Introduction
Parturition is the natural biological process of delivering a fully developed fetus at the end of the gestation period. It is primarily triggered by the secretion of fetal cortisol, which acts on the placental trophoblast to increase the activity of COX-2 (Cyclooxygenase-2), resulting in the pjordan proto max 720 custom youth hockey jerseys fsu football jersey durex intense vibrations ring oregon football jerseys uberlube luxury lubricant deuce vaughn jersey uberlube luxury lubricant air jordan 1 element air max 270 women nike air max 90 futura blundstone uomo custom sublimated hockey jerseys uberlube luxury lubricant custom stitched nfl jerseyroduction of PGE2 (Prostaglandin E2). This, in turn, leads to the conversion of progesterone to estrogen by enhancing the activity of 17α-hydroxylase. The increased levels of estrogen further stimulate the activity of endometrial COX-2, which causes the release of PGF2α (Prostaglandin F2α). PGF2α plays a pivotal role in inducing endometrial contractions by synthesizing contraction-associated proteins (CAPs), such as connexins. These contractions are essential for the initiation of parturition. The prostaglandins also play a crucial role in luteolysis, causing the regression of the corpus luteum. Additionally, they induce uterine contractions, which progressively increase in both frequency and amplitude, ultimately leading to the expulsion of the fetus from the uterus. During parturition, abdominal contractions triggered by a pelvic reflex also contribute to the expulsion of the fetus. This entire biological process of parturition can be divided into three stages:
1. The first stage is characterized by active contractions of the uterine wall muscles and the dilation of the cervix.
2. The second stage involves the entry of the fetus into the dilated birth canal, the rupture of the first amniotic sac, the occurrence of abdominal contractions, the appearance of the amniotic sac, and finally, the expulsion of the fetus.
3. The third stage is the period during which the fetal membranes are expelled.
These stages collectively ensure the successful delivery of the fetus and are regulated by complex hormonal and physiological mechanisms to prepare the mother and fetus for the birthing process.
In bovines, the normal expulsion of placental membranes typically occurs within a timeframe of two to eight hours after the birth of the calf. When the fetal membranes are not expelled within this 24-hour period, they are considered as retained. Retained fetal membranes can be a concern in cattle and may require veterinary attention and intervention to ensure the health and well-being of the cow.
Incidence
The incidence of retention of placenta in cattle is influenced by several factors, and it tends to vary based on specific conditions and characteristics. Here are some key points regarding the incidence of retained placenta in cattle:
- Parity: The incidence of retained placenta tends to increase with parity, which refers to the number of times a cow has calved. Cows with higher parity are more likely to experience retained placenta compared to first-calf heifers.
- Twin Births: Cattle that give birth to twins are at a higher risk of retained placenta. The presence of multiple fetuses can complicate the birthing process and increase the likelihood of placental retention.
- Late Abortions: Late abortions can also increase the risk of retained placenta. These are pregnancies that terminate closer to full term.
- High-Yielding Dairy Animals: High-yielding dairy cows, which produce large quantities of milk, are more prone to retained placenta. The increased metabolic demands of high milk production can affect the cow’s ability to expel the placenta after calving.
- Nutritive Plane: Cattle kept at high nutritive planes, meaning they receive ample nutrition, are more susceptible to retained placenta. This may be due to the impact of diet and nutritional factors on the birthing process.
- Incidence Rates: The incidence rate of retained fetal membranes can vary by region and management practices. As mentioned, it is approximately 20-25% in buffaloes and 18-20% in dairy cows, although these rates may fluctuate based on specific conditions and herd management.
Managing the risk factors associated with retained placenta, such as proper nutrition, monitoring twin pregnancies, and providing appropriate care during late abortions, is important for reducing the incidence and ensuring the health of the cow and calf. Additionally, timely veterinary intervention may be necessary in cases of retained placenta to prevent complications and infections.
Normal physiology of separation and expulsion of placenta
Three major events are responsible for normal expulsion of fetal membranes. Foremost important is maturation of placenta and this has to be accompanied by second major event i.e. exsanguination of fetal side of placenta due to rupture of umbilicus. This causes collapse and shrinkage of the trophoectodermal villi and their separation from maternal crypts. Various hormonal changes taking place during parturition are responsible for maturation and detachment of fetal and maternal part of placenta. The increased activity of collagenase enzyme is mainly responsible for breakdown of fetal cotyledon and maternal caruncle interface. The third major event is myometrial contractions which aid in exsanguinations of fetal side of placenta and cause unbuttoning of the cotyledon from the caruncle and finally its expulsion.
Causes of retention of placenta
The causes of RFM are multiple like selenium or vitamin A deficiency, heat stress, pre-mature calving, uterine atony, stillbirths, abortions, dystocia and excessive weight gain which influence the degree of hyper-trophication and interdigitation of the microvilli of cotyledons with the crypts of caruncles due to changes in energy balance.
On the basis of process of separation and expulsion of fetal membranes it is divides into two major classes of causes; Group 1 includes the causes that interfere with normal loosening process between the fetal and maternal part of placenta i.e. immature placentomes, prolonged gestation, necrosis, inflammation and edema of chorionic villi and hyperaemia of placentomes. Group 2 includes the causes that mainly interfere with expulsion of fetal membranes i.e. uterine distension, secondary uterine inertia and metabolic disorders like postpartum hypocalcemia. So, in nutshell any of the above causes may result in retention of the fetal membranes and may pose a threat to uterine health and this rational treatment has to be done in time to avoid the production of adhesions and septicemia.
