How to prevent and treat bacterial endometritis in cattle and pigs

Metritis in livestock such as cattle and pigs is mainly inflammation of the endometrium, hence it is called endometritis. Endometritis is usually a mucous or purulent inflammation of the uterine mucosa. Myometritis and perimetritis, however, can occur only in acute postpartum metritis and are also very rare. Endometritis is an extremely common reproductive organ disease in female livestock, and is divided into acute and chronic forms. Acute cases all occur postpartum, secondary to infection by pathogenic bacteria during dystocia, uterine prolapse, or retained placenta; chronic cases mostly develop from acute ones, or result from infection at breeding. When female livestock develop endometritis, they often come into estrus abnormally, or although estrus is normal, they are not easy to conceive, and even if they conceive, they are prone to abortion. For example, among sows that repeatedly fail to conceive, 50% are culled because of this disease. The disease is particularly prominent in purebred sows. Chronic endometritis is one of the important causes of infertility in female livestock such as pigs and cattle.

Causes The main cause of endometritis in female livestock is bacterial infection, mainly caused by common nonspecific bacteria in the natural environment, among which conditional pathogens such as Escherichia coli, Corynebacterium, Streptococcus, Staphylococcus, Pseudomonas aeruginosa, Proteus, and Haemophilus are the most common. In addition, certain specific pathogenic microorganisms such as Mycobacterium tuberculosis, Brucella, Salmonella, Vibrio fetus, bovine rhinotracheitis virus, and bovine diarrhea virus can all cause this disease. Its pathogenesis is most commonly and importantly regarded as occurring through natural infection. The above-mentioned conditional pathogenic bacteria begin to proliferate and cause disease when the body resistance of the female livestock is weakened during parturition, dystocia, and the puerperal period. At parturition, dirty bedding and contaminated pig houses, bacteria invading the injured birth canal, long-term retention of retained placenta, poor disinfection during artificial insemination, retention of lochia during uterine atony, unclean surgery during dystocia, and inflammatory secretions from the reproductive organs or semen of the male animal can all cause endometritis. In addition, abortion, assisted delivery, manual removal of the placenta, and uterine repositioning with poor disinfection or rough handling, insufficient exercise of female livestock, lack of green forage, excessive thinness of sows, and when resistance declines, stress and other adverse factors can also allow conditional pathogenic bacteria in the reproductive tract to cause disease. There is a close relationship between bacterial infection and sex hormones, namely when follicular hormone acts strongly on the endometrium, infection is less likely to occur, whereas when luteal hormone acts on the endometrium, infection is more likely to occur.

Epidemiology Bacterial endometritis occurs sporadically in all herds, and may also become epidemic or endemic. The incidence of endometritis is highest in the postpartum period, when the uterus is most likely to suffer injury and bacterial infection. Uterine involution and repair in female livestock mainly occur in the first week after farrowing, and during lactation other new diseases rarely occur. In pigs, endometritis rarely occurs after weaning, before puberty, and during anestrus. However, young and adult female livestock in the estrous cycle are obviously susceptible, because during estrus the uterus and vulva open, and during the luteal phase the nonspecific resistance mechanisms of the uterus decline.

Clinical symptoms Acute endometritis mostly occurs within a few days after parturition or after abortion, and the effects of postpartum metritis are not limited to reproduction, with obvious systemic symptoms as well. The symptoms in pigs are as follows: sows differ from other livestock. Some sows will show thick, odorless, purulent vaginal discharge during the first 2 days after farrowing, with a volume of about 20 to 50 milliliters; this is a normal phenomenon. Discharge from uterine infection is usually abundant, watery, foul-smelling, and grayish-brown. Infected sows appear ill, such as reduced or absent appetite, failure to lactate, elevated body temperature, dry snout, frequent straining, and red, filthy, foul-smelling secretions flowing from the vagina; if not treated in time, it can develop into septicemia and pyemia or turn into chronic endometritis. When it turns chronic, systemic symptoms are not obvious, and there is crusting or viscous secretion near the base of the tail and vulva, with colors such as pale grayish-white, yellow, and dark gray; when standing, no mucus is seen flowing out, and when lying down, a large amount is discharged. The animal eats but does not gain weight, gradually becomes emaciated, and the sick pig comes into estrus abnormally or with delay, or repeatedly fails to conceive after fertilization, and even if pregnant, embryonic death or abortion occurs not long after. During parturition and postpartum, the uterus of sows is sometimes infected and becomes inflamed.

