to have such an important hormone available for our use.  While it has been around for a very long time, new research is confirming how important it is.  This very versatile drug is used immediately post partum, during treatments and during the breeding process. The dosage is very small and can be given intramuscularly (IM), subcutaneously (SQ), or intravenously (IV).  The onset of action for oxytocin is rapid and its affect on the mare can be seen within minutes. The action and the signs of effectiveness will be discussed below.

During treatment of the uterus, oxytocin helps with uterine clearance.  Small doses stimulate the longitudinal muscle to contract toward the cervix. This helps with removal of the contents of the uterus and stimulates circulation within the walls.  When used in combination with uterine lavage or infusion, the result is a thorough cleansing of the uterus.  

High doses can be counterproductive to the uterus' attempt to cleanse itself. The higher doses will also stimulate the circular muscles.  The result is a reduced affect of the longitudinal muscles and retention of more of the uterine contents.

CLICK  BELOW TO DISPLAY A PRINTER-FRIENDLY COPY OF THIS ARTICLE
Select "Open this file from its current location," if you just want to print it out,
it will open in a simple word processing application, select the print button.
(unless you want to save this article in your computer's memory)
OxytocinUseIntreatment.rtf
Home