VGO VCRI OND Lecture Notes unit 2.pdf
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1 1. MATERNAL RECOGNITION OF PREGNANCY (MRP) Definition Establishment of pregnancy involves interactions between two interdependent systems defined as: Uterus, and Conce...
1 1. MATERNAL RECOGNITION OF PREGNANCY (MRP) Definition Establishment of pregnancy involves interactions between two interdependent systems defined as: Uterus, and Conceptus (embryo and extra embryonic membranes) At the appropriate time, the conceptus must produce steroid hormones and /or proteins to signal its presence to the maternal system. This signal is necessary for corpus luteum (CL) maintenance, production of progesterone and continued endometrial development and secretory activity. This phenomenon was described by Short (1969) as “Maternal Recognition of Pregnancy” (MRP). In most of the species, the conceptus provide a timely biochemical signal or pregnancy will terminate The critical series of events by which the Conceptus initially signals its presence to the dam and enables the pregnancy to continues is referred as maternal recognition of pregnancy (MRP) MRP must occur prior to luteolysis If the conceptus fails to signal its presence at exactly the correct time, the function of CL is terminated by the luteolytic action of prostaglandin F2 alpha (PGF 2 alpha) from the uterus. This ensures that the female will return to estrus and mate at frequent intervals until a successful pregnancy is established. Uterine PGF 2 alpha is produced by endometrium of cows, ewes, mares and sows and causes morphologic regression of CL and cessation of progesterone production. Non pregnant Pregnant Secretion is however, in an exocrine PGF 2 alpha is released in an endocrine direction during pregnancy and direction during estrus cycle (non pregnant) to PGF 2alpha is, therefore, unable to exert its cause regression of CL. luteolytic effect on the CL. The effect of conceptus is luteostatic, since progesterone production is maintained at a level comparable to that of dioestrus during pregnancy. 2 Basal secretion of luteinizing hormone (LH) from the anterior pituitary is also essential for CL maintenance and function during pregnancy. Interferon from the Conceptus prevents luteolysis in the cow and Ewe Interferon tau produced from trophoblastic cells Endometrial cells of the uterus Inhibits the production of oxytocin receptors Oxytocin cannot stimulate Prostaglandin synthesis. Interferon tau also causes production of proteins from the uterine glands which migrates to uterine lumen to nourish the Conceptus Estradiol reroutes PGF 2 α to prevent luteolysis in Sow In the non pregnant sow, oxytocin from the endometrium, posterior pituitary lobe and CL promotes PGF 2α synthesis by the uterine endometrium. PGF 2α diffuses by concentration gradient towards the endometrial capillaries where it drains in to the uterine vein, is transported to the ovary and cause luteolysis. 3 In the pregnant sow, the blastocyst produces estradiol that causes the PGF2α to be rerouted into the uterine lumen, where it is destroyed, thus preventing luteolysis. Like the cycling cow, oxytocin is also produced by the CL and posterior pituitary lobe in the pregnant sow Another important feature of MRP in sow is that there must be at least two conceptuses present in each uterine horn for pregnancy to be maintained. Of conceptuses are not present in one uterine horn, PGF2α will be secreted in an endocrine fashion, luteolysis will occur and the pregnancy will not be established Transuterine Migration of Equine conceptus In the mare, the presence of conceptus prevents luteolysis. Also in the presence of conceptus, endometrial production of PGF2α is significantly reduced. A unique feature of MRP in the mare is that conceptus must migrate within the uterus from one uterine horn to the other. This migration must occur between 12 and 14 times per day during days 12, 13 and 14 of pregnancy in order to inhibit PGF2α. The intra uterine migration of the equine conceptus appears necessary because the conceptus does not elongate as in other species. Therefore, there is less contact between the conceptus and the endometrial surface. In other words, th e migration of the conceptus is probably necessary to distribute pregnancy recognition factors to the endometrial cells. Like other species, the conceptus of the horse produces proteins that apparently have some effect on the recognition of pregnancy. Each Black sphere represents a stopping spot in which the conceptus will spend between 5 and 20 minutes. The migration of the conceptus probably distributes pregnancy factors over a wide surface of the endometrium MRP in dog and cat probably does not require a signal from the conceptus In the bitch, the CL of pregnancy and the CL of the cycle have similar life spans. Therefore, under normal cyclic conditions, the CL is long lived. When luteolysis does occur it is near the end of the normal gestation period. In other words, the period of diestrum is quite similar to gestation period and thus the CL is not lysed under normal conditions until the gestation period is complete. The queen is an induced ovulator. If mating does not occur, CL is not formed and a post estrous period of several days (8-10) exists before another estrus. In the queen which has bred, a CL forms and the duration is same as gestation of around 60 days. Similar to bitch, a signal from the conceptus is not needed because the CL is lysed before a pregnancy is established. 4 Maternal Pregnancy recognition factors, critical days of pregnancy and time of conceptus attachment in mammals Critical period of Time of S No Species MRP factors recognition (Days Attachment (days after ovulation) after ovulation) 1 Cow Bovine interferon tau 15-16 18-22 2 Ewe Ovine Interferon Tau 13-14 15-18 3 Sow Estradiol 11-12 14-18 4 Mare Proteins/estrogens? 12-14 36-38 Bitch & 5 None needed - - Queen 6 Woman hCG 7-12 9-12 5 2. PLACENTATION It is a unique organ that develops in mammalians for the development of the fetus. It is an apposition of fetal membranes to the endometrium to permit physiological exchange between the fetus and the mother. The placenta is composed of two parts: 1. The fetal placenta or allantois chorion 2. The maternal placenta or endometrium. The yolk sac or amniotic chorion acts as primitive placenta for a few weeks in the early embryonic period. Allantois develop as a diverticulum of hind gut and fuses with the chorion (trophoblastic capsule of the blastocyst) to form the chorioallantoic placenta. The blastocyst gets attached to the endometrium and the fetal membranes including the allantois chorion develop during the first month or more of gestation. At this time, the villiform projections of the chorion and the maternal crypts in the endometrium are rudimentary, small and friable, and the nutrition is from the uterine secretions. Non-Rejection of Placenta in Pregnant Animals In hemochorial placentas (man and rodents), greater the trophoblastic invasiveness, the greater the necrosis of both chorionic and endometrial tissue thus resulting in development and deposition of a mechanical acellular barrier of acid mucopolysaccharide In epitheliochorial placentas, (cow, sheep, mare and sow) where the interdigitation of microvilli of the chorion or trophoblast and endometrial epithelium are closely apposed, no extensive degeneration or deposition of fibrinoid is present. Therefore, in the former (hemochorial placentas) an acellular mechanical barrier and in the latter (epitheliochorial placentas), the absence of trophoblastic antigenecity offer reasonable explanations for the retention of the placental homograft. The sire contributes half of the genetic makeup of the fetus and placenta and hence there should be sufficient tissue incompatibility to induce an immune reaction in the dam and subsequent rejection of the conceptus. The inability of the immunologically active maternal cells to penetrate in to fetal circulation may also be important. CLASSIFICATION OF PLACENTA Placentas are classified according to 1. Chorionic villi distribution/ Anatomical 2. Based on the separation between fetal and maternal blood supplies/ Microscopic 3. Degree of contact between chorionic villi and the endometrium 1. Anatomical classification/ chorionic villi distribution It is divided in to 4 general types based on their shape as: Diffuse Cotyledonary Zonary Discoidal 6 Diffuse The diffuse placenta of the sow consists of numerous chorionic villi on surface of chorion. They penetrate into endometrium forming feto- maternal interface The diffuse placenta of the mare has many micro-cotyledons on the surface of the chorion, which are responsible for fetal-maternal exchange. The mare placenta is characterised by having numerous specialized microzones of chorionic villi known as microcotyledons. These are the discrete regions at fetal maternal interface. Mare placenta also contains transitory structures known as endometrial cups. It is of both endometrial and trophoblastic origin. There were 5-10 endometrial cups distributed over the surface of the placenta which secrete equine chorionic gonadotropin (eCG). And develop between days 35-60 