The symptoms in cattle are as follows: retained placenta is the main cause of postpartum metritis in cattle, mostly occurring from 5 to 8 days after parturition. There are systemic symptoms such as fever (39-41°C), increased pulse and respiration, listlessness, poor appetite, weak rumination, decreased milk secretion, arched back with sunken loin, and straining to urinate. Locally, the main manifestation is a large amount of inflammatory secretion discharged from the vagina, which according to the nature of the inflammation is divided into serous, mucous, purulent, and necrotic. The secretion color may be dirty red, brownish-yellow, etc., foul-smelling, containing floccules or placental fragments, with vaginal congestion, open cervix, and thickened, sunken uterine horns.

Diagnosis Diagnosis by examining vaginal discharge alone is prone to error. For cases of endometritis, it is better to collect secretion from below the base of the tail, or to collect secretion using a vaginal speculum. Comprehensive diagnosis should be made by understanding the systemic symptoms, odor, and the reproductive cycle in which the secretion appears.

Treatment The conventional treatment plan is treatment with antibiotics, and at present florfenicol suspension is mainly used with obvious therapeutic effect. Before use, cut off the seal, and administer directly into the uterine body with an insemination instrument. When treating acute metritis and birth canal infection, inject once every 2-3 days, 1 tube each time; when treating infertility caused by chronic metritis, inject once every 5-6 days, 1 tube each time.

In the acute stage of inflammation, the inflammatory secretion accumulated in the uterus should first be cleared, and 10% physiological saline, 0.02% benzalkonium bromide solution, 0.1% potassium permanganate, 1%-2% sodium bicarbonate, 1% alum, 0.1% rivanol, etc. should be selected for flushing the uterus. After flushing, the residual solution must be expelled. Finally, 200,000-300,000 units of penicillin, 1 g of chlortetracycline, 1 tube of our company's florfenicol suspension, or 1 tube of chlorhexidine acetate suspension can be injected into the uterus; if the sick animal has systemic symptoms, flushing is prohibited.

For chronic endometritis, 200,000-400,000 units of penicillin plus 1,000,000 units of streptomycin can be mixed in 20 ml of autoclaved vegetable oil and injected into the uterus. One tube of our company's florfenicol suspension or 1 tube of chlorhexidine acetate suspension can also be used, which easily maintains therapeutic concentration and can fully give play to the advantages of local medication, such as convenience, safety, and effectiveness, and has been welcomed by a large number of users. In order to strengthen uterine peristalsis and facilitate the discharge of inflammatory secretion from the uterine cavity, uterine contractants (oxytocin injection) may also be used. Administration of drugs into the uterus or flushing drugs should be carried out within several days after parturition or during estrus, because at this time the cervix is open, making administration convenient, whereas administration at other times easily causes uterine damage.

For systemic therapy of endometritis, antibiotics or sulfonamides can be used. Pigs: intramuscular injection of 1,600,000-2,000,000 units of penicillin and 1,000,000 units of streptomycin, twice a day. When using chlortetracycline or oxytetracycline hydrochloride, 40 mg per 1 kg body weight of the sow, twice a day. Sulfadiazine 0.05-0.1 g per 1 kg body weight, twice a day. Satisfactory results can also be obtained by using our company's Rugong'an and Qiang'anlin. For sick pigs with elevated body temperature, intramuscular injection of 10 ml of analgin injection, or 10-20 ml of antipyrine injection.

Prevention Bacterial endometritis occurs as sporadic or epidemic exogenous infection, and is horizontal transmission, also called lateral transmission. This includes direct contact transmission and has long brought relatively large losses to farmers. For dry dairy cows, feeding 3-4 kg of concentrate per day, 15 kg of silage, and free access to green hay is advisable to prevent cows from becoming too fat; inject 20% calcium gluconate and 500 milliliters of 20% glucose solution 2-3 days before parturition and immediately after parturition, once a day. Inject for 2-3 consecutive days, and immediately after parturition inject 100 units of oxytocin intramuscularly to accelerate placental expulsion, which can effectively prevent metritis. Generally, in order to keep infection of the reproductive tract by pathogenic microorganisms and foreign matter to a minimum, when doing sanitation work, attention should be paid to the processes of cleaning, disinfection, and drying, and cleanliness and good drainage should be maintained. Pay attention to ventilation, prevent dampness, avoid reproductive tract injury, and avoid excessively long rest periods and reduction of innate resistance. Ensure the healthy development of animal husbandry and continuously improve the technical level and economic benefits of the breeding industry.