Bovine pregnancy at 38 days

Keywords: pregnant, cow, amnion, chorion, allantois, bovine, 38 days, pregnancy diagnosis, palpation

A bovine pregnancy of approx 38 days from a Holstein cow that was bred by a bull. The cow died suddenly from a unknown cause.  This tract is shown in another LORI entry in an unopened state.

This image shows early placentome formation with small cotyledons on the fetal side and caruncles of the maternal side. The  outermost membrane of the placenta (the chorion) has been stripped away partially to show the underlying allantois on either side of the amnion. Details of these membrane systems and bovine placentation are discussed and shown in greater detail elsewhere in LORI.

Image size: 1222 x 792px

Interestingly, it was not possible to determine the gender of this fetus with certainty by macroscopic examination of the genital tubercle. Although it was close to the caudal aspect of the umbilical cord indicating that this was probably a male, the base of the tail was also close to the cord, normal for this stage of gestation; not excluding the possibility of a female. Certainly this would not have been possible by transrectal ultrasonography.

General anatomy of the bovine tract

Keywords: bovine, pregnant, tract, cow

This is an illustration of the bovine tract exclusive of its blood supply and mesometrial support. The larger image (2000 x 889 px) below

is supported by this smaller (1148  x 768 px ) keyed image.

Note that these images were obtained by photographing the tracts under water with 5000K LED lighting. This method of suspension reveals structures that are not normally visible with when the tract is held in an air environment. See below (pending). Also, the wavelength of the light used demonstrates colors not usually visible in ambient light. No processing manipulation of colors has been used. For example, the bright pink color of the uterine tube (fallopian tube) is its natural appearance under these conditions.

A pregnant bovine uterus with leucosis

Keywords: leucosis, uterus, bovine, cow, pregnant, BLV

A uterus was examined from a six year old Holstein cow after two lactations; pregnant for a third time. The cow had been losing weight, her milk production had diminished unexpectedly and she had begun to show ataxia. Not being a valuable asset to the herd, she was culled and submitted for postmortem examination.

The cow had been bred 54 days before the date of culling. Interestingly, a highly experienced bovine practitioner had palpated her uterus transrectally shortly before breeding and found it to be apparently normal. Yet, approximately 60 days later, the same practitioner reported that uterus was both rigid and thick-walled. As shown below, ultrasonography revealed a grossly thickened uterine wall and a live fetus with a normal heart rate (~ 190bpm).

(Ultrasonographic image copyright: Dr B. Crane. AVC)

Image size: 574 x 435px

This finding suggested that the neoplastic process had developed very rapidly; a common finding in leucosis.

Based on histopathology, lymphomatous masses were present in numerous locations including internal lymph nodes, kidneys, the right atrium, the abomasum and in the spinal epidural space. The subdural lesions probably accounted for ataxia exhibited by the cow. Findings in the uterus are shown below.

Image size: 1189 x 1000px

There was diffuse but variable thickening of the myometrium with lymphomas, creating a friable uterine wall that developed fissure lines where it was manipulated. There were also several lymphoma nodules in the vagina. Surprisingly, the 54 day old fetus and its membranes were not autolysed, indicating that the fetus had probably survived until the time of euthanasia of the dam. 

Notes: There are several forms of lymphosarcoma in cattle but only one form has a known etiology i.e. bovine leucosis, caused by the bovine leucosis retrovirus (BLV). Bovine leucosis is not considered to be a common cause of abortion, probably because so few animals that are carrying BLV actually become symptomatic. However, as is evident from this case, leucosis does have the potential to cause abortion in cattle. 

Transfer of BLV is usually vertical and must occur by cell transfer, therefore events such as calving, surgical intervention, dehorning and even transrectal palpation have been incriminated. However, recent data has shown that transrectal palpation may not be as significant in the transmission of leucosis as once believed.

No vaccine is available for the control of bovine leucosis so control is often exercised by culling of test-positive animals. Fortunately, BLV is not transmitted during embryo transfer. Therefore embryos from BLV positive cows can safely be transferred to BLV negative surrogate heifers.

Quadruplet bovine pregnancy

Keywords: quadruplets, bovine, cow, pregnancy, placenta, allantois, allantochorion

Image size: 1000 x 807px

Old images (~1975) of bovine quadruplets at about 35 days of gestation. This was found in a slaughter specimen where the cervix had been traumatized (and was in a state of healing) and multiple corpora lutea were present in both ovaries. Presumably an attempt had been made to super-ovulate this cow and collect embryos earlier in gestation. Therefore it is unlikely that this pregnancy was the result of spontaneous multiple ovulations. Spontaneous triplets occur in about 1 in 10,000 calvings but quadruplets are so rare that their incidence cannot be accurately reported. Reports suggest that they may occur in about one in a half million calvings.