of pregnancy. Following day 6o the endometrial cups are sloughed into uterine lumen and no longer functional. Cotyledonary Ruminants have cotyledonary placenta. A cotyledon is defined as placental unit of trophoblastic origin consisting of abundant blood vessels and connective tissue. In sheep there are between 90-100 cotyledons distributed across the surface of the chorion and in cattle around 70-120 cotyledons have been observed. The placentome (point of interface) In the cotyledonary placenta consist of fetal cotyledon contributed by chorion and a maternal cotyledon originating from the caruncular regions of the uterus. At about day 16 in sheep and day 25 in cow the chorion initiates attachment to the caruncles of the uterus. Prior to this time the placenta is essentially diffuse. During the formation of placentome, chorionic villi protrude into crypts in the caruncular tissue. Attachment is well established by day 30 in ewes and day 40 in cows. Cotyledonary placentas are char by button like structures on the surface of the chorion. They are referred as fetal cotyledons. They join with maternal caruncle and form a placentome A convex cotyledon becomes covered with chorion. Many finger like villi originating from the chorionic tissue protrude toward the lumen of the uterus. In the concave cotyledon, the chorionic tissues push inward, forming a concave interface between the chorion and maternal caruncle. 7 Zonary A-Allantois; AC-Allantochorion; AM-Amniotic cavity; E-Endometrium; M-Myometrium; Ys-Yolksac The zonary placenta includes a prominent region of exchange that forms a broad zone around the chorion near the middle of the conceptus. A second region consists of highly pigmented ring at either end of the central zone. The pigmented zone consists of small hematomas. The pigmented zone is also referred as paraplacenta and is thought to be important in iron transport from the dam to fetus. The function of this zone is not well understood. A third region is the transparent zone on the distal ends of the chorion that has poor vascularity. This zone may be involved in absorption of materials directly from the uterine lumen Discoidal A-Allantois; AC-Allantochorion; AM-Amniotic cavity; E-Endometrium; M-Myometrium; EZ- Exchange Zone The discoid placenta is found in rodents and primates. It is characterised by having one or two distinct adjacent discs. These discs contain chorionic villi that interface with endometrium and provide the region for nutrient and metabolic waste exchange 8 2. Classification based on separation between fetal and maternal blood supplies The nomenclature for describing placental intimacy is derived by describing the tissues of the maternal placenta in prefix of the word. The tissues of the fetal placenta constitute the suffix. Exchange can occur through as many as six layers and as few as three. Prefix = maternal side suffix = fetal side Epithelio chorial Epitheliochorial Epitheliochorial placenta In this type, both the endometrial epithelium (maternal side) and epithelium of the chorionic villi are intact. There is complete intact layer of epithelium in both maternal and fetal components. Found in sow and mare; Ruminants are also having epitheliochorial placenta. However the endometrial epithelium transiently erodes and then regrows causing intermittent exposure of maternal capillaries to the chorionic epithelium and it has been termed as syndesmochorial Pig, horses and ruminants 6.Chorionic capillaries 5. Chorionic interstitium 4. Chorionic epithelium 3. Endometrial epithelium 2. Endometrial interstitium 1. Endometrial capillaries In addition to feature of partial erosion of the endometrial epithelium, a unique cell type is found in the ruminant placenta. These cells are called nucleate giant cells. They are characterised by quite large and have two nuclei. Binucleate giant cells appear at about day 14 in sheep and between day 18 and 20 in the cow. Binucleate giant cells (BNGC) migrate from the chorion to the endometrial epithelium in ruminants. These cells are thought to secrete placental lactogen and pregnancy specific protein B (PSPB) These cells originate from trophoblast cells and are believed to be formed continuously throughout gestation. Binucleate giant cells constitute around 20 % of the fetal placenta. During development, the binucleate giant cells migrate from the chorionic epithelium and invade the endometrial epithelium. These cells are believed to transfer complex molecules from the fetal to maternal placenta. There is evidence that they secrete placental lactogen and pregnancy specific protein B (PSPB) that are called pregnancy associated glycoproteins. These proteins are unique to pregnancy in ruminants. These 9 binucleate cells are important sites for steroidogenesis producing progesterone and estrogen. Endothelial chorial It is characterised by having complete erosion of the endometrial epithelium and underlying interstitium. Thus maternal capillaries are exposed to epithelial cells of the chorion Dogs and cats 5. Chorionic capillaries 4. Chorionic interstitium 3. Chorionic epithelium 2. Endometrial interstitium 1. Endometrial capillaries Haemochorial The haemochorial palcenta is characterised by having chorionic epithelium in direct apposisition to maternal pools of blood. Thus, nutrients and gases are exchanged directly from maternal blood and must move through only tissue layers. This highly intimate relationship is found in primates and rodents 3. Chorionic capillaries 2. Chorionic interstitium 1. Chorionic epithelium RBC- Red blood cell 3. Degree of contact between chorionic villi and the endometrium Deciduate or conjoined or placenta vera Seen in man and rodents and in a slightly modified form in the dog and cat. In this type, the decidua composed of portions of the maternal epithelium or endothelium, submucosa, decidual cells and the fetal placenta are shed at parturition leaving the portion of the endometrium denuded. Indeciduate or adeciduate Seen in swine, horses and ruminants. In this type, the fetal membranes and placenta are expelled at the time of parturition, leaving the endometrium intact except in ruminants in which only the surfaces of the carcuncles are devoid of epithelium after the caruncles sloughs about 6–10 days following parturition. 10 ADVENTITIOUS PLACENTA The endometrium between the caruncles is called inter-caruncular endometrium and the fetal placenta between the cotyledons is called the inter-cotyledonary placenta. This area normally does not take part in placental functions once the placentomes are formed. Sometime, because of uterine disease or lack of placentomes, primitive p lacental structures simulating a diffuse placenta which develops in this area between allantois chorion and the endometrium. These are called adventitious placenta or accessory placentomes Normal placenta with fetal cotyledons Adventitious placenta(Extensive) with absence of cotyledons AMNIOTIC PLAQUES Most noticeable during 3-7 month of gestation. Number varies widely and consists of edematous epithelial cells that are sometimes keratinized. Amniotic proliferations are found to a lesser degree in horses, sheep and goats but not in swine and carnivores. Etiology and significance is not known and they are apparently not due to infectious agents either bacterial or viral and there are no inflammatory lesions associated with these plaques. These plaques are localized squamous proliferations called verrucae HIPPOMANES The cow, horse, sheep, goat and pig allantoic fluid contains amorphous, semisolid, amber coloured, soft, pliable, rubber like, irregular shaped masses or bodies, thinner at the edges and thicker in the center 2.5–15.0 cm in diameter and from 0.3–3.8 cm in thickness floating in the fluid. These bodies are called as Hippomanes. These are referred to as “Allantoic Calculi”. CERVICAL STAR Cervical star reflects the contact area between the cervical folds and the chorion. The epithelium of the cervix lacks the crypts to connect with the villi of the chorion. Its an irregular bare spot in the diffuse placenta of the chorion is found over the internal os of the cervix 11 Cervical star The placenta of the mare produces a gonadotropin called Equine chorionic gonadotropin (eCG) or Pregnant Mare Serum Gonadotropin (PMSG). eCG is produced by endometrial cups which is the transient endocrine gland of the placenta. They begin to produce eCG at the attachment of conceptus. eCG acts as a luteotropin and provides stimulation for maintenance of primary CL (CL from ovulated follicle). In addition, eCG is responsible for controlling the formation and maintenance of accessory CL which usually occurs at days 40-70 of pregnancy. In addition to luteotrophic action, eCG has more potent FSH like actions and commonly used in superovulation when embryo transfer is performed (cow, Sheep, rabbit). In mare, eCG does not exert FSH like actions. P4 from the primary CL increases rapidly Upon stimulation by eCG, the primary CL is after ovulation and decreases (hatched stimulated and P4 in maternal blood region). Without eCG P4 would decrease increases. If eCG were not produced, P4 (dashed region) and pregnancy would would continue to