---start--- repro 10.14.98 1. nonpregnant cow (first two hours) 2. pregnant cow (second two hours) 3. postpartum cow (last two hours) The Nonpregnant Cow slide: udder of a cow (uber vaccae) some terminology for the cow-deprived among us: heifer: female bovid who has not yet had a calf - recognized by size - not fully grown yet - and size of udder will be small. especially in dairy cattle, heifer udder size is obviously small. first calf heifer: female bovid who has had one calf. sometimes called a cow. cow: female bovid who has had one or more calves; large udder is present; full grown, mature animal. fresh cow: not a cow with baby powder, soap, just out of shower; but a cow who has recently had a calf to freshen: to calve to clean a cow: to help her pass her fetal membranes; not really something you can do, although farmer will ask you to. to clean: to pass the fetal membranes service: to breed first service: first breeding Anatomy: basic review - bovine ovaries are smaller than mare ovaries. without a corpus luteum, about the size of a large lima bean. follicles on bovine ovaries are small - preovulatory follicle is about 10-15 mm. In mare, 35-40 mm, so that's a big difference. but in the cow,they are small. corpora lutea - an active CL will double the size of and distort the shape of the ovary. the crown of it is visible from the surface, the body extends down into the ovary. the CL is palpable per rectum and easily distinguished. not all have crowns, but even if they don't you can palpate the CL. this is one of the more definitive structures on the ovary. different from the mare - usually in mare, CL is internal and nonpalpable. CL can also be fluid filled - that's a cystic CL - you can't palpate that but you see it on US. cystic CL is normal in cow. different from luteal cyst, which is a pathologic structure which interferes with cyclicity. most bovine CLs are somewhat cystic. trivia: studies have shown a statistic significance to the fact that most ovulations occur from the right ovary of cow. cows have no ovulation fossa, either - ovulation occurs from any surface of ovary Oviduct: infundibulum - the fimbriated basket that catches the ovulated oocyte; ampulla - site of fertilization; isthmus - narrow part connecting ampulla to uterus, this is where sperm get stored, they attach to epi cells there and hang out until egg enters ampulla. in the cow, there is no sphincter b/w the isthmus and uterus, so bacteria can get into the oviduct unlike in the horse, so pyosalpinx is more common in cow than the mare. it's hard to palpate a normal oviduct per rectum, though you can sometimes feel them like little strings. if pathologic, you can uualy feel them. slide: huge, inflamed oviduct almost as big as the uterine horn! pyosalpinx. this is not good. inflammation like this would cause adhesions and render the oviduct nonpatent. if this happens on just one side, cow could still get pregnant if she ovulates off other ovary. but if she ovulates on the ipsilateral ovary, she won't get pregnant. so conception rates would go down about 50%. severe bilateral salpingitis carries poor fertility prognosis for pregnancy by normal means. can also see adhesions from oviduct to ovary or to uterus. usually salpingitis is due to ascending infxn from uterus. ldie: more adhesions - whole oviduct is sort of wrapped in thickened fibrous tissue connecting it to ovary and uterine horn. this impairs fertility. uterus of cow is interesting - short uterine body, two long uterine horns that are joined through about 2/3 of their length by intercornual ligament. often it feels like the uterine body is larger than it is, b/c of that ligament, but if you palpate carefully you can feel the bifurcation of the horns. if you pass a pipette in there, you don't want to poke into the bifurcation area. you can traumatize it, cause granulomas or something. in nonpregnant cow, uterus lays on floor of pelvis, but in pregnant or fresh cow, it falls forward and a lot of it can hang down into the abdomen. it's freely movable - you can pick it up and move it, per rectum. cows do not seem to mind. so it is sometime harder to find, too. mare uterus isn't movable like that. uterine tone changes with stage of estrus cycle. if it's very tightly coiled, and has high tone, she has high estrogen levels - is in heat, estrus. in diestrus, more flaccid, less tone, more droopy, less coiling. diameter of horns also varies a lot depending on if she's had calves. once she's calved, horns are asymmetric. that's normal. another thing is the caruncles - the maternal half of the placental units - are always present on endometrium, even in heifers. you can see little white raised areas if you look in there. they change a lot in size in pregnant cows. if you do not see the caruncles on postmortem, that's a pathologic change - endometrium sloughed, or fibrosed, or something. pathology