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 Equine Pregnancy

استعرض الموضوع السابق استعرض الموضوع التالي اذهب الى الأسفل 
كاتب الموضوعرسالة
ibrahem
طبيب بيطري/عضو الجمعية الطبية البيطرية العراقية
طبيب بيطري/عضو الجمعية الطبية البيطرية العراقية


الدلو عدد المساهمات : 1630
نقاط : 2519
السٌّمعَة : 7
تاريخ الميلاد : 18/02/1960
تاريخ التسجيل : 02/02/2010
العمر : 56
الموقع : مستوصف الوحدة البيطري

مُساهمةموضوع: Equine Pregnancy   الجمعة ديسمبر 03, 2010 10:32 am

Equine Pregnancy

Physiology of Pregnancy

Physiology of Pregnancy

The Early Embryo

At about 24 hours post ovulation the embyro is at 2 cell stage

4-5 days - morula

5-6 days blastocyst

5-6 days enters uterus and zona shed

Capsule forms at blastocyst stage

Protective covering

Origin not clearly known - may be embryonic, may have endometrial contribution

Lost at 21 days






Migration to day 16. The embryo migrates in the uterus for approximately 16 days to release a 'signal' that pregnancy is established. Fixation of the embryo (gestational sac) occurs at about 16 days post ovulation.





Endometrial cups

At about 36-38 days, fetal tissue along the chorionic girdle begin to invade the endometrium and form the endometrial cups.

Endometrial cups secrete eCG ...Equine Chorionic Gonadotrophin (formerly PMSG...Pregnant Mare Serum Gonadotrophin). This acts to luteinize the normal follicular waves that are occurring and results in formation of the secondary corpora lutea.

The cups remain, even if the pregnancy is lost, and are then sloughed at the normal time (120 days).






Equine chorionic gonadotropin (eCG): (formerly pregnant mare serum gonadotropin or PMSG)

Produced by the endometrial cups beginning around d 37-42, peaking around d 60-80, after which the endometrial cups start to decline, disappearing around d 120-150.
The function of the endometrial cups and eCG are unclear.
Some hypothesize an immunologic role in helping to maintain pregnancy.
Causes luteinization of follicular waves to create secondary CLs.
Although eCG has an FSH-like action in many other species, it has LH-like activity in mares.







Secondary CLs

The secondary CLs result in progesterone rise about day 60-120. The endometrial cups regress (they are sloughed from the uterus by an immunologic response).
Secondary vs. accessory CLs (ovulatory or anovulatory)
Progesterone/Progestagens:

Progesterone initially rises, followed by a slight decrease then rises to a peak at d 80, then gradually declining to 1-2 ng/ml during mid-late gestation (d 150).
The second rise is associated with the formation of accessory and secondary CL.
The 5 alpha pregnanes rise from mid gestation to term.
Produced from maternal cholesterol
The fetoplacental unit produces sufficient progestagens so that ovariectomy can be performed after 120-150 d.
Late gestation progestagen rises (last month of pregnancy)
From fetal adrenal production of 5 alpha reduced pregnanes (adrenals do not have 17 alpha hydroxylase)

]

Estrogens
Mare ovarian estrogens begin to rise at day 38-40.
From gonadotrophic stimulation of luteal tissue
Late in gestation maternal estrogen production rises.
At day 70-80 a second rise of estrogens from the fetal-placental unit occurs.
Placental aromatization of the common C-19 precursors
dehydroandrosterone (DHA) and dehydroepiandrosterone (DHEA)
Secreted by fetal gonads.
Fetal estrogens peak at about 210 days and decline and are basal at term.

Placenta

The placenta takes over progestagen (not progesterone) production until foaling. Therefore, a mare does not need her ovaries after about 120 days of gestation.
The mare has diffuse type of microcotyledonary placenta
Complete placental formation is done at 150 days.

Pregnancy Diagnosis

Certain characteristics of pregnancy in the mare aid in diagnosis.
Progesterone causes increased tone of the uterus and cervix.
Estrogen from the conceptus, in conjunction with the progesterone results in exaggerated tone.
The vesicle is spherical and distinct, and can be palpated from 18 d (+) through 60-70 d, and seen with ultrasound beginning at 10 or 12 d (depending on the machine).