decrease terminate As eCG continues to increase, accessory CL develops and P4 increases until day 100. After that, the placenta takes charge for major P4 production Mare can have problems with twins. Must get rid of one before Day 30 or if both are lost after Day 30 endometrial cups will have formed. Cannot rebreed until another 60 to 90 Days when cups are shed. Similar problem with a mare which aborts after Day 30 Another important gonadotropin of placental origin is human chorionic gonadotropin (hCG). It is not only found in human but also in many primates. It originates from the trophoblastic cells of the chorion and is secreted as soon as the blastocyst hatches from the zona 12 pellucida. hCG can be detected in blood as early as day 8 to 10 of gestation. It rapidly increases in the urine of woman reaches maximum value at about 2.5 months. The primary role is to provide a luteotrophic stimulus for the ovulatory corpous luteum as it transitions into the CL of pregnancy. hCG is commonly used to induce ovulation (LH effect) in superovulation protocols. The placenta produces hormones that can Stimulate ovarian function Maintain pregnancy Iinfleunce fetal growth Stimulate mammary function Assist in parturition Placental hormones includes Progesterone PMSG hCG Relaxin Placental lactogen Pregnancy specific protein B / PAG Prostaglandins Placenta produces P4 which provides stimulus endometrial glands for elevated secretion. High P4 is also responsible for the so called progesterone block that inhibits myometrial contraction. Sources of Progesterone during Gestation S no Species Progesterone source Gestation CL Up to day 50 then placenta 1 Sheep 150 days Can remove CL after day 50 will not cause abortion CL and Accessory CL together support P4 till day 2 Mare 100. 330 days After day 100, Placenta assumes P4 production CL throughout. However, after ~ day 215 placenta 3 Cow and adrenal produce 280 days enough progesterone to maintain pregnancy Throughout from CL Remove CL at any time 4 Sow 114 days causes abortion 13 In addition to progesterone, estrogens are also secreted by the placenta, particularly during the last part of gestation. The peak estrogen in most species signals early preparturient period. Placental lactogen is Protein hormone - 192 AA; 22,000 and 23,000 daltons; Important for its GH like properties; Regulation of maternal nutrients and fetal growth. It has been hypothesized that, sire can influence the fetal placental lactogen and enhance milk production. Pregnancy specific protein Prevents destruction of CL; First reliable hormonal pregnancy test Placental relaxin is produced in Mares, cats, Bitches, sows, rabbit, monkeys and humans. In rabbit the relaxin is produced completely from the placenta and not from the ovary. Relaxin is not present in bovine placenta during any stage of gestatio n a possible exception is that ovaricetomy does not result in calving difficulties. It is likely that relaxin is produced from ovary and placenta except in rabbits. Placental function includes exchange of nutrients and metabolite between dam and fetus Fetus synthesizes proteins from maternal AA. Lipids do not cross placenta- Placenta hydrolyses triglycerides and maternal phospholipids- new lipid materials are synthesized Large peptide hormones- TSH, ACTH, Growth hormone, insulin- do not cross placenta Fat soluble vitamins- cross with difficulty, Water soluble vitamins-cross with ease Viruses – cross with ease: Herpes, HIV Simple diffusion Gases and Water pass from high to low concentration Facilitated diffusion Glucose and aa are transported using specific carrier molecules Active transport Active transport pumps for Na, K and Ca 14 3. ABORTION Definition Abortion: expulsion from the uterus of a living fetus before it reaches a viable age or more commonly the expulsion of dead fetus of recognizable size at any stage of gestation Expulsion of dead or live recognizable size fetus at any stage of gestation (45 -60 days onwards to parturition) Premature birth: Expulsion of weak and viable fetus 15-20 days or 30 days early to the expected date of parturition and it may die shortly after birth Still birth: Expulsion of a dead fetus at the time of parturition especially in swines Habitual abortion: repeated abortions at a particular month of gestation in the same animal Threatened abortion: At any stage of gestation, that animal may show the symptoms of abortion but need not abort Early embryonic death: unseen expulsion of the ova, embryos or foetuses is called early embryonic death In a cow abortions occurring after fourth month of pregnancy are characterised by retention of placenta; but abortions occur before fifth month are seldom followed by retention of placenta; abortions are usually caused b agents affecting the fetus or fetal membranes or both. Economically the abortions are of great concern to the farmer because, Fetus is lost Prolonged period of uterine disease and infertility may follow Maintenance of unproductive animal If infectious, it may threatens the rest of herd Diseases of the fetus and pregnant uterus do not always result in fetal death. The fetus may expelled prematurely or at term and live or it may be weak and diseased and die shortly after borth. In most abortions the fetus dies in the uterus and expelled within 24-72 hrs with various degree of post-mortem changes as follows. Fetal death (in hrs) Autolytic changes 12 hrs Fetal corneas are cloudy and grey Kidneys are soft and the abomasal contents are cloudy, mucoid and 24 hrs yellow Colour changes in skin, subcutis is gelatinous and blood tinged, liver 36-96 hrs is soft, abomasal contents are cloudy, mucoid and reddish 15 Abortion in Bovines In cattle herd, an incidence of abortion of more than 2-5 % should be viewed seriously and efforts are made to determine the cause and control measure to be initi ated. Unfortunately 20-25 % of abortions are only yield a definite diagnosis of causative agents. A single serological test is often of questionable value. Serological testing of aborting cows at the time of abortion and 2-3 weeks later may helpful by the rise in titre value for certain infectious agent between first and second samples The various agents causing abortion are broadly classified as Infectious and non infectious causes Infectious causes Bacterial : Brucellosis – Br. abortus Leptospirosis – L. pomona Listeriosis – L. monocytogenes Vibriosis – V. Fetus & V.venerealis Tuberculosis – Mycobacterium bovis Viral : Infectious bovine rhinotrachitis - infectious pustular vulvo vaginitis (IBR–IPV) Epizootic bovine abortion (EBA or Chlamydia) and Miscellaneous viruses Mycotic or fungal : Aspergillus and Mucorales species Protozoal : Trichomoniasis Non infectious causes Physical : Douching, Infusion or AI of the pregnant animals Chemical, Drug and : Nitrates, chlorinated napthalenes, arsenic, locoweeds, perennial broom poisonous plants, weed, pine needles Genetic or Chromosomal : Certain defects of the embryo or fetus Nutritional : Starvation, malnutrition, Vitamin A deficiency, Iodine deficiency 16 Hormonal : Estrogen, glycocorticoids, progesterone deficiency Miscellaneous : Twinning, allergic and anaphylactic reactions, tumors etc 1. Brucellois – Bangs Disease or Contagious or Infectious abortion First described by Bang in 1897 in Denmark. Causative organism Brucella abortus Morphology Small gram negative, rod shaped intracellular organism Route of infection 1. By ingestion of infected materials (uterine discharge, fetal membrane and utensils) 2. Penetration through abraded skin 3. Mucus membrane of the eye 4. Artificial insemination with infected semen (usually not– transmitted by natural service) Time of abortion Last trimester of pregnancy Zoonotic importance Highly contagious disease produce undulant fever or brucellosis in man Resistance Easily destroyed by simple detergent or disinfectants, sunlight, drying, putrefaction and pasteurization. Site of predilection Chorion of the placenta. After 1–5 months of abortion it disappears in the uterus. Apparently it grows well only in the feal placenta because of the presence of a chemical “Erythritol” which is highly essential for the growth of the organism. Adult cow: Udder, lymph nodes (Supermammary, retropharyngeal and internal and external iliac lymph nodes) and joints Adult male: Testes, epididymis, vasa deferentia and seminal vesciles. Lesion Pre monitory signs: Udder enlargement, vulvar edema Edematous, hemorrhagic, leathery foetal membranes with necrotic, brownish yellow, pasty exudates in the utero chorionic space. Sequelae Retained placenta, metritis and infertility Diagnosis 1. History: Any storm of abortion in a herd during the 3 rd stage of gestation brucellosis may be suspected. 2. Isolation of the organism in culture media or guinea pigs: Materials collected for isolation from fetus: Lungs, stomach or placenta 3. Serological tests: i. Agglutination test 17 a. Tube agglutination b. Plate agglutination ii. Heat inactivation test iii. Acidified plate antigen test (APA) iv. Acridine compound precipitation test (Rivanol) v. Complement fixation test (CFT) vi. 2–Mercaptolethanol test (ME) Among the above serological tests, the tube and the rapid plate agglutination tests are the routine official test performed to identify the infected cattle in a problem herds. In non vaccinated cows: 1:50 reaction is a suspicious reaction, 1:100 is positive In vaccinated cows: 1:100 reaction is a suspicious reaction 1:200 is positive Recently the card test is employed as a rapid, sensitive accurate test for field screening of brucellosis. 