of uterus - very common. anyone who does any bovine practice will see uterine infections in postpartum cows. retained fetal membranes - cows that do not clean fast enough - membranes drag in manure, bacteria are wicked up, it's nasty. big problem we'll discuss in postpartum cow. abscesses - slide: big red mass in uterus - someone pushed a pipette into the uterine bifurcation. also tumors - LSA - uterus is a hot site for LSA in cow - this horn is thicker than it should be - napkin ring appearance on cut surface, thickened wall. can palpate this. fluid in uterus - hydrometra; mucometra; pyometra: all pretty common follicular cyst on ovary causes uterine atony and hydrometra - gets full of fluid, or mucometra, full of mucus. if she has persistent hymen, may get hydrometra or mucometra b/c it can't drain. remember, fluid in the uterus isn't always diagnostic of pregnancy - could be pathology. cervix of cow: is very firm, quite long; has fibrous rings, circular fibrous rings that make it easy to palpate - feels like a wide chicken neck, or something. very well defined. never changes the way it does in the mare. in cow, uterine tone is what changes with cycle. in mare, cervix changes a lot. not in cow. ths is b/c of fibrous rings. most of the bos taurus breeds have 3-5 rings, the bos indicus breeds have a lot more, so they have bigger cervices. pathology of cervix - also pretty common. cervicitis - inflammation of cervix - due to pus coming out of uterus, passing of AI pipette, ascending infection from vulva; generally feels larger, thicker, usually resolves w/o tx. can also see cervical ring prolapse - one ring sort of telescopes out - you see the rings telescoping if you look in there. cervix feels thicker per rectum. this is common in multiparous cows, doesn't usually impair fertility or require tx. congenital cervical defects are fairly common - double cervix shown on slide. significance depends on how complete the defect is. remember paramesanephric ducts fuse to make uterus - unfused part is horns, fused part is body/cervix. incomplete fusion creates doubling. complete failure of fusion results in two totally separate uteruses. if she ovulates on one side, and you AI her through the other cervix - won't get pregnant. but if she has two cervices, and only one uterine body, it's not going to matter which side you AI through. but when she calves, if one foot comes through each cervix, you get dystocia. some of thesse defects are thought to be heritable. this is a form of segmental aplasia. some people ssay not to breed any of these cows. cervical tears/defects - slide shows us white, fibrous sheet that is a tear in cervix. small tears are ok, larger ones lead to infertility. surgical repair is rarely possible in cows. vagina, vestibule, vulva: defects of vulvar conformation less common in cow than mare - slide here shows cow with bad conformation - vulva way caudal to anus - manure would go right into vulva. can do caslicks to help her out. can also have imperforate hymens at vestibulovaginal junction - these are just manually torn or cut with scissors. in vagina can see vaginitis secondary to metritis or retained membranes or anything. hyperemic vaginal wall is seen. tx underlying cause and it will resolve. urovagina less common in cow than mare. urine pooling usually is treated surgicaly if it does occur. vaginal cysts - uncommon - cystic vestibular glands or bartholin's glands you will sometimes see. these are just inside vulvar lips - single, paired secretory glands that may become cystic. if they aren't cystic, you don't see them grossly. but if cystic can pouch out vulva and mimic parturition. cystic tubular structures- gartner's ducts- running in wall of vagina. relatively common, remnants of mesanephric duct sytem that haven't regressed. if really full and distended, can protrude through vulva and cconfuse people -they think she's calving. can just lance these glands. less common for these to stick out the vulva than the vestibular cysts. two guys walk into a bar - which is funny, since they should have seen it coming. horse walks into a bar and the bartender says "why the long face?" Puberty: age of onset 6-18 mos in heifer. this is age of onset of cyclicity and it is hoped cow will reach puberty as early as possible to get big profit for the farmer. age of onset is influenced by many things. breed - bos taurus: earlier puberty than bos indicus breeds nutrition - good nutrition promotes onset date of birth - autumn birth = earlier onset than spring birth disease - delays onset what happens at puberty? in prepubertal animal, hypothalamus is very sensitive to inhibitory effects of ovarian steroids. gonadal secretions at very low levels keep hypothalamus secreting really low levels of GnRH/LHRH. this acts on pituitary and makes it rleease LH and FSH - at also very low levels. so there is no follicular development