a guide for ultrasonographic examination of the mare

A guide for ultrasonographic examination of the mare reproductive

system

By

Dr. Derar Refaat IbrahimLecturer of Theriogenology

Dept. TheriogenologyFac. Vet. Med.

Assiut UniversityCode- 059-I0


system

By





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بسم االله الرحمن الرحيم

والخيل والبغال والحمير لترآبوها ”“و زينة ويخلق ما لا تعلمون

صدق االله العظيم

)8(سورة النحل اية


Ultrasonic exam of

the Mare


• A key feature of the reproductive examination is the ultrasound

exam. With the ultrasound, you are able to see much more than

you can feel.

• Ultrasonography is used for diagnosis and management in almost

every aspect of breeding management.

Ovaries

• Examination of the ovaries can aid in determining the stage of the

cycle and in predicting or identifying impending ovulation.

Characteristics of the ovaries at the various stages of the estrous

cycle are:

o Anestrus: small ovaries, absence of a corpus luteum (CL), no

follicles > 20 mm

OvaryOvary


o Transition: ovaries of variable size, absence of a CL, follicles

> 25 mm present

o Estrus: ovaries of variable size, absence of an active CL,

may see regressed CL, follicles > 25 mm present, usually 1,

occasionally 2, large (dominant) follicle present

o

o

o

F

F

F

FF

F

F

F

DF


o Luteal (Diestrus): early - evidence of recent ovulation; later -

ovaries of variable size, follicles may be present and can be

large, CL present

Ovulation

• Various parameters have been investigated in an attempt to predict

with accuracy the time of ovulation. By palpation, the estimation of

follicular size and softness are the parameters used.

• Increase in follicular size:

• Change in follicular shape:

CL

Ovary


o follicles will frequently develop a "pear-shaped" appearance

shortly before ovulation. The "stem" of the pear is the tract

the follicle develops leading to the ovulation fossa.

• Echogenicity of antrum: In many case

appear in the antrum close to ovulatio

increase in number and echogenicity,

is likely to be anovulatory.

• It is important to be able to recognize

in the management of endometr

examinations, etc. Because mares re

after ovulation, many mares are bred

ovulated. Detecting ovulation will red

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s, hyperechoic particles will

n. However, if these particles

this indicates that the follicle

ovulation. This is a key event

itis, scheduling pregnancy

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uce unnecessary breedings,

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thereby reducing contamination of the uterus and preserving

stallion reserves for mares that need it.

Corpus luteum

• A very recent ovulation may be hard to detect upon examination.

• Within 12 - 24 hrs, it will fill in and have a hyperechoic

appearance.

• The equine CL has great variation in its ultrasonographic

appearance.

• It can have a homogenous echotexture or a trabecular

appearance.

• The appearance often changes somewhat as the CL matures. A

CL may remain visible as a smaller hyperechoic structure even

after luteolysis.

Uterus

• Examination of the uterus is extremely helpful in determining the

stage of the estrous cycle.

o Anestrus: the uterus is thin and elliptical, with a fairly

homogenous echotexture, bright spots indicating air are not

uncommon


o Estrus: a characteristic pattern, giving the appearance of an

orange slice or wagon wheel, results due to the edema in the

endometrial folds

o Diestrus: edema is absent, the uterus is round (more so than

during anestrus), homogenous echotexture of the uterus

Thi

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s is helpful when breeding a mare with shipped semen. For example,

mare is given prostaglandin and is presented for examination based

the time lapse since the prostaglandin injection and the owner's

ression that the mare is coming into estrus, and upon examination

a 43 mm follicle but no edema in the uterus - should semen be

ered? Probably not. It may be that that follicle is going to regress and

will build a new follicle, accompanied by uterine edema, in the next

days.

Estrus Diestrus Anestrus

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Uterine pathology

• The ability to view uterine pathology with ultrasonography is

indispensable in managing the infertile mare.

• Excessive uterine edema and fluid in the lumen during estrus

before breeding, retention of fluid in the uterus after breeding, fluid

in the uterus during diestrus are all examples of pathologic

problems that would go undiagnosed without the benefit of

ultrasound.

• The best way to diagnose this problem is with ultrasonography in

the period after mating.

• Fluid present in the uterus at 12 or 24 hours after breeding is a

clear indication for therapy to improve uterine clearance.


• Endometrial cysts, although their role in infertility is somewhat

controversial, may cause problems in early pregnancy diagnosis

and identification of twins. Small cysts do not interfere with normal

pregnancy.

o During ultrasound examinations before breeding, the

location, size and shape of endometrial cysts should be

recorded.

o Photographic records are ideal.

o In this way, archival information is available which will aid in

future examinations and the ability to discern a vesicle.

Large multilobulated cysts

Normal pregnancy

Endometrial cyst

Normal pregnancy

Endometrial cyst


o Endometritis: fluid present in the uterus has many echogenic

particles inside. The wall is thick and hyper echogenic.

Pregnancy

• Early detection of pregnancy is critical for good broodmare

management.

• Basically, it not only provides information on whether or not the

mare is pregnant but allows one to manage twin pregnancy in the

most advantageous manner, may serve to give early notice of a

uterine infection and if not pregnant allows mare time to arrange re-

breeding.

Blood vessels

Thick uterine wall

Hyper-echogenic fluid

Blood vessels

Thick uterine wall

Hyper-echogenic fluid


Ultrasonic Characteristics of early pregnancy in thoroughbred mares. (A) 15 day pregnancy note the echogenic lines on the dorsal and ventral locations (dorsal and ventral arrows) on the yolk sac； (B) 18 day pregnancy note the Guitar-pick shape of the conceptus; （C）21 day pregnancy note the irregular form of the conceptus and the embryo can be seen as small echogenic dot (white arrow) in the ventro-medial aspect of the conceptual swelling; （D）28 day pregnancy note the development of the allantois (white arrow); （E） 35 day pregnancy note the dorsal position of the embryo (white arrow) and （F）60 day pregnancy, with the fetus recumbent on the ventral uterine floor.

A B C

D E F


• Normal development of the pregnancy can be monitored and it is

advisable for the practitioner to be familiar with the normal

appearance of the conceptus.

Manipulation of twinning in mare using Ultrasonography


* Abortion can be differentiated from normal pregnancy with ease

Normal and abnormal pregnancy 60 days After mating in thoroughbred mares

Normal ultrasonic appearance of the conceptus in 60 days-pregnant mare

Abnormal ultrasonic appearance of the conceptus in 60 days-aborted mare detected ultrasonographicallyduring routine examination


Fetal sexing

• Fetal sexing is becoming more and more in demand.

• Gender determination is based on the location of the genital

tubercle.

o The genital tubercle is the precursor of the penis in the male

or the clitoris in the female.

o 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.

o Before 58 days the tubercle is not distinct enough and has

not migrated sufficiently to make a distinction.

o After 70 days the fetus is hard to reach until it is

approximately 3.5 to 4 months of age.

o As the fetus gets larger, a transabdominal 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.

Assisted Reproduction Techniques

• Ultrasonography has opened up new possibilities for assisted

reproduction in horses.

• Oocyte collection for GIFT and IVF is based on ultrasound guided

transvaginal oocyte aspiration.


• Fetal sexing can be performed at approximately 60-70 d and after

approximately 100 d.

• Twins, if not managed before fixation of the conceptus or formation

of the endometrial cups, can be reduced to a singleton using

transvaginal ultrasound guided aspiration techniques.


a guide for ultrasonographic examination of the mare

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