3Meso metrium suspends the uterus to the abdominal roof- in dogs and cats
4Uterus anatomyPerimetrium- outer lining Myometrium- muscular layer Endometrium- inner vascular lining Clitoris- just inside the vagina on the floor Vaginal Fornix- lateral separation of the distal vagina that creates difficulty in A.I. of unaware
6Hymens do occur in dogs and mares and can increase dystocia if a fibrous band is maintained When the vaginal canalization is complete, the fetal hymen is formed from the proliferation of the sinovaginal bulbs (where müllerian ducts meet the urogenital sinus), and becomes perforate before or shortly after birthDue to similar reproductive system development, many mammals, including chimpanzees, elephants, manatees, whales, and horses, retain hymens
7Factors that affect puberty Genetic factors- smaller breeds reach puberty earlierNutritional factors-poor nutrition delays onsetEnvironmental factors- presents of males enhances puberty, confinement and close grouping of gilts hastens puberty
11Graffian follicle- fully developed which is producing Estrogen from it fluid Corpus Hemorrhoragicum- the fill site after rupture of follicle
12Graffian (mature) follicle A granulosa cell or follicular cell is a somatic cell that is closely associated with the developing female gamete (called an oocyte or egg) in the ovary of mammals.
13Also FSH stimulates granulosa cells to convert androgens (coming from the thecal cells) to estradiol . However, after ovulation the granulosa cells produce progesterone. The progesterone may maintain a potential pregnancy and causes production of a thick cervical mucus that inhibits sperm entry into the uterus
15The theca folliculi are responsible for the production of androstenedione, and indirectly the production of estradiol by supplying the neighboring granulosa cells with androstenedione a substrate for estradiol.
16From the Anterior pituitary Gland Follicle-stimulating hormone (FSH) is a hormone. It is synthesized and secreted by the anterior pituitary gland. FSH regulates the development, growth, pubertal maturation, and reproductive processes of the body. FSH and Luteinizing hormone (LH) act synergistically in reproduction
17From the Anterior Pituitary Gland Luteinizing hormone (LH) is a hormone produced by the anterior pituitary gland.In females, an acute rise of LH called the LH surge triggers ovulation( with Estrogens and Prostaglandin F2 alpha)Prostaglandin F2 alpha stimulates breakdown of the Tunica albiginea at the potential rupture sight on the ovarydevelopment of the corpus luteum.In males, where LH had also been called interstitial cell-stimulating hormone (ICSH), it stimulates Leydig cell production of testosterone.
19Progesterone steroid hormone involved in the female reproductive cycle, pregnancy (supports gestation) and embryogenesis of mammals. Progesterone belongs to a class of hormones called progestogens .Progesterone is commonly manufactured from the yam family, Dioscorea
21Corpus Hemorrhoragicum- the fill site after rupture of follicle- Corpus Luteum fills – production of Progesterone to maintain pregnancy
22Degeneration of C.l. to Corpus albicans in the ovary Here is an ova in ovarian tissue surrounded by theca cells and waiting for appropriate hormonal stimulation to begin to develop. FSH, Estrogen, Prostaglandin, Progesterone
23Ova to zygoteFemales are born with all the ova they will ever produce, ovulating one (moniprrous) or several (pleuriparous) from puberty until menopause. When it's time for the egg's great adventure, the ovarian tissue that encases eggs proliferates and becomes differentiated into granulosa and theca cells, producing the much larger, cystic Graafian follicle. When mature, the follicle ruptures, and the egg explodes from the torn surface of the ovary (occasionally producing a pain) and is swept up into the nearby fallopian tube, where, if sperm , fertlize and converted it into a zygote that begins dividing. This early embryo continues its way down the tube and into the uterus, where it implants itself into the uterine wall
24Fertilization occurs in the Fallopian Tube(oviduct) At Ovulation the Fimbria (funnel) gathers the ova to begin the migration down the fallopian tubeFertilization occurs in the Fallopian Tube(oviduct)
26ProestrusOne or several follicles of the ovary are starting to grow. Their number is specific for the species. Typically this phase can last as little as one day or as long as 3 weeks, depending on the species. Under the influence of estrogen the lining in the uterus (endometrium) starts to develop. Some animals may experience vaginal secretions that could be bloody. The female is not yet sexually receptive
27Estrus"Estrus" redirects here. For other uses, see Estrus (disambiguation).Estrus refers to the phase when the female is sexually receptive ("in heat," or "on heat"). Under regulation by gonadotropic hormones, ovarian follicles are maturing and estrogen secretions exert their biggest influence. She then exhibits a sexually receptive behavior, a situation that may be signaled by visible physiologic changes. A signal trait of estrus is the lordosis reflex, in which the animal spontaneously elevates her hindquarters.In some species, the labia are reddened. Ovulation may occur spontaneously in some species (e.g. cow), while in others it is induced by copulation (e.g. cat). If there is no copulation in an induced ovulator, estrus may continue for many days, followed by 'interestrus,' and the estrus phase starts again until copulation and ovulation occur.