4. Agglutination tests on milk: i. Milk ring test (MRT or the Brucellosis Ring Test (BRT)) ii. Whey agglutination test As a hard screening procedure the M.R.T is highly effective in screening the herd. 5. Agglutination test on seminal plasma: It is highly effective in detecting affected bulls. Control Hygiene or sanitation: Aborted fetuses and placentas should be buried or burned and contaminated areas should be disinfected. Isolation: Infected animals and new corners should be isolated for four weeks and retest before placing with the herd or chronically infected animals should be sold or slaughtered. Vaccination: Vaccination of calves from 3 to 7 months of age with 5 ml of freeze dried refrigerated, stabilized, low virulent strain 19 brucella vaccine subcutaneously immediately after reconstitution produces a rapid rise in serum antibody titre before thirty months of age. Because of persisting titers in older calves, vaccinating calves at 3 to 6 months of age is ideal. The titer produced in these younger calves usually disappears by 18 18 months of age. Vaccination of cattle over 8 months of age tends to cause persistent blood titers and in pregnant cows may occasionally cause abortion. Bull calves should not be vaccinated as strain 19 rarely localizes in their genital tract or a persistent serum titer may occasionally develop. Treatment Treatment for brucellosis, including a variety of antiseptics and antibiotics has been attempted in cattle but with no success. 2. Leptospriosis Dunghill well’s disease, Stuttgart disease. Leptospirosis was first described in cattle in the U.S. in 1944 by Jungherr. Causative organism L. pomona, L. hardjo, L. grippotyphosa, L. canicola Morphology Small filamentous spirochete Found in all species of domestic animals including dogs and cats but are most wide spread in ovine and cattle Route of infection i) Penetration through abraded skin of the feet and legs. ii) Passing through the mucus membrane of mouth, pharynx, nose and eyes by contact with infected feed or urine. Infected bulls can shed the organism in semen for a month or more and transmitted by coitus also. Time of abortion Last half of gestation. 1 – 3 weeks after recovery from the acute febrile stage Zoonotic importance affects man after swimming in the infected water, abattoir and dairy workers Resistance Easily destroyed by heat, sun light, drying, acid and chemical disinfectants Site of predilection Tubules of the kidney and the organisms are shed in the urine, for 2 – 3 months and also shed in milk Foetus: liver & kidney. It is not isolated in the foetus because death of the organism takes place due to autolytic changes since expulsion takes some days after death of the foetus. Eradication Leptospirosis is not amenable for eradiction because wide spread occurrence of several serotypes (about 40 serotypes) in many wild and domestic animals and because of the carrier animals. 19 Species variation Though it is found in all species of domestic animals including dogs and cats it is the most wide spread organism in swine and cattle. Swine may shed organisms in the urine after infection should not be side by side or atleast the piggery waste should not pass through the dairy farm. Clinical signs Elevation of body temperature (103 – 107°F) Anorexia, Drop in milk flow with a slack udder containing slightly thick gargety milk. Anemia, haemoglobinuria, dyspnea, icterus and often death in one to three days in severe form of the disease. Lesion Widespread petechia Incubation 3–7 days. Abortions occurred 18–19 days from the initial infection because of two consecutive infections in the dam and fetus to complete their courses. Sequelae Retained fetal membranes, metritis and infertility Diagnosis More difficult than those due to brucellosis 1. Clinical symptoms 2. Necropsy findings 3. Fluorescent antibody technique 4. Serological test i. Rapid macroscopic plate agglutination test ii. Microscopic agglutination test iii. Stoenner’s capillary tube test iv. Milk agglutination test Two serum samples are taken about 2–3 weeks apart to show a strongly rising leptospiral tittre (at the time of acute illness and then at the time of or shortly after abortion) Control i. Isolation of newly purchased animals ii. Hygiene and sanitation iii. Vaccination and antibiotic therapy Living avirulent or attenuated vaccines have been proven satisfactory experimentally but not for commercial use. Bacterius are widely used and provide an excellent immunity for 6– 12 months; hence cattle are vaccinated twice yearly. Pregnant cows can be vaccinated. iv. Protected water supply v. By preventing ingestion of contaminated feed, exposure to infected urine and semen 20 Treatment 25 mg of dihydro Streptomycin per kg of body weight as a single intramuscular injection (8 to 15 gm). Penicillin – 3 million units or Streptomycin – 5gm twice daily. Tetracycline 2.5 to 5 gm, daily for 5 days. In case of hemoglobinuria and anemia, blood transfusion and supportive therapy may also be indicated 3. Listeriosis Causative Listeria monocytogenes organism Morphology Gram positive, slightly motile red or cocci organism Route of Can penetrate intact mucus membrane of respiratory or infection alimentary tract. It has been found in silage particularly in poor quality silage with high PH. Carrier animals may spread the organism for a long period in their nasal secretions and feces. Sudden change in management or feeding practices inducing stress and lowered resistance are often associated with outbreaks Time of abortion Last trimester without clinical illness (7 th–9th month of gestation) Resistance Can survive even in undesirable climate. Site of Foetus: placentomes, spleen, brain stomach and kidney. predilection It can be found in moist or dry soil, bedding, fecal material and secretions. Eliminated through milk and feces of the infected animals. Listeria may recover from the genital tract for about 10 days after abortion and 25–36 days in the body tissue. Clinical signs Clinical signs are uncommon. However three clinical forms of listeriosis are observed. 1. Septicemic form: Affecting young prenatal and human beings and characterized by the early death of the new born with hepatic lesions, gastroenteritis and meningitis. 2. Reproductive form: Affects mature animals, especially ruminants and swine. 3. Reproductive form: Especially in ruminants and humans characterized by abortion Lesion There are no pathognomnic lesions of listeriosis in aborted 21 foetus and membranes. Pin point small yellow foci of necrosis – liver and spleen autolysis of the foetus takes place, death usually occur 5 days before expulsion. Sequelae Dystocia, retained fetal membranes, metritis and infertility Diagnosis Immunofloresent test, Agglutination test. Treatment Cessation of silage feeding. Antibiotic therapy with large doses of the tetracycline or penicillin and streptomycin for four to five days 4. Vibrosis – Venereal disease of cattle First discovered by Mc Fadyean and Stockman in 1910 and 1913, respectively Causative organism Vibrio foetus venerealis Morphology As motile or non–motile, gram–negative, short, comma, shaped rods are as double spiral–shaped filaments. Route of infection Spread at the time of coitus or at the time of AI. Time of abortion Commonly early embryonic death and occasionally late abortions from 4 months to term. Zoonotic In man it causes undulating fever, placental infection and importance abortion Resistance Highly susceptible to light, drying and other adverse influences. Site of predilection Found only in the female genital tract and its contents, foetus and placenta. In males: Prepuce and semen it has never been found in the deeper tissues of the male reproductive tract. Lesion i) Increased number of NS / AI per conception ii) Estrous mucous may be increased in amount, stringy mucopurulent discharge from vagina–symptoms of endometritis iii) Long estrous cycle Treatment Infusion of one gram of Streptopenicillin in aqueous base. Viral causes of abortion in cattle Infectious bovine rhinotrachitis (red nose) and infectious pustular vulvovaginitis (IBR–IPV) This is a herpes virus which is causing abortion in cattle but other domestic animals are not susceptible to this virus. Though the morbidity vary from 1 0–100 per cent, the mortality is generally under 10 per cent. The varied clinical forms of this disease includes 22 1. The upper respiratory form (red nose) 2. Conjunctival form 3. Neonatal digestive form 4. Meningio encephalitic form 5. Vulvovaginal form (coital vesicular exanthema) 6. Preputial form 7. Prenatal or abortive form 8. Intrauterine form Abortions may occur in all three trimesters of gestation but are most common from mid gestation to term. If the IBR–IPV virus is present in semen at the time of AI, it may cause a necrotizing