This specimen was interesting from a two of points of view. First, despite fetal overcrowding, the uterus was able to sustain a quadruplet pregnancy to this stage and second, the fact that the chorions of all four pregnancies had fused yet differential staining of each fetus (methylene blue, clear, dark iodine and light iodine) showed that the allantois of each fetus remained separate. This is shown below.

Image size: 1000 x 806px

Holstein triplets

Keywords: triplets, bovine, cow, pregnancy,hymen

Image size: 2816 x 2112px

Triplets from a six-year-old Holstein cow weighing 652 Kg at the time of admission. The cow died at the time of admission due to fatty infiltration of the liver. It was assumed that the cow had been in a state of energy deficiency because she was carrying triplets.

These triplets were conceived during a nonmedicated cycle but the cow had produced twins earlier in her life and was a cotwin herself. There were four corpora lutea in her ovaries.

Image size: 2668 x 1298px

Interestingly, in addition to the triplets an amorphous globosis (shown in the top image between the calves) was present, suggesting that it had been conceived from the fourth ovulation. If this had indeed been the case, it probably did not have a male genotype because the three calves were apparently normal, showing no signs of freemartinism.

Image size: 2816 x 2112px

The only abnormality in the genital tract of one calf was the presence of a partially persistent hymen. That hymen is shown by the lower probe on the right side of this image. The upper probe merely illustrates that this calf had a normal cervix.

Approximately one month before they would have been born, the weight of the calves and their crown-rump measurements (respectively) were as follows: 26Kg 84cm, 22Kg 78cm and 28Kg 87cm.

Note: Predisposition to twin ovulation is heritable and varies accordingly from ~ 0 to 15%. Presumably, there is a predisposition to multiple ovulations in general. In beef, triplets births account for less than 0.01% of all calvings. Figures for dairy cows are probably similar.

Interestingly, in super ovulated cattle it has been shown that up to 3 fetuses may be present within within a single uterine horn with up to five calves going to term. When third calves were cross-fostered to a dam whose calf had died, survival rates to weaning were 96%, 86% and 69% for singlets, twins and triplets respectively (Echternkamp J. 1992, Anim. Sci. 2007. 85:3239-3248)

Synchronizing follicle growth in cattle; Ovsynch

Keywords: synchronize, bovine, ovsync, cow, estrous, estrus, cycle, mechanism

Image size: 5363 x 6393px

This diagram, extrapolated from many sources, shows the mechanism of Ovsynch treatment.

The receptive periods during the estrous cycle when GnRH will cause ovulation  are shown as gray vertical bars. If GnRH is given during any of these periods (about 65% of the duration of a three wave estrous cycle) follicles present at that time will ovulate, causing a drop in inhibin, FSH release, and the start of new wave of follicle growth. It is this wave of of follicle growth that is utilized to provide synchronous ovulations about nine days later.

As mentioned, a synchronous response to the first injection of GnRH occurs in about 65% of cows. Nine days after the first injection of GnRH, some of the non-responding cows will either respond to the injection of prostaglandin and show estrus or they may show estrus spontaneously. In this manner, about 65% of cows will respond to the first injection of GnRH and about 35% of the cows (the non-responders) will be in estrus after the injection of prostaglandin and will respond to to the second injection of GnRH, together with the other cows. Collectively this means that about 85% of all the treated cows could respond to Ovsynch treatment.

These figures assume that all the cattle being treated are actually having estrous cycles. In high producing cows, is seldom the case so the response to Ovsynch treatments may often fall short of these calculations.

Synchronizing follicle growth in cattle.1

Keywords: synchronize, bovine, ovsync, cow

Image size: 5370 x 3534px

This diagram, extrapolated from many sources, shows the receptive periods during the estrous cycle when GnRH will cause ovulation (gray vertical bars). If GnRH is given during any of these periods, follicles present at that time will ovulate, causing a drop in inhibin, FSH release, and the start of new wave of follicle growth. It is this wave of of follicle growth that is utilized to provide synchronous ovulations about nine days later.

