Diagnosis and treatment of bovine endometritis--a review.
Reproductive disorders are the prime reasons for decreased reproductive efficiency in bovines. One of the factors which decrease the reproductive efficiency is endometritis. Endometritis is a common reproductive disorder accounting for about 20% of total reproductive disorders in dairy animals. Abnormal parturition, puerperal complications, inseminations with unsterlized equipments or infected semen leads to uterine infections and finally development of endometritis (Roberts, 1986). Postpartum uterine infection results from uterine contamination with bacteria during parturition (Azawi, 2008).
The bovine uterus is sterile prior to calving. During gestation, the cervix provides a barrier against intrauterine invasion by pathogens for nine months (Dobson et al., 2007). During parturition, the physical barriers of the cervix, vagina and vulva are compromised providing the opportunity for bacteria to ascend into genital tract. Peri-parturient complications like retained placenta, dystocia, twins, dead-fetus, milk fever increase the risk of endometritis because they delay involution and reduce cow's ability to control uterine infections.
Endometritis is defined as inflammation of the glandular layer of uterus and is associated with delayed uterine involution and poor reproductive performance. Endometritis affects the general health of animals and adversely affects their reproductive performance.
Endometritis has either a toxic effect on sperm due to bacterial toxins or varied hydrogen ion concentration in uterus in a manner harmful to the sperm or the fertilized ovum, leading to a large proportion of unsuccessful conceptions. Cows with endometritis are less likely to ovulate because they have slower growth of post-partum dominant follicle in the ovary, lower peripheral plasma estradiol concentrations and perturbation of hypothalamic and pituitary function. The follicular fluid of animals with endometritis contains lippopolysaccharide (LPS), which is detected by the receptor complex on granulosa cells leading to lower aromatase expression and reduced estradiol secretion. If cows with uterine disease ovulate, the peripheral plasma concentrations of progesterone are lower than in normal animals. However, luteal phases are often extended in animals with uterine disease, probably because infection switches the endometrial epithelial secretion of prostaglandins from F to E series; by a phospholipase mediated mechanism, which would disrupt luteolysis. The regulation of endometrial immunity depends on steroid hormones, somatotrophins and local regulatory proteins (Sheldon et al., 2009). The net effect of this disruption of the control centers for reproduction in hypothalamus and pituitary is that there is failure of ovulation, increase cystic ovarian disease and anovulatory anoestrus.
Studies suggest that the annual incidence of uterine infections in post-partum animals range from 10 to 50% of dairy cattle and 20 to 75% of dairy buffaloes (Gilbert et al., 2005). The incidence is also reported to be higher in buffaloes than cows because of the vulvur labia, which is not properly opposed and closed thus greater chances of an ascending infection are reported. With regard to the relationship between calving season and incidence of endometritis, it is evident that calving in autumn was accompanied with a higher incidence of endometritis. In spring and winter, the incidence were similar and lowest for summer season. The higher incidence of endometritis in autumn, spring and winter is also due to unhygienic calving environment during the seasons in which rainfall or moisture may dampen the ground.
The etiology of endometritis is multi-factorial, (bacteria, fungi and viruses) making the disease difficult to diagnose, treat and eradicate. However, majority of endometritis outbreaks in dairy herds are due to bacterial agents (Foldi et al., 2006). The main endometritis causing bacterial pathogens are mixed cultures that include Arcanobacterium, Staphylococcus, Streptococcus, Escherichia, Klebsiella and anaerobic bacteria such as Fusobacterium necrophorum and Bacteroides species.
Types of Endometritis
Endometritis can be distinguished into three types based on the amount of uterine exudates
* Acute endometritis is usually found with a large amount of uterine exudates containing a foul smelling red/brown watery fluid with thin uterine wall. Acute endometritis is usually observed to occur within 21 days post partum with decreased appetite, milk yield, moderate depression and slightly increased rectal temperature.