endometritis. This results in an erect, edematous uterus and a short estrous cycle of 9 to 15 days in length. Abortions may occur from 2 weeks to 2 to 3 months after any form of the disease in pregnant animals but is only rarely observed in the vulvo vaginal form. Signs of impending abortions are usually not observed. Aborted foetuses are invariably expelled dead with a degree of autolysis. Necropsy findings i. The placenta shows autolytic non–distinctive lesions characterised by edema and the presence of a yellow, brown amniotic fluid. ii. Autolysis of the fetus to a varying degree with reddish brown subcutaneous edema and dark red watery fluid in the body cavities. iii. Focal necrosis of the liver, lymph glands, kidneys and placenta. iv. The kidneys are surrounded by a marked hemorrhagic edema which is the most striking gross changes in this disease. A severe hemorrhagic necrosis is confined largely to the cortex and in more severe form, the medulla and part of the cortex are floating in dark fluid. During the acute stage of illness, virus may be recovered from the nasal cavity, the vagina, the conjunctiva and prepuce. Usually within 10–26 days after the acute illness the virus disappears. Diagnosis i. Isolation of the virus (fetal cotyledon) ii. Serological test–serum neutralization test iii. Fluorescent antibody technique IBR–IPV virus like herpes simplex in humans and rhinopneumonitis virus in horses, clinical lesions with multiplication of the virus may develop even when antibiotics are present in the blood stream. Control 23 i. Isolation of new arrivals. ii. Contact between animals should be kept at a minimum during outbreak iii. Breeding should be stopped in vulvovaginal or preputial form iv. Antibiotic treatment to prevent secondary complications. v. Proper disposal of the fetus and its membranes vi. Vaccinations: Pregnant cows at any stage of gestation should not be vaccinated with IBR–IPV vaccine. Vaccination can be carried out in heifers at 6 to 8 months of age. The immunity will last 3 or more years. Epizootic Bovine abortion (E.B.A) It is caused by an agent of the psittacosis lymphogranuloma, Chlamydia or migawanella group of organisms. Though the organisms in the group are considered viruses they differ from most viruses as follows. i. They are susceptible to antibiotics. ii. Grow well in the yolk sac of chick embryos and they have developed cycles during which large elementary bodies are formed. It may occurred mostly in first calf heifers or newly introduced cattle. Abortions may occur during the 6th to 8thmonths of gestation. There is no clinical evidence of infection in the cow. Abortions occur suddenly without premonitory signs of illness or impending abortion. Once a cow aborted, an immunity is apparently produced and only occasionally cow aborts at second time. Aborted foetuses are clean, fresh and pale or anemic and death had apparently occurred during delivery or shortly thereafter because the onset of parturition or abortion prior to the death of the fetus due to the hyperplastic adrenals. Necropsy findings i. Anemia and extensive potechial haemorrhage of the conjunctival oral mucosa and skin. ii. Presence of straw colored fluid in the body cavity. iii. Edematous subcutaneous tissues in the head. iv. Swollen coarsely nodular yellow colored liver v. Enlarged and edematous lymph glands vi. Intercotyledonary tissue of the apices of the placenta are often tough, leathery and reddish white in colour. vii. Treatment: 2gms of chlortetracycline. 24 Mycotic or fungal causes of abortion 1. Aspergillus fumigates 2. Mucorales i. Absedia ii. Mucor iii. Rhizopus Incidence: 0.5 to 16 per cent of all abortions. The incidence of mycotic abortions may be high in the winter months followed a wet summer season. Aspergillus and mucor molds are ubiquitous in nature and are usually saprophytic. Mode of injection: Inhalation – lungs – blood – placenta – fungal placentitis abortion ingestion – ulcers – mycotic rumanitis – interference with the transport of the nutrients – fetal death and abortion. Time of abortion – 5th to 7th month of gestation Since the non gravid uterus is quite resistant, mycotic infections could not be established by the intrauterine infusion of aspergillus fumigates spores at the time of insemination at estrus. Necropsy findings 1. Thick, edematous, leathery and necrotic chorion 2. Large, swollen, edematous and necrotic placentomes 3. In severe form complete detachment placentomes may be noticed. 4. Dully grey center surrounded by areas of hemorrhagic cotyledons are firmly attached to the leathery chorion. 5. Presence of reddish fluid with large, flakes of pus in the utero – chorionic space 6. Appearance of the growth of the mold on the skin in patches or plaques that resemble congenital ichthyosis or ringworm 7. Presence of straw colored serous fluid in the fetal tissues or in the body cavities 8. Swollen liver The mold can be recovered from the stomach contents, chorion or cotyledons of the placenta and from lungs. As like that of chorion the endometrium is also severely affected with fungus without generalized symptoms of septic metritis. Recovery in severe cases may be slow and prolonged or permanent sterility may follow. Diagnosis: Microscopic observation of the mold either from placenta or by culture of the mold in an artificial media. 25 GENERAL CONSIDERATIONS OF ABORTIONS It is important that the appropriate specimens for diagnostic laboratory assistance are properly collected, handled and submitted so that they arrive promptly in good conditions for examination. The best specimens include the aborted fetus and fetal membranes and maternal serum, urine and vaginal discharge. If it is impractical to submit the whole fetus, perform a necropsy and submit the tissues and specimens listed below. Weigh the fetus or estimate the weight and determine the age by crown -rump measurement. For histopathological examination, place 1/2 to 1/2 inch thick sections of tissues and whole cotyledons in 10% buffered neutral formalin (BNF): 10 volumes of BNF to 1 of tissue. Send directly or keep overnight at room temperature. Transfer fixed tissues to a small, wide-mouth, screw-capped jar or sealed plastic bag containing 1 to 2 volumes of fresh BNF. All specimens for microbiological examination should be placed in separate small containers, eg. Whirl bags, then placed together in a larger container, and packed with enough ice, insulation, and packing to provide refrigeration and to prevent leakage until arrival at the diagnostic laboratory. Specimens should be forwarded to the laboratory without delay. Preferably have someone take the fetus or specimens directly to the laboratory. As the time interval between collections and laboratory examination increases, chances for diagnosis diminish. Origin Fresh or refrigerated 10% BNF Fetal 2-3 infected cotyledons and 2-3 infected cotyledons membranes surroundingICA Abomasal contents 3-5 ml Lung, Liver, Kidney, Intestine Lung, Liver, Kidney - 1/2 to 1/2 Fetus and other organs with Spleen, blood sample or lesions. peritoneal or pleural fluid - 5 ml Serum 4-5 ml* Aborting cow Vaginal discharge or cervical - swab, Urine: 3-5ml Serum sample from 10 cows or In contact cows - 10% of the herd* 26 Chemical, drugs and poisonous plants Chemicals Nitrate (low land or mashland abortion) 1. Cattle pastured on plants which is having high content of nitrate. 2. Accidentally feeding of fertilizers. Abortion occurred from 3 rd to 9th months of gestation Chlorinated napthalenes Normally produce hyperkeratosis or X disease and an acute vitamin A deficiency characterized by dry, thick wrinkled skin, metaplasia of the epithelium, metritis, abortion, dystocia and retained placenta. Other chemicals which causes abortion are i. Arsenic ii. Sodium iodide (large doses intravenously) iii. Excessive intake of selenium Plants i. Locoweeds ii. Perennial broom weed – Abortions are due to a saponin in the plant iii. Sweet clover hay or silage – Abortions are due to the action of dicoumarol which cause fatal fetal haemorrhage iv. Pine needle – An anti – estrogenic substance may be the toxic agent which cause abortion Ergot poisoning Eating of plants with the growth of fungi claviceps purpurea on plants like rye, wheat, barley and many grasses Toxic principle: Ergonovine – which is one of the alkaloids produced by ergot having oxytocin effect on uterine muscle. Hormonal causes Estrogenic compounds Diethylstilbestrol (Repositol) 100mg upto 4 months of gestation and 25mg or more for each additional months of gestation produced abortion in 3 to 12 days after the injection. Glucocorticoids or hydrocortisone There is a close relationship between the adrenal gland and the maintenance of pregnancy. The adrenal gland can readily convert progesterone and androgens into cortisone and cortisol. Progesterone deficiency 27 Abortions due to progesterone deficiency occurred at 45 to 180 days, more often 83 per cent prior to 100 days of gestation. 