or ovulation. so everything is functioning, at very low levels, tightly regulated. at onset of puberty, hypothalamus gets less sensitive to inhibitory effects - makes MORE GnRH, so pituitary makes more LH and FSH - follicles start to grow, then regress, grow, then regress, uterus gets bigger, secondary sex characteristics appear. finally, hypothalamus is set to new, lower sensitivity - more GnRH still, large amts of LH and FSH, inducing ovulation. now gonad is making way more steroids, so even though hypothalamus is less sensitive, this still work. it'ss a resetting of hypothalamic sensitivity to gonadal steroids that happens in puberty. where do minute steaks come from? two dimensional cows... Once you get first ovulatory follicle, you see high levels of gonadal steroids...first estrus is usually silent - heifer doesn't show heat behavior, so you don't detect her first ovulation. Cycling characteristics: cows are nonseasonally polyestrus - cycle year round estrus metestrus diestrus proestrus (poorly defined in cow) hormones: estrus cycle about 21 days in cow, about 20 days in heifer. most b/w 18-24 days. shorter than 18 d or over 24 d probably means something is wrong. estrus is day 0, the period when she shows behavioral signs of estrus. cow estrus is really short - 10-18 hours - that's it for heat. sometimes only 2 hrs. when she's in estrus, she will have a mature follicle on her ovary - 10-20 mm; and no CL of course, b/c that would mean diestrus. absence of CL, presence of dominant follicle, behavioral estrus, high uterine tone all ssuggest she's in heat. ovulation occurs after the end of behavioral estrus. in other spp, during "heat." in cow, nope. usually bout 12 hrs after estrus ends. so, if cow isn't pregnant, at about day 17 of diestrus, endometrium makes PGF2a to lyse CL. in response to lysis of CL, progesterone declines - prostaglandin in cows recall travels via local circulation from ipsilateral uterine horn to ipsilateral ovary - does not go systsemically. this is important b/c if there is severe segmental aplasia - if there is no left uterine horn, and she ovulates off left ovary, that CL will not get lysed by PGF2a from right uterine horn, so diestrus will be really really long. if she ovulates from right ovary, she'll have normal cycle. this is different from mare. in mare, PGF2a goes systemically. but anyway. CL lyses, progesterone declines. ovulation--> progesterone rises ---> day 17, PGF2a released, CL lysed --> progesterone declines -- increased FSH -->follicular growth, increased estradiol--->increased FSH and LH remember, low levels of estradiol keep LH levels low, but once estradiol levels get really high there is positive feedback, and LH surge, and that induces ovulation. etc etc. same old story. hormone are as expected. differences - estrus is short, ovulation is 12 hrs after end of behavioral estrus. you do see follicles during diestrus,a nd small peaks of FSH during diestrus. these follicles do not get large, do not ovulate, but do exist. you'll know she isn't in heat b/c of lack of uterine tone, presence of CL, and lack of estrus behavior. also low levels of LH persist during diestrus, and are required to maintain CL. but no LH surge during diestrus. Detecting Estrus: most cows are bred by AI so you need to know when she's in heat to breed at the right time. how do you know? best way is to watch for behavioral estrus. cow in heat will stand to be mounted. so watch for cows to stand to be mounted. if you do dairy work, you will be very frustrated b/c it is really lame but no one has time to sit around and stare at cows all the time. people try to watch the cows while they arae mowing the fields and running around but you have to pay attention to the cows or you can miss estrus, esp if only 2 hrs. slide: cow standing to be mounted. she is in heat. other signs of estrus in cow - less definitive than standing to be mounted: clear mucus (cervical mucus) - thick, stringy, crystal clear mucus dripping from vulva. also, uterus will have high tone, be very coiled. there will be follicles on ovary, no CL. that's all consistent with estrus. she'll ovulate 12 hrs after end of behavioral estrus. then she enters metestrus. she has corpus hemorrhagicum CH, progesterone is increasing, estrogen is declining. in response to estrogen withdrawal, you often see metestral bleeding at the vulva. this is not the same as menstruation in women, which is progesterone withdrawal causing sloughing of endometrium. this is just diapedesis of red cells across caruncles of endometrium in response to estrogen withdrawal. Diestrus: CH becomes mature CL which is usually but not always palpable on ovary. imagine if you will - the little bit of CL sticking out of surface of ovary isn't the whole thing. most of it is within the ovary, but you can still palpate it in there. slide: fluid filled CL - normal to be cystic like