Other significant characteristics of equine pregnancy include the presence of chorionic girdle cells from the fetal trophoblast which invade the endometrium. The ovaries are active during pregnancy, with large follicles palpable especially around 18-23 d and 36-45 d.


Hormones


Estrogens

Estrogens are primarily from the fetal gonads in late pregnancy.
The fetal gonads increase in size and are larger than the maternal gonads at 8 mos. gestation, decreasing in size after 300 d.
Estrogens appear in the mare's urine in large amounts in the latter half of gestation.
Estrone sulfate: Derived from the placenta, it is an indicator of fetal viability. It declines within a few days of fetal death.


Methods of diagnosis
Palpation per rectum
Cervical changes from 16 or 17 d to term are elongation, firmness and tubularity. The uterus also has increased tone.
The chorionic vesicle is distinct and spherical and approximate sizes are:
28 d (4 wks) Key lime (pullet egg)
35 d (5 wks) lemon
42 d (6 wks) orange
49 d (7 wks) grapefruit
56 d (8 wks) cantaloupe
By 90 d it is hard to delineate the cranial margin of uterus.
Fetal Ballotment per rectum becomes consistent after 150d.
Aging fetus by size, as in the cow, is imprecise.
Differentials which may confuse the examiner include the bladder and enlargement in the non pregnant tract at the base of the uterine horn.


Ultrasound

The time of earliest diagnosis depends on the MHZ of the probe.
Gestational age can be estimated from the size of the vesicle.
There is a plateau in the growth curve between d 17-24 during which the size does not increase much.








Movement of the vesicle is characteristic of early pregnancy, covering the entire uterus and moving surprisingly rapidly.
Movement ceases around d 16-17 when "fixation" occurs.



Movement of the equine embryo.

The fetal heartbeat can be observed around d 23-24.





The vesicle undergoes a series of changes, having a very characteristic appearance at various stages with which the examiner should be familiar.
The vesicle usually becomes fixed in a location at the base of a uterine horn.
Although initially spherical, the shape becomes more triangular around d 18 and the embryo becomes visible around d 20-21, usually in a ventral location.
Changes in the shape of the vesicle and the characteristic location of the embryo are related to the developing trophoblast.
At d 21, the embryo is at the bottom of vesicle and the entire hypoechoic structure is the yolk sac.
Soon thereafter the developing allantoic membrane can be seen.
By d 30 the embryo is found in the middle of the vesicle suspended by the developing allantoic membrane, with the allantoic sac beneath and the yolk sac above.
By d 36 the embryo is near the top of the vesicle and the yolk sac is all but gone.
By d 40 the embryo is back in the middle of the vesicle, suspended by the umbilicus.
Vesicles that are smaller than normal size for their age are associated with increased rates of embryonic loss.
One of the critical reasons for a thorough early pregnancy exam is to detect twins, which will be discussed in more detail later.

Fetal sexing


Fetal sexing is becoming more and more in demand.
Numerous reasons exist for owners desiring knowledge of the sex of the fetus, such as appraisals, insurance coverage, payment of stud fees, sales consignments, mating lists, sale or purchase, etc.
The veterinarian performing fetal sexing should be aware of the liability implications involved.
Gender determination is based on the location of the genital tubercle.
The genital tubercle is the precursor of the penis in the male or the clitoris in the female.
The tubercle migrates toward the umbilicus in the male and toward the anus in the female.
Ideal times for performing the procedure are from 59 to 68 days or 5 to 6 months.
Before 58 days the tubercle is not distinct enough and has not migrated sufficiently to make a distinction.
After 70 days the fetus is hard to reach until it is approximately 3.5 to 4 months of age.
As the fetus gets larger, a trans-abdominal approach may be preferred.
It is important to mention that accuracy is based on certainty and that the veterinarian should keep their own written records. If cattle are available, it is easier to learn the technique on cattle because the manipulations are easier and they are more tolerant of prolonged rectal examinations.

