Septic Metritis in Animals

Septic metritis is an acute inflammation of the uterus that occurs within 1–10 days after parturition (giving birth), characterized by the presence of systemic infection signs such as septicaemia (bacteria in the blood), toxaemia (toxins in the blood), and pyaemia (pus-forming bacteria in the blood).

Usually it followed by prolonged dystocia, fetotomy operation, fetal emphysema, severe torsion of uterus with presence of dead fetus, dropsy of fetal membranes, fetal anasarca, fetal gigantism, twinning and peritonitis due to traumatic gastritis, prolapsed uterus and improper handling of RFM. Occasionally from necrotic vaginitis.

Clinical Signs

• Anorexia, dullness, rapid pulse, elevated body temperature
• Animal may shiver and extremities are cold
• Rapid and shallow respirations
• Sunken eyes
• Rough hair coat
• Atony of digestive tract
• Drop in milk production
• Fetid red watery uterine fluid that is very toxic and depressing to the animal.
• Uterus is atonic and thin
• Cow may exhibit characteristic grunt due to peritonitis

Treatment

Before prescribing an antibiotic the following points must be taken into consideration for septic metritis cases:

• Isolation and invitro sensitivity to antimicrobial agents: In general, disc test give valuable results, however, there is marked discrepancy between the results of the test and the clinical response of the patients. A few possible explanations for such discrepancies are listed below.
• Failure to drain the pus or remove a foreign body. Antimicrobial drugs almost never eradicate microorganisms within an abscess or in the presence of pus.
• Because of pharmacological properties, drug may not reach the site of active infection.
• In occasional cases 2 or more microorganisms participate in an infectious process but only one of them may have isolated from specimen.
• The drug being used may be one that is effective only against the less pathologic organisms.
• Massage and douching of uterus, attempts to remove retained fetal membranes should seldom advised or it would adverse the condition.

This table shows the list of antibiotics preferred for various causative organisms responsible for infections of reproductive tract.

Selection of antibiotics in the treatment of reproductive tract infection, based on their in vitro sensitivity against some important organisms.

The other factors which determine the selection of antibiotics are:

• Dosage and route of administration
• Induction of resistance
• Age, sex, species and body defence mechanism
• Indications of combination is seldom localized to only superficial layer

Antimicrobial preferred for treatment of uterine infection:

• Ampicillin
• Oxytetracycline
• Gentamicin
• Streptomycin and Penicillin G
• Neomycin
• 2^nd and 3^rd generation Cephalosporins
• Fluoroquinolones

Route of administration preferred for treatment of uterine infection for clinical purposes antibiotic therapy has been used by two routes.

• Intra uterine
• Parenteral (I/V or I/M)

Penicillin

After I/V or I/M administration, the concentration in uterus is sufficient and several fold higher than Minimum Effective Concentration (MEC). The MEC is maintained for 8 hours. The endometrial concentration achieved after I/V route was although considerably less than those achieved following intra uterine infusion.

Ampicillin

The MEC of ampicillin (0.1ug.ml-1) after I/M or I/V route remain maintained for 4-6 hours in uterus and 6-8 hours in plasma. The peak concentration of ampicillin in plasma and uterus is 17.8 and 1.1ug ml-1, respectively.

Sulphonamides

When sulphonamides is administered by parenteral route, the uterine tissue concentration is several fold higher than the corresponding plasma consideration.

Aminoglycosides

Single I/M injection of Streptomycin (10mg/kg) attains peak concentration of drug (5.1±0.5g/ml) in uterine fluid at 1 hour. Gentamicin also penetrates well in endometrium. If gentamicin is administered for 7 consecutive days the mean endometrial concentration on day 4, 5, 7 and 13 are 5.0±3.3, 12.8±1.6, 18.6±1.2 and 22.5±1.6/ml, respectively.

Chlorampenicol

When Chlorampenical is given by continuous intravenous infusion, the concentration in caruncles, endometrium and uterine wall is approximately 3 fold higher than in plasma.

Tetracyclines

Similar to chlorampenicol, oxytetracycline also achieves more concentration in uterus as compared to plasma. The mean tissue / plasma. The mean tissue / plasma ratio of oxytetracycline after its i/v administration ranges between 1-2 for various parts of uterus.

New Concepts in Antimicrobial Therapy of Uterine Infections

It has been established that parenteral injection of antibiotic achieves the MEC of drug in uterus and it remain maintained for longer time. Hence parenteral administration of antibiotics may be preferred over intrauterine administration in uterine infections.

Intrauterine administration of drug is not contraindicated but should be avoided because the pathological barrier viz. Pus, exudates, blood and inflammatory barrier may affect the therapeutic efficacy.

It is not confirmed that, after intrauterine route, drug directly diffuses into uterine cell or first absorbed into blood vessels, goes into systemic circulation and then gets distributed into uterine tissues. Clinicians may introduce infections and stress to the uterine tissue which is already under stress and infection.

Recommendations

• Treat the uterine infection by parentral injection.
• If essential, give first does by intrauterine route and then the MEC by subsequent parentral injection.

Placental Transfer of Antibiotics

The administration of antibiotics to pregnant must be based on the physiological changes and the resultant alterations in pharmacokinetics that occur during pregnancy. In addition physician must always be alert to the possible deleterious effects of drugs or fetus.

Infectious that require antimicrobial across the placenta due consideration should be given to following points before the administration of any of these drugs.

• No therapeutic agent of any structure and description should be considered completely safe for developing fetus.
• Rapid equilibration occurs between the fetal and maternal circulation and fetal exposure to pharmacologically active compounds is far more extensive than is generally accepted.
• The potential benefits must overweigh the possible hazards of the drug to both mother and fetus.
• The effect of the therapeutic agent on the fetus may not necessarily be the same as the expected pharmacologic effect on the mother.
• Drug metabolism in pregnancy is much slower than in the nongravid state. Due consideration should, therefore, be given to the dosage and route of administration.
• Certain drug effects last much longer in the fetus than the mother.

Hormonal Therapy

Oestrogen has been administered to initiate or strengthen myometrial contractions, but its use is controversial.

Contraindications induced by estrogen have been blamed for forcing the septic contents of the uterus not only through the cervix but also onto the uterine tubes resulting in severe bilateral salpingitis.

Oxytocin causes contraction of myometrium if the organ is dominated by estrogen Thus oxytocin is expected to be effective in aiding uterine evacuation if administred within 48-72 hours after calving. Doses of 20-40 IU repeated every 3-6 hours are commonly used Cows treated with PGF2α in early postpartum followed by second dose of PGF2α 14 days later resulted in higher conception rate than untreated cows.

Prognosis

Recovery from postpartum infections varies with severity of the condition. Most cows with uncomplicated endometritis can expected to recover metritis complicated by septicaemia may result in permanent impairment of fertility, decreae milk yield, laminitis.