28MetestrusDuring this phase, the signs of estrogen stimulation subside and the corpus luteum starts to form. The uterine lining begins to secrete small amounts of progesterone. This phase typically is brief and may last 1 to 5 days. In some animals bleeding may be noted due to declining estrogen levels
29DiestrusDiestrus is characterised by the activity of the corpus luteum that produces progesterone. In the absence of pregnancy the diestrus phase (also termed pseudo-pregnancy) terminates with the regression of the corpus luteum. The lining in the uterus is not shed, but will be reorganised for the next cycle
30AnestrusAnestrus refers to the phase when the sexual cycle rests. This is typically a seasonal event and controlled by light exposure through the pineal gland that releases melatonin. Melatonin may repress stimulation of reproduction in long-day breeders and stimulate reproduction in short-day breeders. Melatonin is thought to act by regulating hypothalamic pulse activity of gonadotropin-releasing hormone. Anestrus is induced by time of year, pregnancy, lactation, significant illness, chronic energy deficit, and possibly age
31FrequencySome species, such as cats, cows and domestic pigs, are polyestrous and can go into heat several times a year. Seasonally polyestrous animals or seasonal breeders have more than one estrous cycle during a specific time of the year and can be divided into short-day and long-day breeders:Short-day breeders, such as sheep, goats, deer, foxes, elk—are sexually active in fall or winter.Long-day breeders, such as horses and hamsters, are sexually active in spring and summer.Species that go into heat twice per year, such as most dogs, are diestrous.Monoestrous species, such as bears, foxes, and wolves, have only one breeding season a year, typically in spring to allow growth of the offspring during the warm season to survive the next winter.A few mammalian species, such as rabbits do not have an estrous cycle and are able to conceive at almost any arbitrary moment
32CatsThe female cat in heat has an estrus of 14–21 days and is an induced ovulator. Without copulation she may enter interestrus before reentering estrus. With copulation and in the absence of pregnancy, cycles occur about every three weeks. Cats are polyestrous but experience a seasonal anestrus in autumn and late winter
33DogsA bitch is diestrous and goes into heat typically twice every year, although some breeds typically have one or three cycles a year. The proestrus is relatively long at 5–10 days, while the estrus may last 5-21 days. With a diestrus of 5-10 days, a typical cycle lasts about 3 weeks followed by about 150 days of anestrus. They bleed during this time, which will usually last from 7–13 days, depending on the size and maturity of the dog. Ovulations occur at the end of the estrus period, therefore this is the best time to begin breeding. Proestrus bleeding in dogs is common and is caused by diapedesis of RBCs from the blood vessels due to sudden withdrawal of estrogen hormone.
34HorsesA mare may be 4 to 10 days in heat and about 14 days in diestrus. Thus a cycle may be short, i.e. 3 weeks. Horses mate in spring and summer, autumn is a transition time, and anestrus in winter.A feature of the fertility cycle of horses and other large herd animals is that it is usually affected by the seasons. The number of hours daily that light enters the eye of the animal affects the brain, which governs the release of certain precursors and hormones. When daylight hours are few, these animals "shut down," become anestrous, and do not become fertile. As the days grow longer, the longer periods of daylight cause the hormones from the anterior pituitary (FSH) which activate the breeding cycle. There is economic advantage, given a gestation period of about eleven months, it prevents them from having young in winter which forage, and nutrition is in minimum supply. This is why these animals reproduce during certain times of the year.
35RatsRats typically have rapid cycle times of 4 to 5 days. Although they ovulate spontaneously, they do not develop a fully functioning corpus luteum unless they receive coital stimulation. Fertile mating leads to pregnancy in this way, but infertile mating leads to a state of pseudopregnancy which lasts about 10 days. Mice and hamsters have similar behaviour . The events of the cycle are strongly influenced by lighting periodicity .A set of follicles start to develop near the end of proestrus and grow at a nearly constant rate until the beginning of the subsequent estrus when the growth rates accelerate eightfold. They then ovulate about 109 hours after starting growth. Oestrogen peaks at about 11am on the day of proestrus. Between then and midnight there is a surge in progesterone, LH and FSH, and ovulation occurs at about 4am on the next, estrus day. The following day, metestrus, is called early diestrus or diestrus I by some authors. During this day the corpora lutea grow to a maximal volume, achieved within 24 hours of ovulation. They remain at that size for 3 days, halve in size before the metestrus of the next cycle and then shrink abruptly before estrus of the cycle after that. Thus the ovaries of cycling rats contain three different sets of corpora lutea at different phases of development.
36Estrus frequencies of some other mammals: Ewe: 17 daysBovine: 21 daysGoat: 21 daysSow: 21 daysElephant: 16 weeks
37Estrus in the cow (polyestrous) Estrus lasts 16 hrs (Estrous cycle is 21 days)standing to be mountedMounting other cowsMucous smeared on the buttocksNervousSeeks the bullRoughening hair at the tailheadChin resting on rumps of other ocws, tail raised, urination standing heatSuper cattle
39Estrus in the ewe seasonally polyestrus (17 days cycle) Standing to be mounted\search out ramVulva swellsNervousVibrating, agitating movement of tailLength of estrus ( 30 hrs)sheep mating
40Estrus in the Sow- polyestrus Estrus 44 hrs (Estrous cycle- 21 days)Stands to be mountedNervousTries to mount othersSwollen red vulva/ mucous dischg rarelymating pigs- note earnotching for identification
41Estrus in the mare- seasonally polyestrus Estrus- 6 days ( Estrous cycle 21 days) Nervous Interst in stallion Vaginal winking, and urine excretion mare winking, in heat
42Estrus in the Bitch- diestrus Estrus – 6-21 daysBleeding begins at proestrus and decreases or stops at estrus ( Diapedesis because of increasing thickness and vascularization of the endometrium ( not shedding of mucosa as in menstration in humans)Fertility is highest 48 hrs prior to the end of estrus.Many develop pseudocyesis (false pregnancy) during C.L. production of progesterone.Metestrus – regression of the C.L.Anestrus-
45Are these cornified or non- cornified epithelial cells- what stage of Estrous cycle does this most likely represent?