Indirect pregnancy tests

The presence of eCG has been used as a test for pregnancy because it is only found in pregnant mares.
The problem is that it remains elevated after the cups are formed even if fetal death occurs. In house tests are available which makes them attractive in some situations (e.g. miniature horses).
For example, with the Synbiotics test, it is reported that 20% of samples are positive at 30 d, 66% at 38 d, 76% at 40 d, and 92% at 42 d




Endometrial cups in a mare.

Estrogens are elevated 150 d to term (due to production from fetal gonads).
The Cuboni test, based on fluorescence of urine, is 90% accurate after 100 d, 100% accurate after 150 d.
Generally, that late in gestation, other means of pregnancy diagnosis have already been employed.
Early Pregnancy Factor
Check this link out to a potentially exciting method to determine pregnancy.
EPF - two components
EPF-A - Uterine tube
EPF -B - Ovary
Production requires signal from fertilized ovum (ovum factor) released under prolactin presence after sperm penetration.
Appears 4-6 hours
Disappears with fetal death
Non-detectable at 20 days in milk and 30 days in serum
Lateral flow dipstick test
It does not work in the cow, so I have doubts in the mare.
I have seen no refereed papers about its use in the mare.


Problems of Pregnancy
Uterine torsion

Uterine torsion is an uncommon problem, found usually late in gestation (7 mo to term) but not usually at parturition (unlike the cow).
It is thought that the reduced incidence in the mare can be attributed at least in part to anatomical differences from the cow in the attachments of the uterus to the body wall by the broad ligament and to the method of rising (front end first as opposed to cow).
The clinical signs are those of colic.
Diagnosis is made by rectal palpation.
The broad ligaments are crossed, one going over the uterus, the other below.
The location of the ovaries is abnormal as well.
A vaginal exam is usually not very helpful, as the vagina and cervix are rarely involved.
Treatment is generally surgical via either a standing flank laparotomy or midline laparotomy.
After correction, the pregnancy is allowed to continue to term.
Rolling has also been reported (JAVMA 193:3, p337).
In that report, 6 of 7 were successfully corrected, with 1 uterine rupture (355 d gestation, previous attempt at correction).


Prepubic tendon rupture

More commonly seen in older, heavier (draft) mares, it is not common in athletic breeds.
There is probably not really an actual pre-pubic tendon. It is really a tear in the muscle.
The first sign is ventral edema.
This is followed by a "Dropped" abdomen






The mammary secretions may become bloody.





Treatment consists of abdominal support and reducing activity. Parturition or induced or assisted or an elective C-section has been the traditional treatment. A report from U Penn (JAVMA 232:257-261, 2008) indicates that a conservative approach (wait and let the mare foal) may result in better mare and foal prognosis.
The prognosis is poor for survival of both the dam and the fetus.


Obstetrics
Normally parturition occurs at night, and the mare seemingly can delay parturition until the setting suits her.
Horses have a very variable gestation length (ave 335, range 305-405).
It is a very rapid process. Often being completed in less than 20 min.

Signs of impending parturition in the mare

Udder development is evident 3 to 6 wks prior to foaling.
"Waxing" or the presence of a very thick drop of sticky colostrum at the teat end, can be observed 1-72 h prior to parturition.





Some mares may leak colostrum for days, to the extent that insufficient good quality colostrum is available when the foal is born.
There is slight relaxation of the sacrosciatic ligaments but this is not as evident as in cows, especially in the heavily muscled breeds like Quarter Horses.
The vulva becomes edematous and lengthens.
Most importantly, there is a change in the electrolytes in the mammary secretions.
Sodium decreases,




Potassium and magnesium increase





Calcium increases sharply.




A point system based on these changes was developed by Ousey et al. to aid in predicting foaling. Others watch for the crossing of the sodium and potassium curves in addition to elevated calcium.
Equine Pregnancy
103-153, 157-165, 177-178






Physiology of Pregnancy

The Early Embryo

At about 24 hours post ovulation the embyro is at 2 cell stage

4-5 days - morula

5-6 days blastocyst

5-6 days enters uterus and zona shed

Capsule forms at blastocyst stage

Protective covering

Origin not clearly known - may be embryonic, may have endometrial contribution

Lost at 21 days





Migration to day 16. The embryo migrates in the uterus for approximately 16 days to release a 'signal' that pregnancy is established. Fixation of the embryo (gestational sac) occurs at about 16 days post ovulation.