Seven days after the initial injection of GnRH, an injection of prostaglandin is given to cause luteolysis of the corpora lutea that were formed seven days earlier. Two days after the injection of prostaglandin, another injection of GnRH is given so that the follicles that have grown in the new wave are induced to ovulate. Sometimes cattle are bred at this time; this is called "Cosync" treatment because the second injection and the time the breeding coincide. Alternatively, they can be bred at a fixed time, usually about the morning after the second injection of GnRH (about 16 hours later). This is referred to as "Ovsync" because ovulations are closely grouped around this period of time. Finally, cows may only be selected for breeding if they show heat; hence the name "Selectsync".

In some instances, injections of prostaglandin are given (even if "Ovsync" itself may be used) to increase the chances that cows will be in the receptive periods (gray vertical bars) at the time the first GnRH is given for Ovsync. The economic value of these pre-synchronization ("Presync") treatments is questionable.

Normal lochia from a dairy cow

Keywords: lochia, postpartum, bovine, cow, involution, uterus

Image size: 1200 x 1600px

Normal lochia from a dairy cow at 12 days postpartum; seen in its bedding. At this time, the sloughing process of the caruncles reaches the capillary beds, releasing red blood cells into the lumen. Therefore this discharge is normal and in the absence of fever, inappetence and other common pathology at calving (mastitis, traumatic reticulo-pericarditis etc) it requires no treatment.

Sensitive periods for Ovsynch treatment

Keywords: cow, synchronize, bovine, estrous, estrus, cycle, follicle, wave, Ovsynch

A diagram modified from several sources, showing an estrous cycle with three follicle waves. The physiology of two or three follicle waves is important during “Ovsych” treatment (GnRH-Prostaglandin-GnRH) because it is only those follicles that have already been recruited and already growing in a follicle wave that will ovulate after GnRH treatment; an essential step in re-setting the recruitment of follicles so that a mature follicle will be available for ovulation about 8 to 9 days later. This image shows the periods of time (vertical grey bars) during which follicles can be induced to ovulate by GnRH treatment.

Postpartum corpus luteum in a cow

Keywords: cow, bovine, postpartum, ovary, corpus luteum, CL

Image size: 1044 x 778px

Corpora lutea (CLs) in the ovary of a cow approximately one week after she had given birth to twins. The cow was euthanized because she had injured herself during calving. This image shows that corpora lutea are still present within the ovary for at least a week after calving; this despite the fact that they are not required for the maintenance of pregnancy for the last four months of gestation. These corpora lutea would have been producing little if any progesterone. In fact, cows can be ovariectomized after the first month of gestation and will maintain pregnancy and can calve normally. Therefore, the role of the ovaries (and corpora lutea in this case) during late gestation cattle is uncertain.

The cervix of a postpartum cow

Keywords: cervix, involution, bovine, cow, endometrium, lochia

Image size: 868 x 707px

The cervix of a cow seen at approximately one week after calving. This animal was euthanized because of a skeletal injury sustained during the birth of twin calves. Minor contusion and lacerations such as those seen here are common after parturition.

The bovine cervix closes down fairly rapidly after calving so that at this time (about a week after calving) it is difficult to introduce a hand into the uterus. However, the cervix remains open for at least 20 days to allow the discharge of lochia. This lochia becomes hemorrhagic at about 10 to 12 days when the remnants of the caruncles of pregnancy are sloughed to the level of the endometrial capilliary beds. It is also at about this time that the lochia begin to become purulent in nature as neutrophils enter the lumen from the capilliary beds. Therefore, if this photograph had been taken a few days later, it would not be unusual to find a hemorrhagic and somewhat purulent discharge being voided through the cervix.

Follicle and a corpus luteum; ultrasound

Key words: wave, bovine, CL, corpus luteum, follicle, cow, ultrasound

Image size: 640 x 480px

A large follicle (the anechoic structure) adjacent to a corpus luteum (CL) in the ovary of a cow; as seen during transrectal ultrasonography. Follicles grow and regress in waves during the bovine estrous cycle. There are commonly two or three waves of follicle growth during the diestrous period. When there are three waves, the estrous cycle is longer (21 to 22 days) than when they are two follicle waves (19 to 20 days). Less commonly,  cows may even have four follicle waves. Therefore the discovery of a large follicle during diestrus (as in this case) does not necessarily mean that a cow is approaching estrus.

A follicle and a luteinized cystic follicle

Keywords: CL,corpus, luteum, cystic, bovine, cycle, infertility, cow, ultrasound

Image size: 640 x 480px

A follicle and a luteinized cystic follicle seen by transrectal ultrasonography in a cow.

