Pregnancy and it's Detection in the Cow

[Kvet Forum]

𝙈𝙚𝙩𝙝𝙤𝙙𝙨 𝙤𝙛 𝙥𝙧𝙚𝙜𝙣𝙖𝙣𝙘𝙮 𝙙𝙞𝙖𝙜𝙣𝙤𝙨𝙞𝙨

A variety of different methods have been, and are still, used to detect the presence or absence of pregnancy in the cow. These range from the identification of substances that are present in body fluids using laboratory assays, and from different ultrasound modes, to simple clinical methods such as transrectal palpation; the latter has been the most widely used method for the last 70 years.

In terms of efficient livestock production, it is the early identification of the non-pregnant cow that is important, since immediate measures can be taken to attempt to induce pregnancy again as soon as possible.

Clinical methods for Pregnancy Diagnosis - Trans-rectal palpation.


1. 𝙋𝙖𝙡𝙥𝙖𝙩𝙞𝙤𝙣 𝙤𝙛 𝙩𝙝𝙚 𝙖𝙢𝙣𝙞𝙤𝙩𝙞𝙘 𝙫𝙚𝙨𝙞𝙘𝙡𝙚

This method involves the palpation of the amnion towards the end of the first month of pregnancy. It proceeds briefly as follows.
The bifurcation of the uterine horns is located, then the horns are uncoiled and gently palpated along their entire length between the thumb and middle two fingers. The amniotic sac can be felt as a distinct, round, turgid object 1–2 cm in diameter floating in the allantoic fluid. The vesicle should not be compressed directly but gently pushed backwards and forwards. Some consider that this technique is dangerous because of the possibility of rupture of the amniotic sac or of the embryonic heart. As with all rectal techniques care is the rule, and excessive pressure and rough handling should be avoided.


2. 𝙋𝙖𝙡𝙥𝙖𝙩𝙞𝙤𝙣 𝙤𝙛 𝙩𝙝𝙚 𝙖𝙡𝙡𝙖𝙣𝙩𝙤-𝙘𝙝𝙤𝙧𝙞𝙤𝙣 (𝙢𝙚𝙢𝙗𝙧𝙖𝙣𝙚 𝙨𝙡𝙞𝙥).

This method is dependent upon the facts that in the cow, attachment of the allanto- chorion to the endometrium occurs only between the cotyledons and the caruncles, and that the inter-cotyledonary part of the fetal membrane is free. The method was first described by Abelein (1928), who reported that it could be used from the fifth week of gestation. The method is as follows.
Identify the bifurcation of the uterine horns, pick up the enlarged, gravid horn between thumb and either index or middle finger just cranial to the bifurcation and gently squeeze and roll the whole thickness of the horn. The allantochorion will eventually be identified as a very fine structure as it slips between the thumb and finger before the uterine and rectal walls are lost from the grasp. It is important in the early stages of pregnancy to grasp the whole width of the horn because as the allantochorion is very thin at this stage the structure that can be more readily identified is the connective tissue band which contains the blood vessels supplying the allantochorion.
Fincher (1943) recommended that it should not be used before 40 days of gestation and that it was infallible up to 95 days. The advantage of the method is that it enables the differential diagnosis of pregnancy from mucometra or pyometra. In some cases, particularly after 60 days of gestation, it can be more readily elicited in the non-gravid horn since the tension on the wall is less and this allows it to be grasped more readily. For the beginner it is a worthwhile exercise to practice it on a fresh gravid genital tract from the abattoir.


3. 𝙐𝙣𝙞𝙡𝙖𝙩𝙚𝙧𝙖𝙡 𝙘𝙤𝙧𝙣𝙪𝙖𝙡 𝙚𝙣𝙡𝙖𝙧𝙜𝙚𝙢𝙚𝙣𝙩

Unless there are twin conceptuses, one in each horn, it is possible to detect a difference in the size of the two horns. This is largely due to the presence of fetal fluids, in particular allantoic fluid, which gives the uterine horn a fluctuating feel with good tone. It can be likened to the feel of a toy balloon which has been filled with water to a point when the wall just starts to stretch. At the same time, if the wall of the horn is squeezed it is noticeable that it is much thinner than that of a non-gravid tract. In many cases a definite diagnosis of pregnancy can be made on these signs alone.
The presence of a corpus luteum in the ovary adjacent to the enlarged horn is a useful confirmatory sign; however, a false diagnosis of pregnancy may be made in cases of pyometra, mucometra or incomplete uterine involution.


4. 𝙋𝙖𝙡𝙥𝙖𝙩𝙞𝙤𝙣 𝙤𝙛 𝙩𝙝𝙚 𝙚𝙖𝙧𝙡𝙮 𝙛𝙚𝙩𝙪𝙨

At about 45–50 days of gestation the amniotic sac becomes less turgid, and it is sometimes possible to palpate directly the small developing fetus. This should be done with care.