Endometrial cups

At about 36-38 days, fetal tissue along the chorionic girdle begin to invade the endometrium and form the endometrial cups.

Endometrial cups secrete eCG ...Equine Chorionic Gonadotrophin (formerly PMSG...Pregnant Mare Serum Gonadotrophin). This acts to luteinize the normal follicular waves that are occurring and results in formation of the secondary corpora lutea.

The cups remain, even if the pregnancy is lost, and are then sloughed at the normal time (120 days).






Equine chorionic gonadotropin (eCG): (formerly pregnant mare serum gonadotropin or PMSG)

Produced by the endometrial cups beginning around d 37-42, peaking around d 60-80, after which the endometrial cups start to decline, disappearing around d 120-150.
The function of the endometrial cups and eCG are unclear.
Some hypothesize an immunologic role in helping to maintain pregnancy.
Causes luteinization of follicular waves to create secondary CLs.
Although eCG has an FSH-like action in many other species, it has LH-like activity in mares.





Secondary CLs

The secondary CLs result in progesterone rise about day 60-120. The endometrial cups regress (they are sloughed from the uterus by an immunologic response).
Secondary vs. accessory CLs (ovulatory or anovulatory)
Progesterone/Progestagens:

Progesterone initially rises, followed by a slight decrease then rises to a peak at d 80, then gradually declining to 1-2 ng/ml during mid-late gestation (d 150).
The second rise is associated with the formation of accessory and secondary CL.
The 5 alpha pregnanes rise from mid gestation to term.
Produced from maternal cholesterol
The fetoplacental unit produces sufficient progestagens so that ovariectomy can be performed after 120-150 d.
Late gestation progestagen rises (last month of pregnancy)
From fetal adrenal production of 5 alpha reduced pregnanes (adrenals do not have 17 alpha hydroxylase)




Estrogens

Mare ovarian estrogens begin to rise at day 38-40.
From gonadotrophic stimulation of luteal tissue
Late in gestation maternal estrogen production rises.
At day 70-80 a second rise of estrogens from the fetal-placental unit occurs.
Placental aromatization of the common C-19 precursors
dehydroandrosterone (DHA) and dehydroepiandrosterone (DHEA)
Secreted by fetal gonads.
Fetal estrogens peak at about 210 days and decline and are basal at term.

Placenta

The placenta takes over progestagen (not progesterone) production until foaling. Therefore, a mare does not need her ovaries after about 120 days of gestation.
The mare has diffuse type of microcotyledonary placenta
Complete placental formation is done at 150 days.
Equine Placentation adopted from Ginther

Day 9-10
Inner cell mass (brown)

Yolk sac starting

Day 14
Still mobile

Mesoderm will be blood vessels and connective tissue.



Day 16
Folds start to form over embryonic disc to form amnion.

Day 48-19
Amnion has formed.

Note the two and three layered areas.



Day 21
Allantois is emerging.

Day 25
Allantois has moved over embyro.

Heart beat present.

Note red developing chorionic girdle.

Day 30
Note red chorionic girdle which will form the endometrial cups.

Day 40
Embryo moved to opposite pole.

Yolk sac replaced by allantois.

Day 80
The yolk sac is only a remnant.

Conceptus fills both horns.



Pregnancy Diagnosis

Certain characteristics of pregnancy in the mare aid in diagnosis.
Progesterone causes increased tone of the uterus and cervix.
Estrogen from the conceptus, in conjunction with the progesterone results in exaggerated tone.
The vesicle is spherical and distinct, and can be palpated from 18 d (+) through 60-70 d, and seen with ultrasound beginning at 10 or 12 d (depending on the machine).






Other significant characteristics of equine pregnancy include the presence of chorionic girdle cells from the fetal trophoblast which invade the endometrium. The ovaries are active during pregnancy, with large follicles palpable especially around 18-23 d and 36-45 d.



