Endometritis is one of the main causes of infertility in mares due to reduced pregnancy rates. It consists of a inflammation of the uterus due to an infection caused by various agents that reach the uterus, mainly due to inadequate hygiene in the examination of mares, contamination in the coverage, a deficient uterine defense mechanism or defects in anatomical conformation. Uterine lavage, together with drugs that increase the contractility of the uterus, is the most used therapy and with the best results for equine endometritis, but without forgetting the specific therapy for the causal agent.
In this article on our site, we will discuss Equine endometritis, as well as its causes, diagnosis, symptoms and treatment.
What is equine endometritis?
Equine endometritis is an infectious disease consisting of inflammation of the uterusand the uterine mucosa of mares. The main consequence of this disease is the decrease in pregnancy rates due to not getting pregnant, presenting early embryonic death, abortions mid-gestation or placentitis.
All mares after mating develop a endometritis to some degree, because the deposition of semen in mares is intrauterine, so both seminal components and bacteria will enter, causing inflammation. However, they normally clear it effectively within 48 hours by their uterine defense mechanism (recruitment of defense cells from your body, production of antibodies, and uterine contractions), while if they are susceptible, this process is prolonged and complicated.
Risk factors in equine endometritis
Mares are more predisposed to prolonged post-mating endometritis:
- With anatomical defects that cause poor fluid drainage.
- Those with poor perineum conformation.
- Those with urovagina (urine in the vagina) or pneumovagina (air in the vagina) due to previous birth trauma.
- Older women who have given birth and the uterine muscles have descended a lot at the abdominal level, limiting the exit of the exudate to the outside.
- Those with uterine contractility dysfunctions, alterations in the inclination of the vaginal canal or pendulous uterus.
For more information, you can read this other article on How do horses reproduce?
Symptoms of endometritis in mares
The clinical signs shown by mares with endometritis will depend mainly on the severityof the infection and of the time you have been with it. In mild or subclinical cases, the mare will only show signs of subfertility, such as heat repetitions and short heat cycles. In symptomatic cases we can see the following alterations in the mare:
- Serous, mucous or purulent discharge from the vulva.
- Agglutination of tail hairs by secretions.
- Wet flanks.
- Congestive and edematous uterus with exudate.
- Increase in the size of the uterus.
- Vaginitis.
- Increased color of the vagina and vulva, with discharge coming out of the cervix.
Causes of endometritis in mares
Endometritis in mares is mostly caused by bacteria, followed by fungi:
- Bacteria: the most commonly implicated bacteria are Streptococcus equi sub esp. Zooepidemicus, Escherichia coli and Staphylococcus spp. There are other bacteria found on the genitalia of male horses that, during mounting or veterinary handling, invade the mare's genitalia and uterus. These bacteria are Klebsiella pneumoniae, Pseudomonas aeruginosa, and Taylorella equigenitalis. The latter is the causal agent of a highly contagious venereal disease known as contagious equine metritis, which is transmitted by the stallion during copulation and causes mucopurulent discharge, vaginitis, endometritis and cervicitis, which generates temporary infertility, abortions and can give rise to fetuses. carriers if the mother becomes infected at term of pregnancy. These microorganisms are generally contracted after mating, by retained placenta and exudates after childbirth, after dirty artificial insemination, by genital examinations with contaminated instruments, as well as when they present anatomical defects.
- Fungi: endometritis caused by fungi is usually due to the frequent and indiscriminate use of antibiotics that destroy the bacterial flora, so the fungi do not find competition, which together with changes in the mare's uterine pH is what allows their multiplication, highlighting the yeast Candida albicans and the fungus Aspergillus fumigatus.
How is equine endometritis diagnosed?
To diagnose endometritis in mares, it is necessary to base it on the symptoms they present, their physical examination, a transrectal ultrasound, a vaginal and cervical examination, as well as a culture, uterine cytology and endometrial biopsy.
Clinical, vaginal and transrectal diagnosis
In the mare we will see the aforementioned clinical signs, also if a vaginoscope is used, it will reflect an increase in coloration (hyperemia) from the vagina, with the presence of exudate from the uterus exiting through the cervix or cervix, which will be congested and edematous. If you observe urine or air in the vagina it is indicative of urovagina or pneumovagina, respectively, which, as we have mentioned, predisposes to suffering from endometritis, as well as vaginitis and cervicitis (inflammation of the vagina and cervix).
During the rectal examination, the uterus will appear enlarged and softer in consistency due to edema caused by inflammation.
Cytology and culture
Samples are taken from inside the uterus. It is important to wash the mare's genitalia to avoid taking a contaminated sample. Samples may also be taken from the clitoris and vaginal vestibule if a venereal disease is suspected.