46Uterine changes in Estrous Cycle -Rising Estrogen in prosestrus- edema and thickening of uterine wall- additional blood vessels -Estrogen makes endothelium fragile -Bleeding may occur in proestrus -Great media for growing excessive amounts of bacteria
47Increase in Progesterone at metestrus and diestrus- glands develop in the uterine wall and secrete Uterine Milk which nourishes the embryo until a placenta is formedAs the C.L. is killed and stops producing progesterone, the uterus lining sloughs and is reabsorbed- effects ofPGF 2alphaA. From the uterus at the end of DiestrusB. From pregnant uterus a parturitionC. From drugs (Estrumate, Lutalyse) at post estrus
48Prostaglandin F2alphadestroys the C.L which allows initiation of new cycle
49Prostagland stops C.L. and commenses a new cycle
51GnRH (gonadotropin releasing hormone) -produced by the pituitary gland (to induce it to produce FSH and LHGnRH is turned off by Progesterone (so that no new follicles are produced during pregnancy)Factrel and Cystorelin to stimulate follicle development and create a LH spike
53Estrogen Produced by Graffian follicle/induces sexual receptivity Causes uterine edema, increased vascularity and blood vessel fragilityUsed in Ear implant growth promotants- inhibits hypothalmus to produce GnRH and shuts off the pituitary gland production of FSH/LH, animals stay settled and gain better
54Progesterone Produced by CH and CL and placenta in some species Uterine wall glandular development for pregnancyInhibits hypothalamus from producing GnRH, therefore no FSH and LHMegestrol acetate (MGA) to arrest cycle until it is removedOvaban- for dogs
55Double muscling and infertility Homozygous for myostatin growth differential factor 8
56Homozygous for Myostatin (GDF8) Animals lacking myostatin do not have the ability to inhibit muscle growth.It is a genetic mutation that inhibits regulation of differentiation of muscle fibersIt is closely liked with genes associated with fertility, thus there can be a combination of these abnormal geneshuman double muscle or drugs
57Some facts as a guide for studying all species Iength of estrous cycle in cows- 21 daysLength of each of the 4 stages of cycle-Estrus hrs Metestrus- 2-5 days Diestrus days Prosestrus 3-5 daysOvulation hrs postestrusSexual maturity mo, smaller is earlierFirst bull breeding 14 mo. , mature bull=12 cowsBull sperm declines at 7 yrsHow long does breeding act take- one thrustWhat is the semen volume – 6-10 mls
58Study guide for cow reproduction What is the trade name of synthetic PGF2alphaat what stage of the cow cycle will these prepsEffective- Diestrus- why?Gestation length- 285 daysCows should be re-bred by 60 days pp (three heats pp)Cows should be dry for 60 days prior to deliveryLochia- discharge of clear fluid a couple of weeks prior to calving7% have Retained Placentas
59Study guide for cattle reproduction Silent heats are unusual and occur most often at -the first heat after calving (most are unobserved)Why is GnRH sometimes given at estrus of repeat breeders (pathophysiology of hormones and cycles)Rectal palpation for pregnancy is 3 wks gestation
60Capacitation of sperm and the female reproductive tract storage capaciation- the acrosome of the sperm heat becomes leaky- releases enzymes which break down the outer coating of the egg.Sperm in the reproductive tract of cows, pigs and sheep travel to the oviduct isthmus( a sperm reservoir (like the epididymis)There is a lower temperature, nutrients that are stimulated by the ovary and the follicle, and seminal fluid matrix is processed for nutrientsStores sperm for impending ovulation( what is the implication of this new information? to egg with capacitation and “love”
61Reproductive pattern Horses Anovulatory Phase(seasonally anestrous)Induced by lengthening photoperiodsResistant to drug manipulation at this time because Ant. Pit is not receptive to GnRH unless lengthening photoperiodCycles every 22 daysTransition Phase Spring increasing FSH but lacking adequate LH( can use Altrenogest-Regu-Mate- progesterone analog daily x 7)
62Breeding on “Foal Heat” 6-15 days post partum Breeding on “Foal Heat” 6-15 days post partum-First ovulation cycle post partum-Foal Heat diarrhea-Usually hand bred because of danger to the foal and danger to the stallion-Mare is often very anxious around the foal (diploid)
63Teasing procedure in equine breeding Horse breeding videoTeasing procedure in equine breedingBring the stallion near and watch the mare response- violent or winkingTease daily until mare is standingUse breeding hobbles/ twitchEncourage stallion until full erectionMounting is along side- intromissionVigorous pelvic thrust (10-sec)8 seminal jets (70 mls of semen)Stallions may hold mare’s withers with teeth
64Equine reproduction cycle variations May ovulate without showing estrusMay show estrus without ovulatingCL may persist up to 2 months“Split heat” is common ( in heat a few days, then out, then back in)Estrus- often multiple follicles (ovary is kidney shaped), uterus is soft and edematous, not turgid like a cow, cervix is relaxed and open
65Equine reproduction variables Late Estrus- LH surges over several days with 20 % multiple ovulations (follicles are 5 cm diameter),One twin is usually absorbedBest breeding time- 2 days pre-ovulation( three days after the beginning of estrus, and alternate days (sperm survives 2 days in the uterus
66Metestrus in the mare Diestrus in the Mare - LH fades, estrogen fades, progesterone risesCorpus hemorrhagicum forms inside the ovaryUterus is tonedRejects the StallionDiestrus in the MareProgesterone dominates , C.L. is presentCan use Lutalyse to shorten the cycle- go to proestrusCervix tightly closed
67Proestrus in the mare PGF2alpha kills C.L. Gestation Period days (11 months)Light horse have longer gestation than heavy horse breedsMale fetuses have a slightly longer gestation
68Caprine reproduction Puberty 6-8 mo, bucks- 3 mo Does need the scent emitted from the buck to stimulate her to cycle (scent glands are medial and caudal to the horns)Female bleats, flags, vulva swollenIncrease in milk productionBreed as soon as estrus occursGestation 145 days (5 months)
69Ovine Reproduction Estrus- tail twitch Often use teaser rams (vasectomized) with a marking harness“Flushing”- increasing plane of nutrition prior to breeding seasonBreed ASAP when estrus occurs1 ram= 30 ewes (synchronized using progesterone tampons (14 days then remove)
70Pregnancy toxemia in ewes and does When a pregnant ewe takes ill, a likely cause is pregnancy toxemia. Pregnancy toxemia goes by several other names including pregnancy disease, twin lamb disease, lambing paralysis, and ketosis.Pregnancy toxemia is a metabolic disorder caused by low glucose concentrations in the blood and excessive breakdown of body fat to compensate. "Ketones" are the toxic by-product produced during this rapid breakdown of fat, and it is possible to test for their presence in the ewe's urine.Inadequate nutrition during the last one-third of pregnancy is the primary cause of low blood sugar/pregnancy toxemia, as ewes cannot consume enough feed (energy) to meet the demands of their growing fetus(es).