Hormones




Estrogens

Estrogens are primarily from the fetal gonads in late pregnancy.
The fetal gonads increase in size and are larger than the maternal gonads at 8 mos. gestation, decreasing in size after 300 d.
Estrogens appear in the mare's urine in large amounts in the latter half of gestation.
Estrone sulfate: Derived from the placenta, it is an indicator of fetal viability. It declines within a few days of fetal death.








Click on the BET labs icon to see their web page and find out what hormones they run.

External signs of pregnancy

Although abdominal enlargement is characteristic of pregnancy, it is unreliable as a diagnostic sign.
Ballotment or observed movements of the fetus can often be seen late in gestation.
Mammary changes are quite variable.
Pelvic changes (relaxation of the pelvic ligaments) occur late in gestation but are often difficult to detect.
Cessation of estrus behavior is variable and unreliable.
Some mares will continue to show estrus even when pregnant.


Methods of diagnosis
Palpation per rectum
Cervical changes from 16 or 17 d to term are elongation, firmness and tubularity. The uterus also has increased tone.
The chorionic vesicle is distinct and spherical and approximate sizes are:
28 d (4 wks) Key lime (pullet egg)
35 d (5 wks) lemon
42 d (6 wks) orange
49 d (7 wks) grapefruit
56 d (8 wks) cantaloupe
By 90 d it is hard to delineate the cranial margin of uterus.
Fetal Ballotment per rectum becomes consistent after 150d.
Aging fetus by size, as in the cow, is imprecise.
Differentials which may confuse the examiner include the bladder and enlargement in the non pregnant tract at the base of the uterine horn.


Ultrasound

The time of earliest diagnosis depends on the MHZ of the probe.
Gestational age can be estimated from the size of the vesicle.
There is a plateau in the growth curve between d 17-24 during which the size does not increase much.


Movement of the vesicle is characteristic of early pregnancy, covering the entire uterus and moving surprisingly rapidly.
Movement ceases around d 16-17 when "fixation" occurs.

Movement of the equine embryo.

The fetal heartbeat can be observed around d 23-24.

The vesicle undergoes a series of changes, having a very characteristic appearance at various stages with which the examiner should be familiar.
The vesicle usually becomes fixed in a location at the base of a uterine horn.
Although initially spherical, the shape becomes more triangular around d 18 and the embryo becomes visible around d 20-21, usually in a ventral location.
Changes in the shape of the vesicle and the characteristic location of the embryo are related to the developing trophoblast.
At d 21, the embryo is at the bottom of vesicle and the entire hypoechoic structure is the yolk sac.
Soon thereafter the developing allantoic membrane can be seen.
By d 30 the embryo is found in the middle of the vesicle suspended by the developing allantoic membrane, with the allantoic sac beneath and the yolk sac above.
By d 36 the embryo is near the top of the vesicle and the yolk sac is all but gone.
By d 40 the embryo is back in the middle of the vesicle, suspended by the umbilicus.
Vesicles that are smaller than normal size for their age are associated with increased rates of embryonic loss.
One of the critical reasons for a thorough early pregnancy exam is to detect twins, which will be discussed in more detail later.

Fetal sexing


Fetal sexing is becoming more and more in demand.
Numerous reasons exist for owners desiring knowledge of the sex of the fetus, such as appraisals, insurance coverage, payment of stud fees, sales consignments, mating lists, sale or purchase, etc.
The veterinarian performing fetal sexing should be aware of the liability implications involved.
Gender determination is based on the location of the genital tubercle.
The genital tubercle is the precursor of the penis in the male or the clitoris in the female.
The tubercle migrates toward the umbilicus in the male and toward the anus in the female.
Ideal times for performing the procedure are from 59 to 68 days or 5 to 6 months.
Before 58 days the tubercle is not distinct enough and has not migrated sufficiently to make a distinction.
After 70 days the fetus is hard to reach until it is approximately 3.5 to 4 months of age.
As the fetus gets larger, a trans-abdominal approach may be preferred.
It is important to mention that accuracy is based on certainty and that the veterinarian should keep their own written records. If cattle are available, it is easier to learn the technique on cattle because the manipulations are easier and they are more tolerant of prolonged rectal examinations.