this. cow still cycling normally. if there is a mature CL, she's not in heat. uterus should be relatively atonic, won't feel all tubular and turgid, but will be floppier, although not doughy. day 17 - PGF2a release; ipsilateral diffusion; lysis of ipsilateral CL. presence of a follicle doesn't mean she's in estrus. follicle can be present at any stage. after regression of CL, there is a small white scar - corpus albicans. in old cow, you feel them - many old CAs that feel like tiny pimply things. they are not significant. Heat detection: important, because you're probably breeding with sperm from genetically superior bulls, to improve your herd. so you have to reliably detect heat! 6% of pregant cows still show signs of estrus behavior. If cow is confirmed pregnant, and then looks in heat, just examine her to check it out but do not panic. To detect heat, you need to allow appropriate time - should be spending about 15-30 minutes 2-3 times daily watching the cows - ONLY watching, not doing something else at the same time - we're talking undivided attention; mounts last 10-15 seconds and if you aren't paying attention you can miss them. cows are more active when cool, between 10 PM and 5 am; watching them at noon in the summer will not necessarily be useful to you. You should have trained personnel watching the cows, with no distractions. they are watching for cows to stand to be mounted by other cows. remember - poor heat detection is the NUMBER ONE cause of increased calving interval. ideal is 12 month calving interval. when heat is missed due to poor heat detection, calving interval increases. people don't notice heat, cow isn't bred on time. cycling cows are more active - mount more frequently - than pregnant cows. if five cows are pregnant, and one is open, you may not detect heat in that open cow b/c pregnant cows aren't active and may not mount her. now, if cows are tied in stanchion barn, heat is missed because you can't watch for mounting behavior. watching them after you feed them isn't useful b/c they will be eating. poor footing reduces the number of mounts as well - cows are not that stupid, they won't try to mount other cows if they think they will slip and fall. ancillary signs of heat - not definitive signs - if you breed b/c of these, you have reduced pregnancy rates. the only definitive sign of heaat is watching them standing to be mounted by other cows. slide: this cow is probably in heat - she has little rub marks on either side of her tail, indicating repeated mountings recently. if you breed her based on these signs, you probably have reduced pregnancy rate - could have happened a few days ago, could be due to rubbing on fence. the cows that are mounting, resting heads on backs of other cows, licking other cows vulva - those are near heat. clear mucus from vulva - suggests she's probably in heat but if you do not see her standing to be mounted you aren't sure. but if you see this, pay close attention to this cow in the field. Heat Detection Aids - people try to rely on these other devices, to save time. they can assist you but not replace the watching. Kaymar (??) - white sticker you stick onto tail head. pouch of red dye in it. if she's mounted, dye is released, makes red mark on sticker. this is an ancillary aid. she could roll on her back and have same result. crayons people rub on back of cows, watch for smearing electronic devices to detect pressure on back vasectomized bulls - will mount cows more than cows mount cows - increase # mounts/hr, but you still have to watch the cows and plus you have to deal with a bull which is a pain. or treat cow with androgens to increase mounting activity - still, teaser animals don't eliminate need to monitor and are more difficult to handle. need good records, good cow identification. if you see one cow mount another cow you need to know which cow was mounted. record heats when they are seen - write it down or use computer or whatever. slide: cowtown. rodeo in NJ during summer. not the highest quality but fun. hamburger walks into a bar, orders french fries, bartender says sorry, we don't serve food here. Breeding management: you have good heat detection, you see her in heat - when do you breed her? if you don't heat detect at all - pasture breeding - turn cows out with bull, hope for the best. beef herds do this. dairy herds -sometimes allow bull out with heifers to breed them, since they do not need to come in for milking or whatever. but heifers are your best genetic potential so should be bred by AI, but often aren't b/c pasture breeding is easier. if you do pasture breed heifers or beef cows or whatever, leave bull out for about 2-3 cycles - about 2 mos - then take him out, then wait about 40 days and do preg checks on everyone. not recommended for dairy cows b/c of milking schedule and b/c you need exact breeding dates to schedule dry periods. the