500 mgs of Repositol progesterone every 7 to 14 days starting 20 to 30 days before the expected abortion until 200–230 days ofgestation in habitually aborting cows will maintain the pregnancy normally. Pituitrin oxytocin Given during gestation will not cause abortion in animals except horses and primates. Nutritional deficiencies Acute severe starvation may results in abortion in pregnant cattle. Vit A deficiency Usually terminates in abortion in late pregnancy, or in the birth of weak or dead young. Vit a deficiency causes keratinisation of the vaginal epithelium and degeneration of the placenta leading to abortion. Iodine and possible selenium deficiency may cause weak or dead calves at term and abortion in cattle. Physical causes Douching the uterus: Intrauterine insemination or douching from 7 to 60 days of gestation will usually induce abortion in the cow without metritis. If this practice is followed in the third or succeeding months of gestation complications like metritis or fetal maceration may occur. Manual rupture of the amniotic vesicle or rupture of the fetal heart or large vessels by manual pressure in early pregnancy (30 to 60 days of pregnancy) will terminate pregnancy. Removal of corpus luteum: Removal of the corpus luteum of pregnancy in the cow invariably results in abortion. Miscellaneous physical causes i. Sever torsion of the uterus ii. Displacements of the umbilical cord or torsion of the umbilical cord Other causes i. Sever transportation fatigue ii. Severe systemic diseases iii. Major operations In the above conditions excess production of glucocorticoids from the adrenal may be the cause for abortions. Genetic or chromosomal causes i. Inbreeding ii. Trisomy (extra chromosome) iii. Translocation iv. Polyploidy – chromosomal abnormalities 28 Miscellaneous causes i. Twinning in cattle due to the lack of placental area and nutrition for the foetuses. ii. Allergies and anaphylactic reactions. S Clinical Lesions Lab Diagnosis Disease Time No features Placenta Fetus Isolation of agent Serological Blood plate agglutination test Serum 2 nd half of agglutination test gestation Culture of material Vaginal mucus Abortion Brucellosis (7mo) Placentitis, bronchopneu in 10% CO2 agglutination test and 1 Br. enter via necrosis of monia, fetal tension, Semen repeat abortus mucous cotyledons diarrhoea chromogenic agglutination test in breeding membrane potato medium bull s Milk Ring test Whole milk and whey plate agglutination test RB in Mild placentitis with Culture and embryon hemorrhagic examination of Trichomon ic death Early cotyledons, Slightly fetal stomach; 2 iasis Post within 2-4 flocculent exudate macerated Serological test uterine exudates Tr. foetus coital months in fetus and preputial pyometr intercotydedonary washings a areas Cervical mucus RB Culture of material agglutination test PRolong Placentitis, semi Flakes of pus Vbriosis 5-6 in 10% CO2 Mucus to be 3 es and opaque small on visceral V. foetus months tension. Catalase collected after 40 irregular thickenings peritoneum +ve days of suspected estrous service Diffuse placentitis, RB, tan cotyledons and endomet edematous Serum Culturing of fetal Leptospiro ritis, After 6 intercotyledonary Fetal death stomach, placenta agglutination and 4 sis abortion areas microagglutination months common and uterine L. pomona at febrile Phase-contrast lysis test. exudate conditio leptospires and ns fluorescent antibody. Necrotizing Small raised Direct examination Gel diffusion test Mycosis placentitis, thick grey but soft of infected areas using serum for Mucor, leathery lesions or 3-7 for presence of aborted causes 5 aspergillus abortion intercotyledonary diffuse white months hypae and fungal and areas, adventitious areas on skin Culture mycelium as absidia sp placentation. resembling examination antigen Dehydrated fetus worm lesions 29 4. DROPSICAL CONDITIONS OF THE FETAL MEMBRANES AND FETUS Three dropsical conditions of the conceptus may be seen in bovine obstetrics. They are, i. Oedema of the placenta ii. Dropsy of the fetal sacs or membranes iii. Dropsy of the fetus I. Oedema of the placenta or allantois – chorion It is characterized by extensive and severe edema of the fetal membranes. It accompanies a Placentitis Brucella abortus infection causes edema of the allanto – chorion It does not cause dystocia but is frequently associated with abortion II. Dropsy of the fetal membranes It includes hydrallantois and hydramnios. Of all the domestic animals, dropsy of the fetal sacs occurs most frequently in cattle. Overall incidence is 0.3 per cent. Of the two conditions, hydrallantois is encountered most frequently (88%), then hydramnios and both together (5%). In hydramnios and hydrallantois in uniparous animals, the abdomen is usually distended as if twins or triplets are present. Hydramnios It is defined as excess accumulation of amniotic fluid in the amniotic cavity. It is characterized by a gradual enlargement or filling of the filling of the amniot ic cavity that is associated with a genetic or congenitally defective fetus. Species affected Most commonly in cattle; but rarely seen in sheep, pigs and carnivores. It has not been reported in horses. Etiology and pathogenesis At mid-gestation the amniotic fluids is watery and slightly yellow in color. From midgestation onward the amniotic fluid becomes more viscid and glairy because the early watery fluid is swallowed or inhaled into the large bronchi and absorbed and a large volume of Saliva is continually produced. In this way the volume of amniotic fluid remains static after mid gestation. Since this condition is associated with defective fetus, the swallowing is impaired and the amounts or amniotic fluid increases gradually to 20 to 120 litres. Th e normal volume of amniotic fluid is 4 – 8 litres. Genetic or hereditary conditions resulting in defective foetuses often associated with hydramnios are i. Dexter cattle pregnant with “bull dog”calves ii. Angus cattle pregnant with brachygnathic fetus iii. A muscle contracture monster fetus in Red–Danish cattle iv. Pituitary hypoplasia or aplasia in prolonged gestation in Guernsey cattle v. Hydrocephalus fetus in Hereford cattle 30 All the above defects are due to recessive autosomal genes Congenitally defective foetuses such as conjoined twin monsters, Schistosomus reflexus cause hydramnios. Hybrids produced by mating of an American bison bull with a domestic cow resulted in hydrops of amnion. Anencephaly is frequently the cause of hydramnios in humans. Symptoms All cows in which twins are suspected should be examined promptly for dropsical condition. Hydramnios develops slowly over several months during the latter half of gestation. In last month or the last six weeks of pregnancy the conditions causes obvious abdominal enlargement. Often the condition is not recognized until parturition when large quantities of syrupy, viscid, amniotic fluid occasionally containing muconium is released. Abdominal wall is pear – shaped and less tense. In rectal examination uterine horns hard to palpate, not very tense. Placentomes and the fetus may be palpated per rectum. Prognosis The prognosis for the future breeding life of the dam is fair to good but the fetus is defective and dies. Abortions and premature parturitions are frequent in hydramnios Because of the enlarged uterus, uterine inertia and defective fetus dystocia may occur at parturition The genetic implication in salvaging an affected dam should be considered. If the defective fetus and hydramnios is due to recessive character then the dam and sire are carriers. Such animals should be eliminated from the herd and any inbreeding in the herd should be discouraged. Treatment i. At the time of premature parturition or normal parturition with hydramnion, dystocia if any should be corrected and the fetus is relieved. ii. In closed cervix, after confirming the condition, parturition is induced with prostaglandin F 2α or corticosteroids or both. iii. If medical means fail, caesarean section is indicated. iv. Before and after relieving the fetus by vaginal delivery or caesarean section, fluid therapy, antibiotics, antihistaminics and corticosteroids are administered. 31 Hydrallantois It is characterized by sudden and excessive fluid accumulation in the allantoic cavity. This condition is seen sporadically in dairy and beef cattle. Etiology and pathogenesis It is usually associated with a diseased uterus in which most of the caruncles in one horn are not functional and the rest of the placentomes are greatly enlarged and possibly diseased. Adventitious placentae are commonly observed. Commonly seen in cattle carrying twin foetuses. Hydrallantois is caused by structural or functional changes in the allantois–chorion including its blood vessels. It results in transudation and collection of fluid, differing from normal allantoic fluid but resembling plasma. Fetal kidneys seldom play a role in causing this disease. The presence of cystic kidneys, hydronephrosis or dysfunction of the fetal renal tubules resulting in polyuria might be concerned with the pathogenesis of hydrallantois. Vitamin ‘A’ deficiency resulting in a lowered resistance of the endometrium leading to hydrallantois. Hydrallantois usually affects older age cows although it rarely seen in heifers in which congenital lack of caruncles was present. In older cows, this lack of caruncles characteristic of hydrallantois may be due to prior uterine infection or even tuberculous metritis. Clinical signs In mid cases, where the amount of fluid is moderate (40 – 80 litres), the condition may not be diagnosed until parturition. At this time, an excessive amount of clear, watery, amber color fluid with the characteristics of transudate is expelled. The fetal membranes may be tough and rupture with difficulty. The uterus is greatly enlarged and atonic and fetus may exhibit some edema and ascites. Dystocia may occur at the time of abortion / parturition due to inertia. The fetus is usually dead at birth or dies shortly thereafter. In severe cases, symptoms of hydrops of allantois may occur as early as fifth month of pregnancy. Hydrallantois rapidly develops within 5–10 days and is characterized by a distended uterus and enlarged abdomen. In more severe cases, the amount of fluid may reach 80–120 litres, thus, the weights of fluid, membranes and uterus frequently total 350–550 pounds. The excessive volume of fluid distending the abdomen causes the owner to believe that of breeding dates are wrong or else the cow is going to have triplets. Digestive symptoms with anorexia, lack of ruminations and constipation are noted. The cow may drink excessive water. 