71Pregnancy toxemia in ewes and does Successful treatment of pregnancy toxemia requires early detection and steps to quickly meet the energy (glucose) needs of the affected ewe. The most common treatment is to drench ewes with 2 to 3 ounces of propylene glycol 2 to 3 times daily. Yogurt mixed with water will also provide energy and bacteria to stimulate the rumen. Intravenous glucose is another possibility, but harder for producers to do on the farm.
72Porcine reproduction-population Breeding Originally were seasonally polyestrous
73Gilts mature at 5-8 month of age (170-220 lbs) Hastens puberty if they visit the boar each day at 150 days-Estrus day-Estrous cycle- 21 days-Stands for mounting whichCan be tested by hand-Pressure on their back orRiding them-Estrus occurs 5days afterWeaning and is fertile_Batch breeding of sow allWeaned at the same time-Gestation- 3mo, 3wks,3days(115 days)
74Boars can’t smell females in EStrus Females respond to Saliva of Boars champing which contains pheromonesBoar ejaculation minmls1st fraction-clear prostatic fluid2nd fraction- sperm rich3rd fraction- thick gel frombulbourethral gland
75Estrus Synchronization in Animals Cattle- cycle 21 days practised most often in dairy cattle- batch breeding in pigs- shorten theCalving interval in for beef cattle can be shortened. 2/3 of cows will be in diestrusPGf2alpha lyses CL only works in Diestrus (Estrumate), can repeat in 11 daysSheep- Cycle days Estrumate as in cows or use Veramix progesterone sponges- preventsOvulation and no new cycles can begin.CL present will mature and be eliminatedGoats- Cycle 21 days- EstrumateHorses- Cycle 21 days- LutalyseSow - Cycle 21 days Estrumate has noeffect until 12 days post partum and theycycle 2-5 days post weaning- use wean-as the synchronization method.
77Disturbances of Estrus in Large animals cow- Retained C.L. and pyometra- anestrus after parturition (15-60 days) C.L. normally dies at 17 days pp. Cervix is open and uterine manipulation reveals large amount of purulent material from vaginaTtt – Estrumate kills C.L.
80Follicular cysts cattle Enlarged follicular structure greater than 25 mm persisting for 10 days or more in the absence of a corpus luteum. Follicular cysts are thin walled, fluid filled, and anovulatory. These cows can have anestrus type behavior or have nymphomania behavior (always standing tobe mounted). The uterus isgenerally flaccid, and theymay have a constant cleardischarge from the vulva.Most of the time there aremultiple follicular cysts.Progesterone concentrations are low.
84Follicular cysts- horses Most common reason for anestrus during the breeding seasonPurulent material does not accumulate because the cervix is NOT partially open like in the cowTreat with Lutalyse (Estrumate is not for horses)
88Canine Reproductive patterns Onset of Puberty- great variationSilent heat- no outward signs of estrusIdeal breeding age: after 2 year of ageAfter genetic screening for defectsEstrus- every 7 mo. ( Shepherds every mo)- once per year- Basenji
89Non-cornified epithelial cells in vagina Parabasal cells have a large stippled nucleus and a rounded cytoplasm The nucleus is large compared to the cytoplasm.
90Non-Cornified epithelial cells of the vagina Intermediate cells have a have a stippled nucleus and more cytoplasm than parabasal cells. The cytoplasm may even become angular.
91Cornified epithelial cells of the vagina Superficial cells have a pyknotic nucleus and angular cytoplasm. There is no stipling in the nucleus.
92Cornified epithelial cells of the vagina Anuclear cells have no visible nucleus and angular cytoplasm.