other way iss handbreeding - detect heat, then breed via AI or natural. most people do AI with frozen semen. farm personnel watch 2-3 x daily, find cows in heat, breed 12 hrs after cow first seen in heat. assuming you're watching at least 2x daily, best time to breed is 12 hrs after first seen. breeding earlier, sperm might not live til ovulation 12 hrs after end of estrus. cow seen standing in morning, bred in afternoon; cows seen in afternoon are bred next day. metestral bleeding - if you see this, you know she's ovulated - has CH on ovary - estrogen levels falling. if you see this and you have not seen heat yet, you can try breeding - will see low preg rates, 20-30%. probably better to just accept a missed heat. you know she's just ovulated, count your days. restlessness, mounting other cows, broken Kaymar, chin resting - can breed, but you waste a lot of semen this way. best thing is to breed when you see them standing... missed heats, poor heat detection - number one cause of reduced pregnancy rates. AI advantages: -increases use of proven sires -safer and cheaper than maintaining bull on site -reduces or eliminates spread of venereal disease AI bulls have been through a big screening program. They have had a lot of calves, their daughter's lactation has been monitored. only bulls who increase milk production in their daughters get approved. it takes years for this process of proving a sire. also, if you have a bull on your farm, you have to feed it, manage it, avoid being killed by it... venereal diseases are rampant among beef herds bred by natural cover; infertility increases; campy and trichomoniasis are big in beef industry; rare in dairy b/c of AI. but you need well trained personnel who can detect heat, and do AI. and, if an AI sire has a defect no one noticed before, you could spread a genetic defect. AI disadvantages: -need trained people to do the AI -might spread genetic abnormalities -need accurate heat detection so the semen is frozen after being collected from the bulls...there are big facilities of liquid N2 tanks holding thousands of straws of bull semen. you call them up, they bring out semen and AI your cow. the tanks have to be maintained, N2 levels maintained, etc. most AI centers do this pretty well. thawing process is also important. The AI techs know how to do it. if you are asked to AI a cow, you need to know how to thaw - usually 37 C for 30-60 sec, but depends on freezing process. you usually submerge in 37 C water then take it out and dry it. you wash cow vulva, rinse, dry - take insemination gun, load straw into it, put an arm in the rectum, hold cervix, pass pipette into vulva, thread through cervical ring - use hand in rectum to manipulate the cervix over the insemination gun. you pass it into the uterine body - remember how short that is. once you get gun through cervix,advance into uterine body and deposit semen there. that way, half can go up each side and increase preg rate - if you go too far, into one horn, and she ovulates on the other side, she probably won't get pregnant. slide: minnie moo - cow with mickey on her side. we often manipulate repro cycle with hormones to try to improve production esp in dairy herds. if you miss a heat, you can use PGF2a to short cycle her and return her to heat sooner. or, you can try to synchronize a whole herd of nonpregnant cows so they all come into heat at the same time - allows you to focus heat detection over a particular week, then slack off. also, cows that are around other cows in heat, are more active and mount more. so heat detection is improved. so many people synchronize their herds routinely. you can do that a few ways, most commonly with Lutalyse (PGF2a). this shortens lifespan of CL. the problem is you have to wait til CL is mature. early CL won't respond to lutalyse. has to be 5-7 days old. if you don't feel like figuring it out, use this random method (most people do this) - give all cows 2 shots, 10-11 days apart. give first one - by chance, some are in diestrus, others are in estrus, just before estrus, just after estrus. so the ones in diestrus will lyse CL, come into heat, form another CL - then 10-11 days later they already have another mature CL. the other cows by then will also have a mature CL. then the 2nd shot synchronizes everyone to come into heat in 2-3 days. so you do a lot of cow watching then. the other way to do it is to extend life of CL with substitute progesterones - Synchramate B progesterone implant - you use a big needle - 14 ga or 12 ga - put implant in, inject it into her ear (clip and scrub first). leave it in there. this substitutes for a CL. you leave it in 9 days, then inject with PGF2a or estradiol (which is luteolytic in cows) to eliminate any actual CLs, and all should come into heat in 24-48 hrs. tighter synchrony, but more difficult. most people do the Lutalyse thing as above. Embryo Transfer: AI, ET, and IVF are pretty commonly used so we need to know about them. We already discussed AI. ET has a lot of advantages. ET means you have a valuable egg donor cow - she makes a lot of milk, you want calves from her - but she can only have one calf per year normally. that means maybe 5 or 6 calves total. Bulls make thousands of calves. ET allows you to increase cow offspring. advantages: proliferation of desirable genotypes - see above genetic improvement import and export - easier to ship embryos than cows across international borders. tx of certain types of infertility disadvantages: expensive - need valuable cow labor intensive requires highly trained personnel Technique: first, you superovulate the cow - can use FSH or similar hormone like PMSG - this recruits extra follicles on the ovary. slide- 20 follicles on these ovaries. this cow will ovulate 20 oocytes. you can't breed her and have her carry 20 calves. so you let her ovulate, you breed her with double dose of semen, then 7 days later you flush her uterus to get the embryos out. at this point, the embryos are in uterus so you can flush them more easily than if in oviduct. could do it from oviduct, surgically, a few days earlier. to do nonsurgically at 7 days, pass catheter into uterus through cervix, inflate balloon on cath, flush transport media through, drain it back out, and collect it. after you do one horn, do other horn. you get the embryos into a collecting device, look under scope for embryos...for each embryo, you isolate it, load it into a straw, put it inot one of those guns, then put it into recipient cows synchronized to be at same stage of cycle as donor cow. recipients carry calves so you get multiple calves from original donor cow. can do this a few times a year from the same donor cow. not every cycle, though. superovulating every cycle blows out the ovaries. also you should let donor have calf now and then. In Vitro Fertilizaton: IVF is getting more popular than embryo transfer. for ET, cow has to be able to conceive and get embryo from oviduct to uterus. IVF bypasses oviducts and uterus. if you have cow with ssevere endometritis, or bilateral impatent oviducts, or whatever, you can use IVF. technique: take a special U/S device, pass through vulva, insert long needle,use u/s to identify follicles on the ovary, puncture them, aspirate fluid out of the follicles and also of course the oocytes, get them into collection dish and fertilize them in vitro with capacitated bovine sperm. let it develop for hours-days, then transfer into recipient cow. this also increases number of possible offspring from a given cow. in some areas, IVF is more popular b/c you dno't have to worry about superovulation and you still get a lot of oocytes. how traumatic is this to the ovary? you're sticking needles in there. well, the place in Lancaster that does it says years of doing it doesn't seem to produce problems in the cows. oh, we use epidural anesthetic, btw. slide: cow mounting a horse ---break--- The Pregnant Cow, Part One: normal gestation and parturition in the cow: pregnancy lasts on average 280 days; range 270-290 days that's b/w 9-10 mos. We like a 12 month calving interval. So, that leaves 2.5 mos to get pregnant after she calves. so normal parturition and uterine involution is very important. There's a lot of emphasis on making sure everything goes normally for this reason. gestation length is affected by many things bull calf gestation is longer than heifer calf twins gestate 10-14 days less than singletons - if there's early parturition, always make sure to check for a twin!! you should do that anyway, but be extra sure in this case. breed and genotype of sire and dam - bos taurus more about 280 day; bos indicus have longer gestation (the zebus, etc) lengths, take longer to get pregnant again after calving, generally less efficient breeders. plane of nutrition season - winter/spring births - longer gestation older cows - carry shorter placenta: cotyledonary: this describes the attachment surface, epitheliochorial: number of layers delayed deciduate: how long it takes to get released. By cotyledonary, we mean the exchange of O2/nutrients occurs over these circular areas called fetal cotyledons on the surface of the chorion - these are the red, velvety, villous areas projecting up from fetal chorion - the villi interdigitate with the maternal caruncles. fibrosis or infection of the cotyledons results in impaired nutrient transfer. so mom's uterus has these little bumps, like little trees. the chorionic cotyledons drape over it to form the placentome. in the ewe, the placentome is sort of inverted. by epitheliochorial, we mean there are 6 layers b/w mom's and fetus' circulation. - fetal endothelium, CT, chorionic epi, endometrial epi, endometrial CT, maternal endothelium. this is also seen in horse, pig, sheep as well as cow. peopl ehave hemochorial (three layers - mom blood next to fetal chorionic epi); dog and cat have endothelochorial (four layers) (mom endothelium next to chorionic epi) delayed deciduate - after delivery, there is some endometrial sloughing. not much. nowhere near as much as in people. but some regeneration is required prior to next pregnancy. Endocrinology of pregnancy - she's tired to endocrinology but we have to do this... first 15 days: same as cycling animal. ovulation, CH, CL, progesterone rises... then, in nonpreg animal on day 17 PGF2a comes from endometrium to lyse CL. in pregnant animal, conceptus starts to secrete products - some hormones, proteins, that inhibit endometrium from secreting PGF2a. CL is maintained due to active intervention of conceptus. This results in maternal recognition of pregnancy. now, progesterone levels continue to increase and stay high through gestation. conceptus in cow rarely migrates. if oocyte comes from right ovary, embryo implanats 99% of time in right horn. pregnancy usually ipsilateral to CL, therefore. the embryo does other things too - alters vascular permeability of endometrial vessels, increasess uterine blood flow, causes histotroph (uterine milk) secretion, suppresses endometrial immune response, and contributes to mammary growth and development. in the cow, CL is maintained throughtout pregnancy. it is the primary source of progesterone. the maternal adrenals also make a lot of progesterone. after about 200 days, if you ovariectomized the cow, she could maintain pregnancy with adrenally derived progesterone. so the cow is "intermediately dependent" on the CL through the last 80 days - could possiblly do without CL if she had to. there was a case where PGF2a was given to pregnant herd that was out past 200 days - the owner freaked out but the cows did not abort. remember also - about 6% of pregnant cows will stand to be mounted. placenta/conceptus do secrete estrogenic substances. do not just rebreed all cows showing heat signs. check first. insemination will likely cause abortion. follicular development also occurs during pregnancy, but ovulation does not. Placenta makes a lot of steroids - progestogens, estrogens, and androgens. particulars not important, but bottom line - most of the placental estrogens are immediately conjugated - predominant conjugated estrogen is estrone sulfate, which can be used as a pregnancy test. starts to rise about day 60. by day 100, very high. if you find high levels you know she's pregnant and the fetal/placental unit is alive and functioning to conjugate the estrogens. estrogens rise gradually throughout pregnancy than right near term, there is a drastic surge, big sudden increase. the other thing about estrogens is that they are picked up by the mammary gland - hormone concentrations in milk are different from in plasma - that's what accounts for a lot of mamm gland development. positive signs of pregnancy estrone sulfate tests are expensive. there are four positive signs to identify on transrectal palpation. finding one of these means she's pregnant 1. fetal membrane slip: palpation of chorioallantois - in cow, gets very long, very early in gestation. it fills up both the pregnant and the nonpregnant horn. fetus and amnion are grape sized at day 40, but chorioallantois is filling up the whole uterus. so if you pick up uterine horn and feel this tissue in there, that's the fetal membrane slip. positive sign of pregnancy. 2. palpation of amniotic vesicle: feel for the grape. it's small, in a small area, you have to pick up the whole horn and feel tip to base on both sides to find it. if you find it, she's pregnant. it's also fragile, so you don't want to squish it and pop it. 3. palpation of the fetus: this is pretty obvious. if you stick your arm in and feel a calf, you know she's pregnant. this is the one of the four signs people always forget. 4. palpation of the placentomes - the cotyledon/caruncle bumps. the maternal caruncles get big and change size with stages of gestation, and you can feel this. circumstantial signs of pregnancy: these suggest the cow is pregnant, but are not definitive like the above four are. 1. fluid in uterus - suggests pregnancy, but could be hydro, muco, or pyo metra 2. thinning of uterine wall - enlarged uterus has thinner wall - as above 3. fremitus of the middle uterine artery - you feel "buzzing" of this artery, which is the main supply to the uterus - 6 mos or later of gestation. but this is also seen after abortion, b/c it takes time to involute to prepartum size - days to weeks. 4. presence of CL at 18-24 days post breeding - consistent with pregnancy, or segmental aplasia, or breeding at wrong stage of cycle, or early abortion with maintenance of the CL Early pregnancy dx: finding pregnant cows is important. once you tell farmer cow is pregnant, the work is done. she is on schedule. if she isn't, he has to pay more attention to her, short cycle her, breed again. finding open cows is key. the goal is to identify pregnancy before 42 days after breeding. 