* Chronic endometritis is observed in animals from 21 days after parturition with abnormal mucopurulent or purulent vaginal discharge clear mucus with flakes of pus, cloudy mucus or mucopurulent with not fully involuted uterus and cervix. The animals may be cyclic or noncyclic.
* Sub-clinical endometritis is an emerging uterine disease and is defined as inflammation of endometrium with significant reduction in reproductive performance in absence of overt clinical signs. Sub-clinical endometritis is the measurement of uterine inflammation using the proportion of neutrophills present in a uterine cytology sample.
Diagnosis of endometritis based on clinical manifestations and rectal examination is not reliable (Roberts, 1986). Although biopsies and culture of uterus have been used as means for diagnosis but these methods are impractical and of limited use in field (Arthur et al., 1989).
Ultrasonography is established in gynecological examination in cattle and is adequate to diagnose endometritis accurately. Further diagnostic methods are cytological, histological and bacteriological examinations (Pleticha and Heuwieser, 2009). Endometritis is a disease that often goes undiagnosed and untreated resulting in reduced conception rates and prolonged inter calving intervals.
Techniques used for diagnosing endometritis
1. Rectal palpation: Clinical findings by rectal palpation of uterus are asymmetrical uterine horns, thickened uterine walls, palpable presence of fluid and cervical diameter of more than 7.5 cm. The normal uterine involution process varies between animals and therefore a good evaluation of the size of the cervix and symmetry of the uterus is difficult and requires repeated examinations.
2. Vaginal examination: Vaginoscopy along with rectal examination has been found to be more accurate method. Cloudy discharge and clear mucus with flakes of pus found on pipette in absence of an enlarged uterus can be regarded as signs for mild endometritis. An enlarged, fluid filled thin wall uterus accompanied with an enlarged cervix and purulent foul smelling discharges indicate severe endometritis.
3. Histopathological examination: Histologically endometritis is characterized by some disruption of surface epithelium, infiltration with inflammatory cells, vascular congestion, stromal edema and varying degree of lymphocyte and plasma cell accumulation in superficial layer.
4. Bacteriological examination: Presence of A. pyogenes and gram-negative anaerobes is demonstrated to be positively related with severity of inflammatory changes in endometrium. The presence of purulent vaginal discharge correlates well with the isolation of A. pyogenes, Bacteroides spp and F. necrophorum where as isolation of E. coli and Streptococci tends to decrease when cervical discharge was more purulent.
5. White Side test: It is an effective tool to diagnose sub-clinical endometritis. The cervical mucus is collected from animals showing signs of repeat breeding in a test tube and equal quantity of NaOH is added and boiled, the change in colour confirms the degree of endometritis.
6. Novel test device Metricheck (a): The current studies compared a novel test device 'Metricheck' that is inserted into the vagina and then examined the relationship between the Metricheck clinical score at 35 days before the start of the breeding. Cows with a history of a peri-partum disease were examined by Metricheck device (Mcdougall et al., 2007).
Endometritis is often self-limiting with recovery occurring after subsequent estrous cycles (Arthur et al., 1989). If Uterine Defense Mechanism (UDM) is impaired or weakened, bacteria may colonize the uterus and lead to development of uterine infection and endometritis. Thus an effective treatment is one which increases uterine defenses and excludes bacterial infections. So, the Ideal therapy for uterine infections, is to eliminate bacteria from uterus but should not inhibit normal UDM and should not cause further adulteration of milk or meat for human consumption.
It has been shown that early treatment of endometritis leads to better conception rates and shorter calving intervals in herds that suffer from the condition. Treatment success rates are higher for mild cases compared to more severe cases and those with a foul-smelling odour (Sheldon et al., 2004).
In general, the current therapies of endometritis can be classified into four types:
a. Use of Prostaglandin [F.sub.2[alpha]] and its analogues
In some cases, prostaglandin ([PGF.sub.2[alpha]]) injections may prove useful. The effectiveness of [PGF.sub.2[alpha]] improves, if corpus luteum is present and although it may help in cases without a CL due to its direct effect on the myometrium, there may be some later impacts on pregnancy rate. The central mechanism of treating with [PGF.sub.2[alpha]] is its luteolytic activity followed by onset of estrus. The myometrium contracts and uterine fluids such as pus can pass through an open cervix (Laven, 2003 and Kasimanickam et al., 2005).