Indirect pregnancy tests

The presence of eCG has been used as a test for pregnancy because it is only found in pregnant mares.
The problem is that it remains elevated after the cups are formed even if fetal death occurs. In house tests are available which makes them attractive in some situations (e.g. miniature horses).
For example, with the Synbiotics test, it is reported that 20% of samples are positive at 30 d, 66% at 38 d, 76% at 40 d, and 92% at 42 d.

Endometrial cups in a mare.

Estrogens are elevated 150 d to term (due to production from fetal gonads).
The Cuboni test, based on fluorescence of urine, is 90% accurate after 100 d, 100% accurate after 150 d.
Generally, that late in gestation, other means of pregnancy diagnosis have already been employed.

Cuboni test.

Estrone sulfate can be tested for in almost any bodily fluid. In serum there is a sharp rise after 60 d, peak levels by 80 d.
Before 60 d a false positive can be obtained due to estrus. In milk a similar pattern is observed, only with lower values.
It is considered an indicator of fetal viability after 44 d. In feces, it can be found after 4 mos. And can also be found in urine. Testing is noninvasive and therefore used in studies of wild equids.
Commercial tests available "Equi Test - ES" (www.trideltaltd.com); "Confirm" (http://www.icpbio.com/site.aspx/Pages/Products/ConfirmEquine)

Early Pregnancy Factor
Check this link out to a potentially exciting method to determine pregnancy.
EPF - two components
EPF-A - Uterine tube
EPF -B - Ovary
Production requires signal from fertilized ovum (ovum factor) released under prolactin presence after sperm penetration.
Appears 4-6 hours
Disappears with fetal death
Non-detectable at 20 days in milk and 30 days in serum
Lateral flow dipstick test
It does not work in the cow, so I have doubts in the mare.
I have seen no refereed papers about its use in the mare.




Problems of Pregnancy
Uterine torsion

Uterine torsion is an uncommon problem, found usually late in gestation (7 mo to term) but not usually at parturition (unlike the cow).
It is thought that the reduced incidence in the mare can be attributed at least in part to anatomical differences from the cow in the attachments of the uterus to the body wall by the broad ligament and to the method of rising (front end first as opposed to cow).
The clinical signs are those of colic.
Diagnosis is made by rectal palpation.
The broad ligaments are crossed, one going over the uterus, the other below.
The location of the ovaries is abnormal as well.
A vaginal exam is usually not very helpful, as the vagina and cervix are rarely involved.
Treatment is generally surgical via either a standing flank laparotomy or midline laparotomy.
After correction, the pregnancy is allowed to continue to term.
Rolling has also been reported (JAVMA 193:3, p337).
In that report, 6 of 7 were successfully corrected, with 1 uterine rupture (355 d gestation, previous attempt at correction).


Prepubic tendon rupture

More commonly seen in older, heavier (draft) mares, it is not common in athletic breeds.
There is probably not really an actual pre-pubic tendon. It is really a tear in the muscle.
The first sign is ventral edema.
This is followed by a "Dropped" abdomen.




The mammary secretions may become bloody.


Treatment consists of abdominal support and reducing activity. Parturition or induced or assisted or an elective C-section has been the traditional treatment. A report from U Penn (JAVMA 232:257-261, 2008) indicates that a conservative approach (wait and let the mare foal) may result in better mare and foal prognosis.
The prognosis is poor for survival of both the dam and the fetus.


Obstetrics
Normally parturition occurs at night, and the mare seemingly can delay parturition until the setting suits her.
Horses have a very variable gestation length (ave 335, range 305-405).
It is a very rapid process. Often being completed in less than 20 min.

Signs of impending parturition in the mare

Udder development is evident 3 to 6 wks prior to foaling.
"Waxing" or the presence of a very thick drop of sticky colostrum at the teat end, can be observed 1-72 h prior to parturition.


Some mares may leak colostrum for days, to the extent that insufficient good quality colostrum is available when the foal is born.
There is slight relaxation of the sacrosciatic ligaments but this is not as evident as in cows, especially in the heavily muscled breeds like Quarter Horses.
The vulva becomes edematous and lengthens.
Most importantly, there is a change in the electrolytes in the mammary secretions.
Sodium decreases,


Potassium and magnesium increase,




Calcium increases sharply.