32 The pulse is elevated to 90 to 140 per minute and is weak and wiry. The cow may exhibit anxiety, restlessness and an expiratory grunt. As the condition progresses, the abdomen becomes more distended. The gait is stiff, slow and cautions. The cow loses body condition and eventually is unable to rise. Dislocation of the hips or backward extension of the rear limbs may occur and the cow lies on her sternum looking like a “bloated bull frog”. Rarely rupture of the prepubic tendon or ventral hernia may occur due to the excessive weight of the uterus. Rectal examination Uterus is distended and tense Placentomes can seldom be felt due to the tense uterine wall but the uterine arteries are whirring indicative of a live fetus. The uterus appears to fill the abdominal cavity. Differential diagnosis (1) Indigestion (2) Bloat (3) Traumatic gastritis (4) Hydramnios Prognosis Prognosis of hydrallantois is poor. In advanced cases in which the cow is unable to rise, the prognosis is often hoepeless. Even if the fetus can be removed the mortality of the cow may occur because the uterus is atonic, the membranes are diseased and shock or severe septic metritis usually follows hydrallantois. Even if the cow survives its reproductive life is questionable. Retained placenta and septic metritis are common sequelae in hydrallantois. Treatment Varies with the duration and severity of the condition. In mild cases: undiagnosed until abortion / premature birth / parturition, excessive volume of fluids are observed accompanied by the presence of a poorly viable or dead fetus. Mutation and forced extraction of these foetuses are usually easily effected. 33 Retained placenta and septic metritis usually follows hydrallantois. Early treatment for these conditions with parentral and local antibiotics and ecbolics such as oxytocin, stilboestrol and ergonovine are indicated. In severe cases with a closed cervix, the prompt termination of the abnormal pregnancy is desired. The parturition is induced with corticosteroids or PGF 2α or both. Assistance and lubrication at the time of delivery is essential. Caesarean section is performed as a last resort. Fluid therapy and proper post– operative care is essential. Following caesarean section, refilling of the uterus also noticed. It requires further drainage. The differences between Hydramnios and hydrallantois Sl. No. Hydramnios Hydrallantois 1 Occurs in 5–10% of the cases of uterine Occurs in 85–90% of cases of uterine dropsy dropsy 2 Abdominal enlargement develops slowly Develops rapidly within 5–20 days over weeks and months 3 Abdominal wall is pear shaped and less Abdominal wall is round distended and tense tense 4 Distended horns of uterus do not fill the Distended horns of uterus easily upper and caudal abdominal cavity palpated per rectum and fill the abdominal cavity 5 Placentomes and the fetus may be Placentomes and fetus are not able to palpated per rectum be palpated per rectum 6 Usually sporadic but in an inbred herd Sporadic in incidence may have number of cases 7 Amniotic fluid is syrupy and viscid and Allantoic fluid is clear. Water and often contains muconium amber colored with a characteristic of transudate 8 Associated with defective, anomalous Foetuses are normal but small twins fetus are occasionally present 9 Placenta and placentomes are normal Placenta especially allantois chorion is diseased and abnormal with a reduced number of greatly hypertrophied placentornes 10 After removing the fluid in caesarean After removing fluid in caesarean section, refilling do not occur in the section, refilling of uterus occur rapidly uterus 11 Retained placenta and metritis rarely Retained placenta and septic metritis follows are the common sequelae 12 Adverse sequelae are rare Uterine rupture, abdominal hernias and dislocation of hips are common 13 Prognosis: fair to good for life and fertility Guarded to poor for life and fertility III. Dropsy of the fetus There are several types of fetal drops and those of obstetrical importance are fetal i. Hydrocephalus ii. Ascites iii. Anasarca 34 Fetal Hydrocephalus Hydrocephalus involves a swelling of the cranium due to an accumulation of fluid which may be in the ventricular system or between the brain and the dura. It affects all species of animals and is seen most commonly in pigs, puppies and calves. In more severe forms of hydrocephalus there is marked thinning of the cranial bones. This facilitates trocarization and compression of the skull so as to allow vaginal delivery. Where this cannot be done, the dome of the cranium may be sawn off with fetotomy wire. Caesarean section is performed in severe cases in cattle when the fetus is presented posteriorly or when the hydrocephalus is accompanied by anykylosis of the limbs. Fetal ascites Dropsy of the peritoneum is a common complication of infectious disease of the fetus and developmental defects like an achondroplasia Aborted foetuses are often dropsical. When the fetus is full term, ascites may cause dystocia. This can be relieved by incising the fetal abdomen withe fetotomy knife. Fetal anasarca It is characterized by great increase in fetal volume caused by excess of fluid in the subcutaneous tissues, particularly of the head and hind limbs. Many of the anasarcous foetuses are presented posteriorly, in which case the enormous swelling of the presenting limbs is very conspicuous. There is frequently an excess of fluid in the peritoneal and pleural cavities with dilatation of the umbilical and inguinal rings as well as hydrocoele. The substance of the fetal membranes is also edematous and occasionally there is a degree of hydrallantois. At the time of delivery multiple incisions are made all over the body of the fetus to reduce the s/c edema and delivery of the fetus. Normal Amount of Normal Amount of Species Species amniotic fluid (in ml) allantoic fluid (in ml) Cow 2000 – 8000 Cow 4000 – 15,000 Mare 3000 – 7000 Mare 8000 –18,000 Goat 400 – 1200 Sheep and goat 500 – 1500 Ewe 350 – 750 Sow 100 – 200 Sow 40 – 200 Dog 10 –50 Dog & Cat 8- 30 Cat 3 – 15 35 5. FETAL MUMMIFICATION Mummification is the death of the fetus at middle of the gestation or at the last third of gestation period which leads to the autolytic changes without putrefaction, abortion of fetal and placental fluids with involution of maternal placenta. Fetal mummification does not occur in the first trimester of gestation because embryonic or fetal death prior to the development of fetal bones follows fetal resorption and absorption of placental tissues. The cause for fetal mummification is difficult to rule out as the time of fetal death is not known and autolysis and mummification of the fetus and fetal membranes makes determination of the causative agent not possible. Susceptible animals: fetal mummification is commonly found in cattle and pigs than sheep, horses, dogs and cats Etiology: Bovines: The general cause for bovine fetal mummification include torsion of the umbilical cord or compression of the umbilical cord passing around the fetal extremity leading to fetal death. Genetic factors involved are due to inherited endocrine defects and autosomal recessive genes (Common in Jersey Breed). There is evidence that fetal mummification may follow infectious causes of fetal death such as campylobacter fetus, moulds, leptospira spp and BVD Swines: Many viruses like Porcine parovirus, porcine enterovirus, Japanese B Encephalitis and SMEDI etc. can cross maternal placenta and kill the conceptus. Dead embryos are usually absorbed without a trace, whereas after 30 days of gestational age when skeletal development begins, will either mummified or aborted Uterine overcrowding and placental insufficiency Ewe: Fetal mummification is generally found with twins or triplets when one of the embryos has died due to infections like epizootic abortion, Listeriosis, Toxoplasmosis and Leptospirosis with prolonged gestation Mare: Mummification is rare and always associated with twins due to lack of placental area. If twinning occurs, one of the foetuses usually develops more slowly than the other. The smaller fetus usually dies. The dead fetus will be mummified and delivered at term along with live foal. Bitch: fetal mummifications is characteristic of canine herpes virus infection and uterine overcrowding Queen: Not uncommon in cats and is due to uterine overcrowding Failure of oestrum. Not suspected until late in gestation when normal development of the fetus, body changes related to parturition and calving fail to occur. Mummy remains in semi-moist state without odour or pus until spontaneous abortion in 1-2 months to 1-2 years, or until diagnosed, treated or corrected or slaughtered. 