Once the sample is taken, it is stained and viewed under a microscope. If more than two neutrophils (the first defense cells to arrive against a foreign microorganism) are observed in five fields at 400 magnification, it is indicative of inflammation, and will allow to see bacteria, yeast or fungal hyphaeThe result is also positive if a pathogenic microorganism grows in the culture. For this, the medium Blood Agar at 37 ºC is usually used. After a few days, the colonies that have grown, their morphology, color and the bacteria involved will be determined. Cytology is more effective, as sometimes the culture is negative and the cytology positive.
Biopsy
It is very useful for to assess the state of the uterus, its cells (which indicate at what stage of the cycle the mare is), the state of the inflammation and if it is cultured from it, the diagnostic result is much higher. Depending on the cells that the biopsy shows, it can be known if the bacterial endometritis is acute (neutrophils will be seen), chronic (lymphocytes and plasma cells) or if it is fungal (eosinophilic infiltrate). The only drawback is that it is an invasive technique and can alter the mare's reproductive cycle.
Studies confirm that uterine endometrial biopsy is the most reliable diagnostic method for equine endometritis.
Ultrasound
By performing this imaging technique using a rectal probe, it is possible to determine the presence of fluid in the uterus, its volume and its characteristics (if it looks like pus or is serous), indicating the severity of the disease.
Treatment of endometritis in mares
Treatment of equine endometritis will depend on several factors, including age, parity, and results of cytology, culture, or biopsy.
For proper treatment of endometritis in mares, medical treatments must be instituted such as specific drugs for the causal agent, uterine lavage and anti-inflammatory and antiseptic therapy.
Uterine lavage
It is very useful to reduce inflammation by eliminating microorganisms and exudate. It stimulates uterine contractions that help expel fluids, causes some irritation in the endometrium, which causes the arrival of new defense cells to combat infectious agents and ends up increasing the pregnancy rate. Use between one and two liters of an isotonic saline solution or Ringer's Lactate at 40 or 50 ºC temperature
The use of drugs such as oxytocin or prostaglandins is also recommended, which increase uterine contractions and improve drainage of exudates through washing.
Antibiotics
The selection of the antibiotic in each case must be the one that has resulted in the culture antibiogram. In this way we will apply the really effective treatment and avoid the appearance of resistance.
They should be applied locally in the uterus and not applied systemically, as they have more effect. They are usually given every day for 3, 5 or 7 days, depending on the severity of the endometritis. Antibiotics from the beta-lactam group (penicillin, ampicillin…), aminoglycosides (gentamicin, kanamycin, amikacin) or the cephalosporin group are usually used.
Antifungals
When fungi are responsible, antifungals such as amphotericin B, clotrimazole, econazole or ketoconazole are used.
Anti-inflammatories
From the group of glucocorticoids such as dexamethasone, they lead to a reduction in edema and exudates from the uterus. Nonsteroidal anti-inflammatory drugs (NSAIDs) such as vedaprofen or flunixin meglumine can also be used to avoid the side effects of corticosteroids.
Antiseptics
The use of antiseptics such as hydrogen peroxide, chlorhexidine, povidone-iodine or diluted acetic acid, m is usually done when there is presence of fungi, it is not known what type of infection the mare has because it has not been tested or sensitive antibiotics are ineffective or inapplicable.
These antiseptics cause a decrease in the size of the uterus, an increase in its blood supply and a decrease in the viscosity of the fluid, helping its expulsion. But keep in mind that are irritating, they can destroy defensive cells (neutrophils) and cause uterine adhesions.
How to prevent endometritis in mares?
As we have been seeing, this disease is closely linked to contamination during copulation, insemination or handling, so the following measures must be taken:
- Proper hygiene during artificial insemination or mating.
- Limit the number of matings by selecting the right time in our mare's cycle.
- Cleaning of the external genitalia.
- Extensive instrument disinfection.
- Application of mannose sugar before mating or artificial insemination, as it generates a protective layer that limits the binding sites of bacteria to the endometrium.
- If the mare has a urovagina or pneumovagina, vulvoplasty is indicated to correct the problems.
- If there is a retained placenta or delayed involution of the uterus after delivery, they should be treated as soon as possible to avoid uterine contamination.
Equine endometritis usually has good prognosis, but in mares with chronic or recurrent endometritis that do not respond to antibiotic therapy, this inflammatory process usually severely affects your fertility. Therefore, in the event of infertility or clinical signs such as discharge from the vulva, call the equine veterinarian to diagnose the process and be able to act as soon as possible against this disease that affects our equine females.
For more information, you can consult this other article on How to know if a mare is pregnant?