Together with its appearance, a history of postpartum anestrous allowed a diagnosis of a luteinized cystic follicle (sometimes referred to a luteal cyst) in this cow.  Cystic follicles and the luteinized structures they develop into, are abnormal structures, associated with an absence of estrous cycles in the early to late postpartum period; almost always in dairy cows. In dairy cows, abnormal estrogen secretion and abnormal LH surges are thought to be important in the syndrome. Cystic follicles are also seen in beef heifers, but usually only after the use of steroid growth promoters.

Clarification: Cystic corpora lutea are normal structures, associated with normal estrous cycles.  Most corpora lutea luteinize completely, obliterating the antrum of the ovulated follicle but many are left with small to large cysts in the center.  This author does not use the term “luteal cyst” (an abnormal structure) because it can easily be confused with the term “cystic corpus luteum” (a normal structure). Instead, the term luteinized cyst (a cystic follicle that has become luteinized) should be used.

Bovine leucosis in a pregnant uterus

Keywords: BLV, cow, bovine, leucosis, pregnant, vagina

Image size: 1672 x 1404px

Enzootic bovine leucosis is a result of infection by bovine leukemia virus (BLV). Less than 1% of all the cattle infected with this virus actually develop lymphoid sarcomas and often these are found in pregnant cows. In this case, where the cow was approximately 5 months pregnant, the vagina was affected (black arrows) as well as the myometrium (yellow and green arrows). The double ended green arrow shows a diffuse area of the myometrium thickened by a sarcoma.

Bovine mucometra/hydrometra

Keywords: adhesions, bovine, hydrometra, mucometra

Bilateral peri-uterine adhesions and fibrosis of the perimetrium/myometrium which appear to have caused distortion and mucometra.

Image size: 1023 X 1283 px

Dissection of the tract did not reveal a specific area of occlusion that would have resulted in this condition. It is possible that the inciting cause was fibrosis of the cervix itself. 

This condition should be referred to as mucometra because it is characterized by an accumulation of mucus; not water (hydro). It is not related to a chromosomal abnormality such as that in polled intersex goats i.e. the PIS syndrome. It is a rare condition in cattle, manifested by unilateral or bilateral distension of the uterus with clear fluid. Occasionally the fluid may contain clumps of inspissated tissue the nature of which have not been described.  In studies on slaughter plant specimens, mucometra occurred in about 0.1 to 0.8 percent of cattle.

Mucometra occurs in cattle as a result of adhesions or fibrosis (as seen here). It is also seen in cattle with segmental aplasia or in heifers with persistent hymens. Mucometra has also been linked to chronic cystic ovarian disease (COD) but is by no means, characteristic of that condition.

References:

Fathalla, M. et al 2000 An  abbatoir survey of gross reproductive abnormalities in the bovine genital tract in northern Jordan. Israel. J. Vet. Med. 55. No page numbers. Available on-line.

Roberts, S. J.1986. Veterinary obstetrics and genital diseases (Theriogenology). Published by the author.  ISBN-10: 9997670922. ISBN-13: 978-9997670922

Lymphosarcoma pyometra in a cow

Keywords: lymphosarcoma, pyometra, cow, unusual, BLV, leucosis, bovine, uterus, pus

Image size: 1182 x 1756px

An unusual form of pyometra in a cow. Usually, pyometra in cows is due to infection with Arcanobacter pyogenes during the postpartum period. In this case, pyometra was due to bovine leukosis caused by the bovine leukemia virus (BLV). Usually, cows with leucosis in the uterus have multiple nodular disseminated foci of lymphosarcoma; occasionally, large plaques of lymphosarcoma in the myometrium. In this case, there were no typical modules of lymphosarcoma in the uterus. Instead there was a large volume of pus in the uterus, composed entirely of lymphocytes. As is usual, the cow also had disseminated leucosis nodules throughout many of its organs; the spinal canal, heart, liver etc.

Pyometra or following insemination

Keywords: Tanabe, bovine, cow, insemination, pyometra, Arcanobacter pyogenes

Pyometra that followed insemination in a cow. Pyometra usually occurs spontaneously in postpartum cows as a result of infection with Arcanobacter pyogenes. This image is regarded as unique because it states that in this case the pyometra occurred after insemination, suggesting iatrogenic contamination as a cause the condition.