Estrus is associated with spontaneous resolution of disease, whilst uterine immunity is suppressed during the luteal phase. Thus if a corpus luteum is present in an ovary of affected animals, the injection of prostaglandin [F.sub.2[alpha]] or analogues, is a highly effective treatment. It is likely that the reduction in progesterone concentration and the events associated with estrus are as important as the increased estradiol concentrations after luteolysis.
b. Estrogens: It improves the UDM of reproductive tract by increasing the blood circulation, leucocytic infiltration to uterus, uterine contractions, mucus flow and phagocytosis. Small doses (5 or 6 mg) of estradiol benzoate I/M during early post-partum period (after 6 days) are reliable treatment of cows with moderate post partum uterine infections with or with out fetal membranes. However, estrogens and stillbestrol have been associated with more severe infection of oviducts and myometrium development of cystic ovaries and depressed fertility from unknown causes.
2. Intra-Uterine antibacterials
These have been widely used as treatment of uterine infections. Success of these treatments varies from beneficial to no benefit to recommendations against their use. Penicillin may be rendered ineffective due to the presence of bacteria which produce penicillinase (Sheldon et al., 2004). The anaerobic environment of uterus makes aminoglycosides group of antibiotics (Gentamicin, Kanamycin, Streptomycin and Neomycin) ineffective because they require oxygen for their activity. Intrauterine pessaries (either antibiotic or herbal) are the most common treatment for the condition. If intra-uterine antimicrobials are to be used it should be considered at less than 30 days post-partum. Both oxtetracycline and cephalosporins are broad spectrum and effective in the uterine environment and should be considered as the drugs of choice (Sheldon et al., 2004). Use of Cephapirin in cows with endometritis, 3-6 weeks before breeding has been shown to improve fertility (McDougall, 2001).
Intrauterine infusion of Sulfonamides has also been reported (Arthur et al., 1989). Bactericidal activity of Sulfonamides, Amino-glycosides and Nitrofurazone is greatly reduced in an presence of blood, pus, necrotic tissues, products of leukocytes and tissue damage. These antibiotics inhibit phagocytosis. This suppression of leucocytic activity is further increased if bacteria were resistant to applied antibiotic.
Gentle flushing of large quantities (several litres) of warmed saline into the uterus and subsequent siphoning may help to remove some of the uterine content, although this has not been extensively validated (Sheldon et al., 2004).
An antiseptic solution has been reported to be an effective treatment of chronic endometritis (Feldmann et al., 2005). Routinely used antiseptics adversely affect the uterine natural defense mechanisms against infections. In addition, there are chances of ovaro-bursal adhesions, if more doses are given under pressure.
It is obvious from most of the reports that parental and intrauterine treatments with various antibacterial drugs gave inconsistent results. High cost of treatment, compulsory milk disposal, development of resistance to antibiotics, inhibition of uterine defense mechanism (UDM), all led to find an alternative therapy for the treatment of uterine infections. So the people are trying to use substances which cause activation of UDM. These substances when infused into the uterus initiate a local immune system (Dhaliwal et al., 2001). These substances are:
(a) Oyster Glycogen: 1.0 or 10.0% oyster glycogen leads to leukocytosis in uterine lumen by 20-30 folds. Intrauterine infusion of Oyster Glycogen (500mg) led to marked improvement in the non-specific uterine defense and endometrial histopathological picture of cows with acute and chronic endometritis. The live phagocytosing PMNLs in uterine fluid increased within 6hrs, The Bacterial load was almost cleared by 72 hrs of the treatment and conception rate improved tremendously (Subandria et al., 2000).