21 days is ideal but impossible. so you hvae to write off the first postbreeding cycle. but you want to know before the second heat so you could rebreed. 35-65 days: amnionic vesicle is palpable by 40 days: fetal membrane slip Estimating stage of gestation: if animals were pasture bred, farmer will ask about this. he/she wants to knwo when cows will deliver calves. day 60: fetus=mouse, placentome=pea, day 90: fetus=rat; placentone=dime, 120: fetus=cat; placentomes=quarter 150: fetus=beagle; placentomes=half dollar; (not on exam) b/w 35-40 days you just say "pregnant" or "non pregnant" - you knwo the breeding date so stage isn't important. you need to know how to estimate stage for beef cows and dairy heifers, though. 60-70 days - conceptus about size of grapefruit; harder to do membrane slip b/c horns are bigger, can't get hand around it. this guy is driving and he has a cop following him who sees 2 penguins in back seat. pulls him over and says take these penguins to the zoo or i'll arrest you. guy says ok. but a week later, the cop sees the same guy with the same penguins who now have sunglasses and beach toys - guy says, i did take them to the zoo, now i'm taking them to the beach! alternate means of pregnancy diagnosis - rarely used. but if cow will not allow palpation or you can't palpate for some other reason, there are other ways: milk progesterone assays (not popular): high 21 days postbreeding suggests pregnancy IF heat detection was good. otherwise same probs as using CL for preg dx. see above. could be high w/o pregnancy estrone sulfate assay: reliable after 100 days but $$ and late balottment of fetus (6 mos and later) Parturition: very exciting. if you do any obstetrical work as a large animal work - it's great to learn obstetrics in cows, b/c parturition is relatively slow, straining isn't so extreme, there is more time and room for error - so if you plan to be a horse vet, start with cow obstetrics. signs of parturition: -with accurate breeding date, can predict date -2 days prior: udder gets big, edematous, swollen, turgid -dissolution of cervical mucus plug and clear mucoid vulvar d/c 24 hrs before -sacral ligament relaxation most of the time, you don't know exactly when she's going to calve, you just watch for stage I endocrinology of parturition - she's had high progesterone for 9 mos. the onset of functioning of fetal hypothalamic/pituitary/adrenal axis signals parturition. a dead/impaired fetus will delay parturition. fetal adrenals get more sensitive to ACTH, start making more cortisol. placenta starts to make estrogens out of progestogens. progesterone decreases, estrogen rises. about 2 weeks before parturition, then, progesterone drops as fetal cortisol rises. estrogen also rises. this causes increased oxytocin receptors on myometrium to form. oxytocin binds receptors - uterus starts to make prostagandins in response to that, a few days prior to delivery. as prostaglandins rise, CL is lysed, progesterone drops precipitously. prostaglandins and oxytocin together cause uterine contractions. fetus move to cervix, stretches it, triggers ferguson's reflex, triggering surge of oxytocin, causing dramatic contractions, and expulsion of fetus. fetal glucocorticoid --> drop in maternal progesterone and rise in estrogen --> increased oxytocin --> increased prostaglandins --> etc. also there is a rise in prolactin and relaxin prior to parturition for milk production and relaxation of pelvis. stages of labor - need to know what is normal and what is not. with cows, generally farmers only call you if there is a real problem. I: onset of uterine contractions. starts with that and ends with rupture of chorioallantois. 1-24 hrs, usually not noticed. sometimes some restlessness, pacing. perhaps looking back at side. II: from rupture of membranes to expulsion of calf - longer than in mare, normally 1-4 hrs. sometimes shorter but up to 8 hrs still considered normal sometimes. heifers take usually 3-4 or up to 8 hrs. so it's long, slow process compared to mare. release of allantoic fluid from vulva signifies onset of stage II. once you see that, calf should be out usually by 4 hrs, or up to 8 in heifer. but if there is an obvious problem, you don't wait 8 hrs. if you see a tail coming out the vulva, don't wait 8 hrs! if you see two feet and a nose and it looks ok you can wait a while. but if cow doesn't strain, or there is no progress over two hours, then you may want to intervene. but you do not want to intervene too soon if you don't have to, because the cervix can tear. typically wait 1 hr in cows or 2 hrs in heifer before considering intervention, after rupture of membranes. III: passage of membranes - usually w/in 6 hrs. if not by 12 hrs, considered retained. ---end---