93InterestrusInterestrus consists of diestrus (60 days) plus anestrus (a variable time).Average duration is 7 months.G. Shepherd dogs average about 6.5 months interestrus.Dachshunds average about 8.3 months interestrus.Basenjis average about 12 months interestrus.Therefore, larger dogs tend to have shorter interestrus intervals than small dogs (contrary to popular opinion)The variation of the interestrus interval within a bitch was actually found to be greater than that between bitches in a research study done by Dr. Guy Bouchard.Interestrus tends to become longer as bitches are greater than 8 yrs
94AnestrusAnestrus is not the same as interestrus. Anestrus is a variable time after diestrus. Interestrus (diestrus + anestrus) averages months.Anestrus lasts days (anestrus does not include diestrus).Anestrus is a time of mandatory endometrial repair that has been documented in BeaglesThe endometrium is being 'repaired' after the progesterone effects during diestrus for the preceding 60 days
95AnestrusIntermediate and parabasal cells predominate in smears taken during anestrus. Superficial cells are absent or found in very small numbers. Neutrophils may also be present or absent.
96AnestrusProgesterone is at baseline concentrations (<1 ng/ml). Even spayed bitches run basal levels of progesterone. This baseline progesterone is probably of adrenal origin.Prolactin secretion by the pituitary may promote anestrus, because prolactin inhibitors can be used to terminate anestrus (i.e. induce estrus).
97ProestrusSerum concentrations of estrogen rise during proestrus, leading to capillary breakage and leakage of red blood cells through uterine epithelium, as well as proliferation of the vaginal epithelium.Examination of vaginal smears from early to late proestrus will reveal a gradual shift from intermediate and parabasal cells to superficial cells. Typically, red blood cells are present in large numbers and neutrophils are commonly observed. Large numbers of bacteria are also often present.
99proestrusIn some bitches, proestrus can persist for two to three weeks. In such cases, prolonged lack of receptivity may suggest the need to artificially inseminate or force-breed the animal. Examining vaginal smears in such cases will alleviate such concerns - certainly, if more than a very small percentage of cells are parabasals and small intermediates, breeding is a waste of time.
100EstrusThe defining characteristic of cytologic estrus is the predominance of superficial cells. Most, but not all, bitches will undergo full cornification, and the smear will reveal a monotonous pattern composed almost exclusively of anucleate superficial cells.
104If the bitch has been bred within a day of preparing a vaginal smear, it is quite likely that sperm will be observed among the epithelial cells. Indeed, careful examination for sperm in a smear taken within a few hours of an alleged breeding is a fairly reliable means of confirming or denying such an incident.
105In the image below, an intact sperm (left panel) and a sperm head (right panel) are present next to superficial cells.
106DiestrusThe onset of diestrus is marked by a precipitous decline in the number of superficial cells and reappearance of intermediate and parabasal cells. Most commonly, the cellular profile changes within a single day from essentially 100% superficial cells to less than 20% superficial cells. However, it is best to confirm the onset of diestrus by examining a smear prepared on diestrus day 2.
107DiestrusThe significance of identifying the onset of diestrus is that it is a considerably more accurate predictor of the time of ovulation, and hence gestation length, than sexual behavior.
111Dogs ovulate 5-7 days prior to the onset of diestrus (7-9 days after the preovulatory LH surge), and hence, gestation length is usually day from the onset of diestrus day. The period of behavioral estrus is variable, and often extends up to several days before and/or after cytologic estrus. Gestation lengths calculated from the onset or cessation of receptivity are correspondingly inaccurate. The onset of diestrus also correlates well with loss of fertility, and breedings after the diestrus shift are rarely fertile.
113Normally, LH is present in the bitch's blood in very small amounts Normally, LH is present in the bitch's blood in very small amounts. Just prior to ovulation there is a significant increase in the serum LH value. LH will then return to the baseline level within a 24- hour time period.It is this surge of LH that triggers ovulation and therefore determines the fertile period of the bitch. The LH surge may occur any time from 3-28 days after the first signs of heat (swelling of and bleeding from the vulva). The average is 8-12 days. Ovulation will occur approximately 2 days after the LH surge. The eggs will require an additional 2-3 days to mature so that fertilization may take place. The eggs are viable from 48 to 72 hours after maturity. Therefore the fertile period of the bitch averages 4-7 days or 5-6 days after the LH surge.
123· NipplesNipples on Pregnant dogFrequently the first change noticed in a pregnant dog is in the breast. Before pregnancy takes place, a dog goes through a cycle called Estrus. This is the period of time in which a dog can conceive. If the female becomes pregnant hormones cause the breast to enlarge. More specifically, the nipples become swollen soon after the pregnancy occurs. These growth and swelling changes will continue throughout the pregnancy in preparation of feeding the puppies when they arrive.
124AppetiteFeed More OftenMany dogs lose their appetite during very early pregnancy. They may eat less or sometimes not at all. After approximately 2 weeks their hunger comes back to the point that the dog may seem to want to eat all the time. Their bodies are using the food at a much faster rate to support themselves and however many puppies that are developing. Dogs should be fed almost double the amount of their usual food before pregnancy
125Morning SicknessSick DogLike humans, pregnant dogs can suffer from morning sickness early in the pregnancy. Some dogs won't experience it at all and others will vomit intermittently. It rarely lasts longer than 2 weeks or causes problems as long as the dog does not become dehydrated from vomiting.
126StomachPregnant StomachBesides the nipple changes, a pregnant dog will experience other changes in the stomach as the puppies grow. The stomach becomes visibly extended mid-pregnancy. As the process continues the puppy's movements can be seen under the belly. The mother gains body weight as well as the weight of the puppies and placenta. A very pregnant dog with a large litter will look like she's about to pop. Dogs with short legs may actually have trouble walking during the last week or so of pregnancy.