36 Rectal examination reveals o Persistent corpus luteum (PCL) o Uterine walls contracted and tightly enclose the conceptus o Uterine walls fairly thick o Absence of fetal fluids o Absence of cotyledons, and o Uterine artery small and absence of fremitus. o In early case ▪ Uterus feels doughy due to large, soft blood clot ▪ Difficult to palpate the fetus. o In long standing case ▪ Dry, firm and more leather – like fetus (In cow). Vaginal examination reveals a closed cervix with a mucous seal of pregnancy. Types: There are two types of fetal mummification in domestic animals, they are (i) Hematic type and (ii) Papyraceous type The hematic type is most commonly noticed in cattle in which the maternal placenta or caruncle undergoes involution with a variable amount of hemorrhage occurring between the endometrium and fetal membranes which after the placenta has been absorbed leaves a reddish brown, gummy, tenacious mass of autolyzed red cells, clots and mucus imparting a reddish brown colour to the fetal membranes and fetus. The similarity between the tenacious sticky reddish mucus around the membrane and bovine mummified fetus is striking in this hematic type of mummification. Papyraceous type of mummy occurs in other species and not characterized by placental hemorrhage and hence, the fetus is usually a brownish colour and fetal membranes are not covered with reddish brown tenacious material. Mummification of bovine fetus occurs in cattle at all ages and breeds during the third to eighth month of gestation most commonly in the fourth, fifth and sixth months. If the condition is undiagnosed the mummified fetus will remain in the uterus beyond the normal gestation period. No premonitory signs are observed before the abortion of a mummified fetus and spontaneous abortions are sometimes common. Fetal mummification associated with a persistent corpus luteum is observed mainly in cattle. Torsion of uterus, umbilicus and trauma are considered to be causes for fetal mummification. Wound infection type organisms and Brucella organisms causing fetal death are not followed by fetal mummification. Almost all mummified foetuses and uteri when examined and cultured are sterile and free of organisms and the endometrium gets involved and normal conception occurs in the first or second estrus after explusion of mummified fetus. 37 As the fetus mummifies the uterine walls contract and tightly enclose the conceptus leaving a firmer, dryer leather like tissue with thick uterine wall without cotyledon that can be felt by rectal palpation. Fetal mummification is characterized by failure of estrum with a persistent corpus luteum without any signs of parturition even after the normal length of gestation. The mummified fetus does not give any signal for onset of parturition (normally mature fetus at the end of gestation give signal through hypothalamus-pituitary-adrenal axis for onset of parturition). So corpous luteum remains present and also mummified fetus remains present in the uterus for indefinite time (prolonged gestation). Abnormal cervical seal may be present with the uterus placed in abdomen because of the fetal weight. Haematic mummification Papyraceous mummification only found in cattle Common form Fetal membranes remain surrounded by a Fetal membranes remain contracted, viscous chocolate coloured material wrinkled and dried like parchment Fetal membranes is reddish brown in colour Fetal membrane is brownish in colour due to pigments from RBCs Caruncular haemorrhage occurs No caruncular haemorrhage occurs The bovine fetal mummy remains in the semi moist state without odour or pus until the condition is diagnosed, treated and corrected even upto two years or unless and until examined for prolonged gestation; while in other domestic animals mummified fetus usually remain in uterus only as long as pregnancy is maintained by other viable fetus and expelled with normal fetus at the time of parturition TREATMENT:Any drug which brings about contraction of uterine muscles, relaxation of cervix, involution or regression of corpus luteum and explusion of fetus will be the drugs of choice. Hence induction of abortion by luteolysis using prostaglandins or stimulation of uterus with estrogens can be tried with the fetus getting expelled in 2 –4 days. Administration of corticosteroids and manual stimulation of uterus and dilation of cervix will be no use and not advisable. 1. Prostaglandin injections – Administration of PGF 2α causes regression of CL. After regression of CL, new follicles develop and cow comes to heat, the cervix opens and the mummified fetus comes out of the uterus and usually lodges in vagina (PGF 2α – Lutalyse, Vetmate, Iliren, Dinofertin etc.,) By Intra – muscular route Cattle 25 mg (total dose) Pig 10 mg Sheep & Goat 6 – 8 mg Dog & Cats 0.25 – 0.5 mg/kg s/cly 38 Mare 1.5 – 2.5 mg BID for 2 – 4 days (natural) 250 – 1000 mg i/m (synthetic) 2. Estrogens–(Stilbesterol, Progynon, etc.) Administration of estrogen causes contraction of uterine muscles and relaxation of cervix, regression of CL and expulsion of fetus. Re peated injections at 48 hours may be necessary Total dose – 50 to 80 mg of synthetic estrogens or 5 to 8 mg of estradiol (potent drug) by Intra muscular route. Whether PGF 2α or estrogens are used, expulsion of the mummified fetus may not be complete because of poor dilatation and dryness of the cervix and birth canal. Lubrication of the birth canal and traction are required for the delivery of the mummififed fetus in some cases. Since there is sterile environment of the uterus, there is no need of antibiotic therapy. If manual traction is applied there may be chance of entry of infection, then antibiotic should be recommended After expulsion of mummified fetus, Vitamin A and phosphorous injections should be recommended to restore the uterine epithelial cells for increasing the tone of the uterus 3. When expulsion with the aid of prostaglandin fails the colpotomy approach for removal of a mummy is feasible. It is performed under epidural anesthesia. Exposure varies with the flexibility of the broad ligaments hence is better in older cows. 39 6. FETAL MACERATION Maceration of fetus is the failure of an aborting fetus to be expelled due to uterine inertia in a dilated cervix, when invaded by bacteria causing autolysis of soft tissues and putrefaction leaving the mass of fetal bones within the uterus. Maceration may occur at any stage of gestation in all species but very often in cows. In cows, the fetal maceration which occurs after third month of gestation when fetal bones are fairly well developed and infected through bacterial agents results in death and septic metritis of pregnancy follows, fetal emphysema develops in 24 – 48 hours and in 3 to 4 day maceration begins. If fetal death occurs before ossification of bones, complete microbial digestion of fetus occurs followed by pyometra When death of fetus occur due to bacterial or viral infections, there may or may not be regression of corpus luteum. The parturient phenomenon is initiated but the abortion is incomplete due to incomplete dilatation of the cervix. The fetus undergoes microbial digestion in the fluid of the uterus till the bones remains. The causative organisms are normally those found in the uterus. The micro organisms get a favourable envirointment due to patent cervix and optimum temperature and rapidly multiply. Sometimes the fetal bones penetrate the uterine wall and cause severe damage to the endometrium. The uterine wall will be thick and heavy with a large and hard cervix with fetid discharge from genitalia resulting from severe degenerative and sclerotic changes in the endometrium is observed. In multipara, maceration of early embryos and fetus gets reabsorbed or expelled wit h the placenta and normal co – twin at parturition. Etiological factors causing fetal maceration are 1) Organisms like trochomoniasis and vibriosis present or which invade the genital tract cause infection and pus formation. 2) Uterine interia, improper dilatation of cervix and birth canal that fails to evacuate the fetal content after the occurrence of fetal death. 3) Fetal emphysema and maceration associated with uterine torsion during gestation. Clinical signs: Intermittent straining for several days accompanied by a foul fetid, reddishgrey vulvar discharge Rise in temperature Anorexia Decreased milk yield Occasionally diarrhoea may be present 40 On rectal examination: metallic sound or gritty feeling due