A point system based on these changes was developed by Ousey et al. to aid in predicting foaling. Others watch for the crossing of the sodium and potassium curves in addition to elevated calcium.



The most important change is an increase in divalent cations (Ca++, Mg++) in milk.
The increase in magnesium is more gradual and occurs earlier pre-partum than Ca++. It is the increase in Ca++ that is most useful.
When calcium rises >10 mmol or 400 ppm, parturition is imminent



Characteristics of parturition in mares

Stage 1 is characterized by restlessness, walking, frequent urination, sweating, the mare is anxious, looking at her abdomen, getting up and laying down, rolling.
Most mares will rise at least once after going down, but repeatedly getting up and down may signal a problem.
The foal has an active role in its final positioning, going from dorso-pubic to dorso-sacral.
The duration of Stage 1 is usually about an hour or a little longer (10 min - 5.5 h).
Stage 1 ends with the rupture of the chorio-allantois at the cervical star.
Stage 2 consists of 15 to 30 min of very forceful expulsive efforts.
The foal is presented in the intact amnion, usually with one forelimb about 6 in. behind the other.
The long umbilical cord remains intact until the mare rises.
It was once thought that significant blood flow, up to 1 liter, occurred through the cord after birth and people were cautioned about breaking the cord too soon.
However, more recent studies have shown that there is no significant blood flow in the cord after birth and there is no difference in the PCV between foals in which the cord is broken soon after birth and those in which the cord is left intact.
Stage 3 typically appears as a tranquilizing effect post-delivery.
The placenta is usually passed in less than 3 h after parturition.
After delivery, the navel should be disinfected with 2% chlorhexidine.
Non-tamed iodine is associated with an increased incidence of patent urachus, and other problems because it is too harsh.
Povidone iodine does not disinfect adequately.
Good colostrum has a specific gravity >1.06 and adequate intake should be observed. Inspection of the placenta should be routine.
Make sure that all the placenta has been passed.
Check for signs of placentitis. Any abnormal areas may indicate septicemia of the foal.
Treatment should begin immediately, before clinical signs appear in the foal. Also check for other abnormalities in the placenta. Areas of aplastic or hypoplastic villi are an indication of uterine pathology.

منقول

_________________
من السهل أن تحب الناس ولكن من الصعب أن تجبر الناس على حبك

الرجوع الى أعلى الصفحة اذهب الى الأسفل
Dr. Tuhfa
مشرفة قسم الشعر والنثر
مشرفة قسم الشعر والنثر


الثور عدد المساهمات : 1526
نقاط : 1858
السٌّمعَة : 31
تاريخ الميلاد : 20/05/1987
تاريخ التسجيل : 20/03/2010
العمر : 29
الموقع : ♥ღϠ₡ღ♥. ماجستير - أحياء مجهرية - كلية الطب - جامعة تكريت ♥ღϠ₡ღ♥

مُساهمةموضوع: رد: Equine Pregnancy   الجمعة ديسمبر 17, 2010 4:07 pm



Thank you so much Doctor Ibraheem
Fabulous..




_________________

ܓܛܟܓܛܟ

Ϡ₡ Dr. Tuhfa Ϡ₡


***
الرجوع الى أعلى الصفحة اذهب الى الأسفل
http://www.veterinaryknowledge.com/f7-montada
ibrahem
طبيب بيطري/عضو الجمعية الطبية البيطرية العراقية
طبيب بيطري/عضو الجمعية الطبية البيطرية العراقية


الدلو عدد المساهمات : 1630
نقاط : 2519
السٌّمعَة : 7
تاريخ الميلاد : 18/02/1960
تاريخ التسجيل : 02/02/2010
العمر : 56
الموقع : مستوصف الوحدة البيطري

مُساهمةموضوع: رد: Equine Pregnancy   الجمعة ديسمبر 17, 2010 7:20 pm

شكرا تحفة الوردة لمرورك الكريم


تحياتي

_________________
من السهل أن تحب الناس ولكن من الصعب أن تجبر الناس على حبك

الرجوع الى أعلى الصفحة اذهب الى الأسفل
 
Equine Pregnancy
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