127NestingAs the pregnancy draws to a close the dog will start seeking a place to give birth away from everything else. This is called nesting. They may start crunching rugs together with their paws or start resting in a particular corner that's out of the way. Some dogs may choose something familiar that represents security to them, like your bed. For that reason, it is best to arrange an out of the way place for her with an old blanket, familiar toys and extra food and water bowls. Doing this early in the pregnancy helps the dog become familiar enough with that spot so she will feel safe giving birth there.
128BehavioralOne sign of pregnancy, through the pregnancy and birth, are behavioral changes. A friendly dog may suddenly exhibit a need to stay away from people, even those she knows. On the other hand, a dog that has never been that friendly may suddenly love to be petted and be playful. While giving birth, some dogs will want to be left alone and some will need a reassuring voice or hand. It all depends on the dog. Be aware that dogs and animals in general are very protective of their young, so the new mother should be allowed to get to know her new family without anyone handling the puppies or making unnecessary visits until they are older.
135Domestic cat reproductive cycle 2-4 estrous periods every year, each lasting days. If she is bred, estrus seldom lasts more than 4 days. If successful mating does not occur, a heat cycle may last for 7-10 days and recur at day intervals. It is possible for an unmated female to cycle every 3-4 weeks indefinitely. Cats also have an estrous period 1-6 weeks after giving birth, so a female may be nursing one litter while pregnant with another.
136Domestic cat Estrous Cycle Females will not ovulate unless her cervix is stimulated by copulation or by artificial means(moist Q-tip)Rabbits, ferrets are the sameIf not stimulationin heat 10 days, follicles regress, thenagain in 10 daysEstus 3-40 hrs post ovulation, metestrus 2 days, then diestrus 30 to 50 days.
138start howling and this can go on for several minutes at a time. Some females can even spray urine in the same manner that is usually associated with tomcats - lifting the tail and squirting urine on a vertical surface.The female cat may adopt postures suggestive of a desire to mate - tail raised, rear end held high
139Seasonally polyestrous- induced by lengthening daylight Inducted ovulators- gestation days
141queens kept under a minimum of 10 hours (12 to 14 hours is better) of artificial light per day may cycle all year round. Cats kept in eight hours of daylight (and 16 hours of dark) will virtually stop cyclingqueens are described as induced ovulators
142Margay Reproduction and life cycle Female margays are in estrus for four to ten days overa cycle of 32 to 36 days, during which they attract males with a long, moaning call. The male responds by yelping or making trilling sounds, and also by rapidly shaking his head from side to side, a behavior not seen in any other cat species. Copulation lasts up to sixty seconds, and is similar to that in domestic cats; it takes place primarily in the trees, and occurs several times while the female is in heat.Gestation lasts about 80 days, and results in the birth of only a single kitten (or, very rarely, two), usually between March and June. The kittens weigh 85 to 170 grams (3.0 to 6.0 oz) at birth. This is relatively large for a small cat, and is probably related to the long gestation period. The kittens open their eyes at around two weeks of age, and begin to take solid food at seven to eight weeks.
144Gamete TransportFertilization depends upon the two gametes bumping into one another. In species with internal fertilization, which includes all mammals and birds, both sperm and egg must be transported into the oviduct, which serves as the site of fertilization.Sperm survive up to 6 days in the uterine horn
145Placentation in Dogs and Cats Dogs and cats are well-known members of the group of species that have zonary placentae. Other examples of animals with this type of placentation include mustelids (ferrets, skunks), bears, seals and elephants
146ImplantationDogs and cats are litterbearing species, and prior to fixation and implantation, the blastocysts become evenly spaced throughout the uterine horns. In both species, there appears to be efficient transuterine migrationGestation days
147In dogs, implantation occurs roughly 18 to 20 days after the preovulatory LH surge (about diestrus day 8 to 10). In cats, implantation has been reported to occur 12 to 14 days after mating.
148Gross Structure of the Placenta The zonary placenta takes the form of a band that encircles the fetus. In dogs and cats, it is complete, while in species like ferrets and raccoons, it is incomplete (i.e. two half bands).
149Cats typically have 3 to 8 fetuses Cats typically have 3 to 8 fetuses. It is not unusual for one or more to die in utero and the others survive to be born. This image shows the end of one uterine horn. The zonary placentae of two fetuses are clearly visible through the uterine wall.
150Dissecting the uterus away from the conceptuses reveals the chorioallantois as an ovoid structure modified circumferentially to form the zonary placenta.
151In this image, the chorioallantois has been dissected away to show the fetus, encased in its amnion
152When the placenta is opened up, its rich vasculature and the umbilical vessels of the fetus are evident. (Note: the amniotic fluid is crystal clear, but looks dark due to the background.)
153The canine placenta looks very similar to that of cats The canine placenta looks very similar to that of cats. A feature usually seen in the placentae of both species is marginal hematomas (hematophagus zones). These are bands of maternal hemorrhage at the margins of the zonary placenta. The products of hemoglobin breakdown give them a distinctly green coloration in dogs, whereas in cats they are brownish and usually less obvious
154Microscopic Structure of the Placenta Dogs and cats have an endotheliochorial type of placenta. In this type of placenta, the endometrial epithelium under the placenta does not survive implantation, and fetal chorionic epithelial cells come to be in contact with maternal endothelial cellssurrounding the central third of the chorioallantois proliferate to form a syncytium
155erodes through the endometrial epithelium and flows around maternal capillaries. Initially, the invading fetal cells are in the form of villi
156Placental Endocrinology significant gaps remain in our understanding of the source of these hormones, that is, precisely what contribution is made the the corpora lutea versus the fetoplacental unit.corpora lutea appear to be the exclusive source of progesterone in the bitch. Luteal secretion of progesterone is, in turn, dependent on secretion of luteinizing hormone and probably prolactin from the anterior pituitary.