An update has kindly been provided by Dr R.G. (Dick) Saacke, Professor Emeritus of Reproductive Physiology. Dept. of Dairy Science, Virginia Polytech. Inst. and State University (edited):

This image was produced by Dr. TY Tanabe at Penn State University. The image was taken after a pregnant cow was bred trans-cervically during early pregnancy. At the time, liquid semen without antibiotics was used. This resulted in the loss of pregnancy and in some cases, pyometra as seen here. As a consequence of his research, Dr Tanabe recommended that if a cow should show heat after being bred, the subsequent insemination should be no deeper than mid-cervix. He produced many images addressing the disastrous consequence of insemination at several stages of pregnancy

Dr. Tanabe has since died, but many of his excellent photographs are digitized and available through the USDA Image library. 

Author's note: Insemination of pregnant cows still occurs but it is remarkable that many of these pregnancies survive. This is either due to the addition of antibiotics or caution of technicians sensing the possibility of pregnancy, inseminating intra-cervically.

Adventitious placentation in a cow. 

Keywords: placenta, adventitious, placentitis, bovine, cow, infertility

Small to large irregular placentome-like structures may develop on the placenta adjacent to normal placentomes. These have been referred to as "adventitious" placentomes and the condition itself as "adventitious placentation". The word adventitious is derived from the Latin meaning "coming from outside" but in zoology, it refers to something that is in an unusual position or place. The adventitious placentomes may be localized or spread throughout the allantochorion/endometrium.

It is often stated that adventitious placentation is associated with hydrops conditions but it may occur in seemingly normal pregnancies. However, when adventitious placentation is obvious, one should probably consider the placenta and uterus as a unit and cull the cow because of the potential for infertility.

Luteinized follicles. COD in a cow.

Keywords: COD, cystic, ovarian, ovary, luteinization, disease, cow, production, bovine

Several follicles in one ovary show various degrees of luteinization after chronic low-grade LH stimulation. The presence of numerous follicles indicate that there was no deficiency of FSH in this cow. As is usually the case for cows with cystic ovarian disease (COD) this cow would probably not have shown estrus for a prolonged period of time.

It was once believed that these cows would not ovulate while cystic structures such as these persisted in their ovaries. However it has since been shown that estrous cycles may resume with ovulations adjacent to these cystic structures.

COD in dairy cows is usually associated with high levels of milk production; in beef cows is associated with the use of steroid containing growth promoters.

The bovine estrous cycle

Keywords: estrus, estrous, progesterone, prostaglandin, estradiol, LH, FSH, bovine, cow

Note: The use of estrus as an adjective is less common than estrous (1.23 million vs 840 thousand Google hits respectively). Nevertheless, estrus is often used as an adjective e.g estrus cycle, estrus behavior, estrus synchronization etc. Indeed, it has become so common as to be regarded as both a noun and an adjective. However, the author adopts the more common term estrous as an adjective in this entry. In the British commonwealth, the terms oestrus and oestrous are used for the noun and adjective respectively.

The image shown here is useful for explaining the bovine estrous cycle*. It shows the rise of estradiol 17 beta that brings the cow into heat and causes a surge of luteinizing hormone (LH). Ovulation usually occurs about 16 to 24 hours after the onset of the LH surge i.e. when the cow is no longer showing signs of estrus.

After ovulation has occurred, a corpus luteum forms from the structure that was previously the follicle, producing progesterone (the yellow profile)  for approximately 19 days. If the cow is not pregnant, at about 15 to 16 days after ovulation, the endometrium releases prostaglandin F2 alpha (PG) which causes luteolysis i.e. the demise on the corpus luteum. Immediately after ovulation has occurred a new wave of follicle growth begins because inhibin production by the previous large follicle, is no longer present. This results in an elevation of follicle stimulating hormone (FSH).

A dominant follicle is selected in each follicle wave, suppressing its cohorts. If that follicle does not ovulate, it undergoes regression and a new follicle wave begins. There are usually three such follicle waves during each estrous cycle but in young animals, there may be only two waves, resulting in an interovulatory interval that is a few days shorter than a conventional estrous cycle of  21 or 22 days.

Standing estrus last for about 8 to 12 hours in most dairy cows but may be much shorter (and difficult to detect) in high producing cows. Very short estrous periods are typical of zebu-type cattle as well.

*Readers are strongly encouraged to consult an excellent resource on the bovine estrus cycle developed by Dr Roberto Palomares, Kip Carter and colleagues at The College of Veterinary Medicine, University of Georgia. The presentation is available for Mac or PC use.

The Mac OS version has full animation. Lacking some animations, the PC (epub) version however remains valuable for all students of reproductive physiology. On most PC computers, the ePub version can be viewed without downloading ePub readers.