Treatment
Manual removal:
An ideal practice would be to carry out careful aseptic exploration of the uterus of the affected cow within 1 day of parturition & to remove the membranes if the fetal cotyledons can be completely detached without injury to maternal caruncles. If it is found impractical to remove then on first examination, the examination may be repeated at daily intervals until the membranes could be removed. However, it is frequently found that attempts at removal during the first 48 hours are unsuccessful for the placenta is than too firmly attached & vigorous manipulation to free the afterbirth is likely to cause hemorrhage& even detachment of maternal caruncles. Moreover, the apical part of the gravid horn is at this time usually beyond the reach of obstetrician hand. For these reasons it has become a common practice to delay interference until day 3 or 4.
Therapeutic treatment without manual removal:
Oxytocin: Can be used within 24 hours of the birth of the calf & is may be beneficial in some cases of retention which are due to primary inertia. It is given 100 I.U. after parturition. Estrogenic substances increase the sensitivity of the myometrium to oxytocin & enhance the natural uterine defence mechanism. For this reason the synthetic estrogenic stilbestroldi propionate, oestradiol mono benzoate are widely used as parenteral injections or uterine infusions & pessary & their use has sometimes been followed by injections of oxytocin. As retention of placenta is also due to uterine inertia & which is sometimes due to hypocalcaemia. So calcium thereby is beneficial either by I/V or oral route. In cases where systemic illness appears parenteral antibiotics are used. A great variety of antiseptics & antimicrobials agents have in the past been introduced into uterus in retention cases to check bacterial multiplications. Oxytetra cyclines administered at therapeutic dose rates are frequently used. They may exert a beneficial effect on the associated metritis & reduce putrefaction & by retarding lysis may prolong retention. It is also noted that I/U use of the oxytetra cycline leads to worse conception rates. Neomycin & Metronidazole (in vitro) is more effective than oxytetra cycline. Supplementation with liver toxins because if at all there are any toxic substance, the first organ effected is liver & to treat the anorexia in animals. Some workers prefer the use of PGF2 alpha immediately after parturition or few days later @ 25 mg I/M because it also leads to uterine contractions. Treatment of retained placenta with umbilical cord injection of collagenase in cow: Injection of 200,000 I.U. of bacterial collagenase in 1000 ml of physiological saline solution via umbilical arteries (1 or 2) between 24 to 72 hours of retention causes release of retained fetal membranes within 36 hours after injection. Also the use of collagenase via a jugular vein in 1000 ml of physiologic saline solution, administered over a 30 minutes period, cause release of retained fetal membranes within 36 hours. Umbilical injection of bacterial collagenase is highly effective in treatment of retained placenta in cows. Procedure is simple, safe, and affordable & can be completed in 25 minutes.
Traditional treatment under field condition:
•Wait for expulsion of placenta for 12 hours.
•Milking of animal as early as possible because it will produce the endogenous production of oxytocin which helps in placental expulsion by inducing contractions.
•Administer oxytocin parenterally 50 -100 I.U at 2-3 hours interval. But single shot is enough.
•When case is presented as a delayed case then: Traditionally placenta was tied with some object like shoe & other objects, but it should not be done.
•Ergot preparation can be given immediately after parturition. It is a supportive treatment. It acts as ecbolic & digestive tonic.
Immunosuppression and retained placenta
The transition from pregnancy to lactation is also characterized by a sharp but transient depression in the immune system, which may play a role in the occurrence of retained placentas & susceptibility to other disease. Indeed, Plasma Vitamin E (alpha- tocopherol) levels have been shown to lower as much as 47% at calving. Feeding high levels of Vitamin E (1000 IU / hd/ d) reduce the incidence of retained placenta when fed for 21 days immediately prior to calving. Vitamin E seem to enhance the immune system’s response to the placenta after circulating levels of progesterone & glucocorticoids have dropped following calving.
Prevention
Prevention of retained placenta of course is the key. It may be rather difficult to pinpoint the exact cause with so many direct or indirect factors than can be incriminated. The optimum is to maintain a healthy, contended & active cow prior to, during & after parturition. A balanced, limited ration during the 6-8 weeks dry period; sufficient daily exercise, sufficient large, clean & comfortable calving area & proper sanitary procedures during the calving period minimize the chances of retention & infection of reproductive tract.
There are several specific preventive measures to follow:
•In selenium deficient or borderline areas, the administration of dietary level of selenium (0.1 ppm) tended to minimize the incidence of retained placentas.
•Vitamin A & D deficient cows have high retention rates. I/ M injection of vitamin A & D may be given 4-8 weeks prior to calving if deficiency is suspected.
•The calcium: phosphorus ratio for the dry cow is extremely important in the prevention of milk fever & in turn, retained placenta. Maintenance of Ca: P ratio of 1.5: 1.0 & 2.5: 1.0 is absolutely necessary. Above 2.5: 1.0 the incidence of milk fever & retained placenta increases. Supplementary Phosphorus may have to be fed to dry cows to maintain the proper ratio as recommended by veterinarian.
Conclusion
Retention of fetal membranes (RFM) is a common abnormality found in 5-10% of normal calvings and its prevention includes a stress-free environment for animal and careful and mutritional management during pregnancy and around parturition. Lack of exercise, low vitamin-A in feed may contribute to higher incidence. Use of appropriate antibiotics and ecbolic agents along with supplementation of vitamin- E and selenium may be an effective measure to treat this condition.
Retention of Fetal Membranes in Bovine-a Major Impediment After Parturition
Popandeer Kour (Ph.D. Scholar, Department of Veterinary Gynaecology and Obstetrics) and Dr. Bilawal Singh (Assistant Professor, Department of Veterinary Gynaecology and Obstetrics)
Guru Angad Dev Veterinary and Animal Sciences University, Ludhiana, Punjab, India