157Maintenance of Pregnancy in cats elevation of progesterone in pregnancy reflects placental synthesis or enhanced luteal synthesis. Apparently, the ovaries can be removed after about day 45 in cats without interupting the pregnancy, which might suggest that the placenta can indeed synthesize progesterone.
158Both dogs and cats produce the hormone relaxin during pregnancy Both dogs and cats produce the hormone relaxin during pregnancy. In pregnant bitches, relaxin is first detected in serum about 4 weeks into gestation, and increases substantially during the remainder of gestation. The placenta is known to be the primary site of secretion of relaxin in dog
159Fertilization and Early Embryonic Development The union of two haploid gametesthe one-cell embryo rapidly cleaves into 2, 4, 8 and moredevelop a discrete inside and an outsidestart to secrete hormones that ensure their survival - a process called maternal recognition of pregnancy
160sperm must overcome a series of barriers, each of which eliminates a substantial proportion of the original population of spermThe cervix connects the vagina to the uterus. The cervical canal follows an irregular, tortuous route, and the epithelium contains many deep cryptsendowed with mucus-secreting cells, and, as a consequence, the lumen is filled with mucus
161The consistency and viscosity of cervical mucus is under endocrine control When estrogen levels are high and progesterone levels low, as occurs prior to ovulation, cervical mucus becomes watery and its mucin strands assume a parallel orientation. This state apparently greatly facilitates passage of sperm through the cervical canal
162Studies in several species have shown that sperm are able to get from the distal uterus to the oviducts in times as short as a few minutes while eggs remain for three dayssperm transport in the uterus is largely a result of uterine contractionsIn other cases, sperm can remain viable in the uterus for several days
163The uterotubal junction is the region joining the tip of the uterine horn to the oviduct. The morphology of this region varies considerably among species, and and this structure appears to be a significant barrier to sperm especially in animals like rodents and pigs where huge numbers of sperm are deposited directly in the lumen of the uterus.
164Egg TransportThe oviduct provides the appropriate environment not only for fertilization, but for early embryonic developmentThe embryo remain there for a period of about three daysThe highest probability of becoming pregnant was seen when breeding occurred during the two days preceeding
165Cleavage and Blastocyst Formation The product of fertilization is a one-cell embryo with a diploid complement of chromosomesformation of a hollow sphere of cells known as a blastocystthe embryo moves out of the oviduct, into the lumen of the uterus.
166Unfertilized oocytesfour cell embryo is shown here. The cells in cleavage stage embryos are known as blastomeressignals formation of theblastocystthe blastocyst then undergoesimplantation in the uterine wall
167Implantation= Nidation Embryo wandersfreely before nidation
168, the image to the left shows an expanded blastocyst from a dog , the image to the left shows an expanded blastocyst from a dog. This embryo was stained to accentuate the trophoblast and inner cell mass.
170Maternal Recognition of Pregnancy it is a process in which some type of signal prevents luteal regression, allowing the corpus luteum to persist and continue to secrete progesterone. This concept can be illustrated by looking at blood progesterone concentrations over time in a cycling sheep that becomes pregnant.
171Early Embryonic Death 10% EED in mares 15-30% EED in cattle and sows Occurs in the first 30 daysClients see it as a “return to heat” assuming that that female did not conceiveGenetic abnormalities account for a majority of EED
172Although the end result is the same, several different mechanisms for maternal recognition of pregnancy have evolved in different groups of mammals. Some of this diversity can be appreciated by looking at humans, cows and dogsBlastocysts of humans and other primates secrete large quantities of a protein hormone called chorionic gonadotropin (CG), which is very similar to luteinizing hormone. CG binds to luteinizing hormone receptors in the corpus luteum and stimulates continued secretion of progesterone. It may also block signals in the corpus luteum that cause luteal regression.
173In cattle and other ruminants, the corpus luteum regresses at the end of the non-pregnant cycle as a result of secretion by the endometrium of prostaglandin F2-alpha (PGF). The early ruminant embryo secretes copious quantities of a protein called interferon tau. Exposure of the endometrium to this hormone dampens the secretion of PGF, thereby blocking the signal for luteolysis. As a result, the corpus luteum survives and progesterone levels are maintained.
174Colorado State University Dogs do not have multiple, sequential cycles like women or cows. Rather, they have a single cycle roughly every 4 to 6 months. Following ovulation, the pattern of progesterone secretion is essentially the same regardless of whether the bitch is pregnant or not. Consequently, dogs do not have a need for maternal recognition of pregnancy and apparently no mechanism for this process.Last updated on December 16, 2000Author: R. BowenColorado State University
175Adhesion/ attachmentImplantation is the first stage in development of the placenta. In most cases, implantation is preceeded by a close interaction of embryonic trophoblast and endometrial epithelial cells that is known as adhesion or attachment. Nidation occurs at 7 daysattachment involves a tight intertwining of microvilli on the maternal and embryonic cells. Following attachment, the blastocyst is no longer easily flushed from the lumen of the uterus. In species that carry multiple offspring, attachment is preceeded by a remarkably even spacing of embryos through the uterus
176effect of implantation in all cases is to obtain very close apposition between embryonic and maternal tissueshowever, substantial differences among species in the process of implantation, particularly with regard to "invasiveness," or how much the embryo erodes into maternal tissue
177implantation in humans involves the embryo eroding deeply into the substance of the uterus Horses and Pigs have a similar attachment
180Centric: the embryo expands to a large size before implantation, then remains in the center of the uterus. Examples include carnivores, ruminants, horses, and pigsEccentric: The blastocyst is small and implants within the endometrium on the side of the uterus Examples include rats and mice.Interstitial: The blastocyst is small and erodes through endometrial epithelium into subepithelial connective tissue. Examples include primates, including humans, and guinea pigs.