5. 𝙋𝙖𝙡𝙥𝙖𝙩𝙞𝙤𝙣 𝙤𝙛 𝙘𝙖𝙧𝙪𝙣𝙘𝙡𝙚𝙨/𝙘𝙤𝙩𝙮𝙡𝙚𝙙𝙤𝙣𝙨

Caruncles/ cotyledons first become recognizable by rectal palpation at 10–11 weeks as roughened elevations when the fingers are passed back and forth over the surface of the enlarged gravid horn. From about 3 months they can be identified as discrete structures in the midline, about 8–10 cm in front of and over the pelvic brim, by pressing down upon the uterine body and base of the horns.
In the early stages it is difficult to identify them as distinct, individual structures. The uterus feels as if it has an irregular corrugated surface; it has been likened to palpating a sackful of small potatoes. As pregnancy proceeds, the cotyledons become larger, but once the uterus has sunk into the abdomen between 5 and 7 months, it is sometimes impossible to palpate them, although if loosubstantial pressure is placed on the body of the uterus just cranial to the cervix with the flat portion of the fingertips, as if attempting to palpate the udder transrectally. Identification of cotyledons is virtually diagnostic of pregnancy, but in the immediate postpartum uterus they can also be felt.


6. 𝙋𝙖𝙡𝙥𝙖𝙩𝙞𝙤𝙣 𝙤𝙛 𝙩𝙝𝙚 𝙘𝙚𝙧𝙫𝙞𝙭

Evidence of pregnancy can be assumed when there is tension on the cervix. In the non-pregnant or early pregnant cow or heifer the cervix is freely movable from side to side. However, as pregnancy advances the cervix becomes less mobile and it is pulled forwards and downwards over the pelvic brim.


7. 𝙃𝙮𝙥𝙚𝙧𝙩𝙧𝙤𝙥𝙝𝙮 𝙤𝙛 𝙩𝙝𝙚 𝙢𝙞𝙙𝙙𝙡𝙚 𝙪𝙩𝙚𝙧𝙞𝙣𝙚 𝙖𝙧𝙩𝙚𝙧𝙮 𝙖𝙣𝙙 𝙙𝙚𝙫𝙚𝙡𝙤𝙥𝙢𝙚𝙣𝙩 𝙤𝙛 𝙛𝙧𝙚𝙢𝙞𝙩𝙪𝙨.

In a non-gravid or early pregnant cow, identification of the middle uterine artery by palpation is usually not possible transrectally. The artery runs in the broad ligament, along a tortuous course, passing downwards, forwards and towards the midline over the pelvic brim close to the junction between pubis and ilium.
Usually, it is identified 5–10 cm lateral to the cervix. Inexperienced persons sometimes confuse it with the iliac and obturator arteries, but the middle uterine artery is mobile and it can be encircled within the thumb and forefinger.
At some stage during pregnancy it will cease to have the usual pulse, and instead it will become a ‘thrill’ or tremor, which is called fremitus. There is considerable variation in the time at which the change can first be felt and also when it becomes continuous. The earliest the author has been able to detect it is at 86 days. During the period 100–175 days cases will frequently be met which ‘thrill’ at first but later pulsate. It is probable that the degree of pressure applied to the artery influences the feeling imparted to the fingers; light pressure detects a ‘thrill’, whereas a pulse wave is apparent to heavy pressure. The ‘thrill’ generally becomes continuous after day 175, although cases will be met in which there is distinct pulsation as late as day 200. During the terminal stages of gestation the uterine arteries become greatly hypertrophied and tortuous; they can be distinctly felt, with the thickness of a pencil, with a continuous, tremor-like pulse, laterally situated 2 cm or so in front of the cranial border of the iliac shaft. A difference in size of the two uterine arteries is usually recognisable from about day 100, and this indicates the side of the pregnant horn. Palpation of the middle uterine artery is usually possible in even the biggest cow, and thus is particularly useful in large beef suckler cows.
Fremitus in the posterior uterine arteries was detected between 200 and 248 days on the gravid side and between 235 and 279 days on the non-gravid side by Tsolov (1978). He also found that the onset of fremitus was later, the greater the number of times the cow had been pregnant.


8. 𝙋𝙖𝙡𝙥𝙖𝙩𝙞𝙤𝙣 𝙤𝙛 𝙩𝙝𝙚 𝙡𝙖𝙩𝙚 𝙛𝙚𝙩𝙪𝙨.

Palpation of the fetus, either per rectum or by abdominal ballottement, is diagnostic of pregnancy. The ease of palpation depends upon the size of the cow, the degree of stretching of the suspension of the uterus, and the degree of relaxation of the rectum and uterine wall.