(b) Serum, Plasma and Hyper Immune Serum: Addition of a small amount of serum to uterine secretions could increase the opsonizing capacity and significantly enhance the phagocytic ability of equine PMN's. This is by the presence of complement, antibodies and opsonins in serum. 50-100 ml of autologus plasma for 3 days can be given by intrauterine route.
(c) Lipopolysaccharide (LPS) of E.coli as Endotoxins: LPS of E. coli infusion to uterus effectively increased the influx of polymorphonuclear leucocytic (PMN) into uterus. By chemotaxis of PMN's to uterine lumen has been reported to play an important role in the pathogenesis and resolution of endometritis. LPS also lead to influx of immunoglobulin helping in phagocygocytosis and killing of bacteria by secretion of cytokines, chemokines and antimicrobial peptides (Sheldon et al., 2009). Studies observed very good results with 100mg of LPS intrauterine when used in cases of endometritis.
(d) PMN extracts and components: The ability of PMN to kill the bacteria is a key component of UDM against microbial infections, The primary and secondary granules (present in neutrophils cytoplasm) enzymes are bactericidal in nature, it has been reported that 100% killing of bacteria from equine uterus by PMN extracts from rabbit origin.
(e) Granulocyte-Macrophage colony stimulating factor (GM-CSF): This is one of those glycoprotein (lymphokines) which helps in differentiation and proliferation of certain Hemopoitic cells and particularly help in formation of mature PMN colonies or macrophages of both. GM-CSF play important roles in body defense against microbial infections as it stimulates neutrophills, increases their phagocytic ability, inhibits their migration and makes them more adherent to the bacteria.
Some disadvantages of intrauterine infusion of immunomodulators are:
a) In severe cases of endometritis and pyometra it is fail to show good response.
b) Loss of one or more than one estrus cycle.
c) Inadvertent administration of infectious organisms in uterus.
d) These agents still need to analyzed for their effective assessment.
Particularly use of carduus compositum has been recommended for the treatment of endometritis (Hemmelchen, 2002).
The factors that have been associated with uterine infection include abortion, dystocia, twins, retained foetal membranes and metabolic disease. On the other hand factors that might have been thought to influence the severity or incidence of endometritis as the hygiene of the farm environment. Thus, paying attention to the hygiene of bovine accommodation and calving facilities will definitely going to reduce the incidences of infection. So cleaner surfaces for animals to lie on, and less contamination of the skin and hair of the animal with bacteria. Perhaps of greater importance is that the liquid faeces, common in dairy herds, likely to contributes bacterial infection of the genital tract as the vulva is oftenly contaminated with dung because of their close apposition with rectum. Thus, there is a greater need for farmers, researchers and dairy veterinarians to adapt new strategies with the aim of reducing the incidences of endometritis contributing to declining fertility in dairy herds. Given that the costs of uterine disease continue to increase, early diagnosis and treatment of endometritis represent a major step towards reversing the declining trend in dairy herd fertility.
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R.G. Agarwal (1), Nitin Kumar Bajaj (2), M.S. Thakur (3), Raman Gupta (4) and Devendra Kumar Gupta (5)
Department of Animal Reproduction, Gynaecology and Obstetrics
College of Veterinary Science and Animal Husbandry
Nanaji Deshmukh Pashu Chikitsa Vigyan Vishwavidyalaya
South Civil Lines
Jabalpur--482001 (Madhya Pradesh)
(1.) Retired Professor and Head
(2.) Assistant Professor
(4.) Post Graduate Scholar
(5.) Assistant Professor (Vety. Medicine) and Corresponding Author
(a) - Product developed by IVRI, Izatnagar
Colour Degree of Endometritis Turbid or No Normal Light Yellow Mild Endometritis Yellow Moderate Endometritis Dark Yellow Severe Endometritis
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|Author:||Agarwal, R.G.; Bajaj, Nitin Kumar; Thakur, M.S.; Gupta, Raman; Gupta, Devendra Kumar|
|Date:||Jan 1, 2013|
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