181In some species Estrogen and Progesterone are required for Implanation, species having highly invasive embryos have systems for prenatal transfer of antibodies from the mother to the fetus.
182Monotremes and marsupials In some species, progesterone alone appears to be adequate, while in others, estrogen and progesterone are required for implantation.All mammals except monotremes and marsupials which unlike monotremes areborn only about one month after mating. They emerge from the womb no larger than the size of a cherry and immediately climb into the mother's pouch to nurse
185Placental Structure and Classification The gross shape of the placenta and the distribution of contact sites between fetal membranes and endometrium.The number of layers of tissue between maternal and fetal vascular systems.
186Diffuse: Almost the entire surface of the allantochorion is involved in formation of the placenta. Seen in horses and pigs.Cotyledonary: Multiple, discrete areas of attachment called cotyledons are formed by interaction of patches of allantochorion with endometrium. The fetal portions of this type of placenta are called cotyledons, the maternal contact sites (caruncles), and the cotyledon-caruncle complex a placentome. This type of placentation is observed in ruminants.
187Discoid: A single placenta is formed and is discoid in shape Discoid: A single placenta is formed and is discoid in shape. Seen in primates and rodents.Zonary: The placenta takes the form of a complete or incomplete band of tissue surrounding the fetus. Seen in carnivores like dogs and cats, seals, bears and elephants
192Summary of Species Differences in Placental Architecture Common ExamplesHorses and pigsRuminants (cattle, sheep, goats, deer)Carnivores (dog, cat, ferret)Humans, apes, monkeys and rodentsType of PlacentaDiffuse, epitheliochorialCotyledonary, epitheliochorialZonary, endotheliochorialDiscoid, hemochorial
195Beginning on days 36 to 38 of gestation , blastocyst cells begin to destroy underlying endometrium. In this process they denude surface endometrial epithelial cells and migrate down into endometrial glands, eventually breaking through the basement membrane and invading into the underlying tissue. Within 2 to 3 days after entering the uterine tissue, they round up and differentiate into mature eCG-secreting endometrial cup cells.
196Endometrial cupsAt about 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).
197Equine endometrial cups The images below show endometrial cups (EC) at three stages of gestation. In the rightmost image, umbilical vessels are seen at the bottom.
198This response is initially seen as A. accumulation of Tlymphocytes at the peripheryof the cups, and progresses toa massive accumulation ofT cells, B cells, macrophagessurrounding the cups.B. After day 70 to 80, these leukocytes begin to invade / destroy the cup (the time of this event varies significantly among mares, but usually occurs between days 100 and 140).
199It turns out that eCG is actually equine luteinizing hormone, and is encoded by the same gene responsible for pituitary LH. In contrast to LH from most other species, equine LH/eCG possesses considerable follicle stimulating hormone-like bioactivity.
200Hormones from the Equine Placenta The high blood levels of eCG during this time stimulate development of ovarian follicles. These follicles ovulate or luteinize, resulting in development of so-called secondary and accessory corpora lutea. In concert with the primary corpus luteum, these structures secrete sufficient progesterone to maintain pregnancy until placental progerone synthesis is adequate.
201Hormones produced by the Equine Placenta Progestins: The equine placenta maintains pregnancy.Toward the end of gestation, blood levels of these progestins are typically 100 times the maximal level of progesterone.The placenta maintains pregnancy without any ovarian input of hormones
202Hormones from the Equine placenta Estrogens: In has been known for many decades that mare urine contains high concentrations of estrogens during the second and third trimesters of pregnancy. Indeed, a large industry has developed for collection of pregnant mare urine, which is used to produce Premarin, an estrogen replacement therapy used widely by post-menopausal women.
203Estrogen levels in the serum and urine of pregnant mares begins to rise around day 60 of gestation, peaks at about day 200 then declines during the remainder of gestation.Estrogens are synthesized in the equine placenta from androgens that are produced by the fetal gonads.
204Hormones from the Equine Placenta Relaxin: a hormone that, in various species, is thought to act synergistically with progesterone to maintain pregnancy and to promote loosening of pelvic ligaments at the time of parturition. In horses, relaxin appears to be produced by the fetoplacental unit rather than the corpus luteum. It is detected in mare serum starting at about day 80 of pregnancy, and remains at high levels until term
206Secondary CLsThe secondary CLs result in progesterone rise about day The endometrial cups regress (they are sloughed from the uterus by an immunologic response). ovulatory or anovulatory follicles produce C.L.,s
207The second rise is associated with the formation of accessory and secondary CL. Progesterones rise from mid gestation to term. The fetal placenta produces sufficient progesterone, that ovariectomy can be performed after dprogestins rises (last month of pregnancy)From fetal adrenal glands
208At about 24 hours post ovulation the embyro is at 2 cell stage The Early EmbryoAt about 24 hours post ovulation the embyro is at 2 cell stage4-5 days forming a hollow ball5-6 days blastocyst5-6 days enters uterusCapsule forms around the blastocystProtective coveringOrigin not clearly known - may be embryonic, may have endometrial contributionLost at 21 days