Endometritis
Learn what the condition is, how it may be detected early, how it is treated or managed, and which breeds or species are linked to it.
Condition snapshot
A concise guide to the condition’s pattern, detection, management and urgency.
Contagious equine metritis precautions may applyRoutine endometritis is not automatically contagious; follow official breeding controls if Taylorella infection is suspected.
Emergency presentation is possiblePostpartum fever, depression, foul discharge or endotoxaemia requires emergency veterinary treatment.
This snapshot is a general guide, not a diagnosis or treatment plan. New, severe or worsening signs require veterinary assessment.
About the condition
Endometritis is inflammation of the uterine lining and an important cause of reduced fertility in mares. A transient inflammatory response normally clears semen, debris and bacteria after breeding. Susceptible mares fail to clear that material before the embryo enters the uterus, producing persistent breeding-induced endometritis. Infectious endometritis involves bacteria or fungi, while chronic degenerative endometrial change can impair clearance and embryo support without obvious discharge.
Older multiparous mares, mares with poor vulval seal, pneumovagina, a dependent uterus, impaired uterine contractions or cervical damage are at increased risk. Dystocia and retained placenta can produce acute postpartum metritis, a more severe systemic condition that must not be confused with a quiet barren mare. Signs of routine endometritis may be limited to repeated failure to conceive, early embryonic loss, short interoestrous intervals or fluid visible after breeding. Vulval discharge is inconsistent because the cervix may retain material.
Common opportunists include Streptococcus equi subspecies zooepidemicus and Escherichia coli; Pseudomonas, Klebsiella, yeasts and filamentous fungi are less common and often more persistent. Some organisms attach to damaged lining or form protected communities that resist uterine clearance. Taylorella equigenitalis differs because it is transmitted during breeding and creates regulated contagious equine metritis in susceptible populations.
Prognosis depends on uterine anatomy, clearance capacity, the infectious agent and the amount of irreversible endometrial fibrosis. Many susceptible mares can still conceive when inflammation resolves before the embryo enters the uterus. Advanced glandular degeneration, persistent fungal disease or severe conformational failure reduces the chance of carrying a pregnancy even when outward discharge disappears.
The uterus must be clear of damaging inflammation before the early embryo descends from the oviduct. A susceptible mare may ovulate and fertilise normally yet lose the conceptus because fluid, inflammatory cells or fibrosis create an unsuitable environment. Large or numerous endometrial cysts can restrict movement of the early conceptus and reduce the healthy surface available for placental attachment.
Screening & Early Detection
Breeding history is reconstructed, including foaling trauma, barren years, early losses, post-breeding fluid and previous drugs. Examination assesses perineal conformation, vulval seal and discharge, followed by transrectal palpation and ultrasound of uterus, cervix and ovaries. Fluid present in the uterus before breeding or persisting beyond the expected post-breeding interval is significant.
Vaginoscopy and manual examination identify pneumovagina, urine pooling, cervical injury and adhesions. A guarded uterine swab, cytology brush or low-volume lavage is collected aseptically. Culture identifies organisms and susceptibility, while cytology confirms neutrophilic inflammation; interpreting both together reduces false conclusions. Biopsy grades inflammation, fibrosis and glandular change and helps estimate reproductive prognosis in chronic barren mares.
Hysteroscopy or specialist sampling is used for focal lesions and suspected biofilm or fungal disease. Regulated contagious equine metritis testing follows official sampling sites and laboratory rules, including stallion contacts. Postpartum samples are timed with awareness that normal involution causes transient inflammation. Pregnancy is excluded before invasive sampling or treatment.
Samples are labelled with cycle stage, recent breeding and uterine medication because each affects interpretation.
Treatment & Management
Treatment corrects the reason fluid and contaminants remain, not only the culture result. Uterine lavage with sterile isotonic fluid removes inflammatory products, and oxytocin given at an appropriate interval promotes clearance while the cervix is open. Exercise may assist drainage. A Caslick procedure improves a poor vulval seal; cervical tears, urine pooling or other anatomical defects need specialist correction where possible.
Antimicrobials are chosen from culture, cytology and susceptibility and delivered by an effective systemic or intrauterine route for the organism and case. Fungal infection requires prolonged targeted therapy and repeated assessment. Biofilm-disrupting or mucolytic agents may be used in selected refractory cases, but irritating mixtures can damage endometrium. Postpartum metritis with fever or endotoxaemia requires systemic broad-spectrum antibiotics, lavage, fluids, anti-inflammatory therapy and laminitis prevention as an emergency.
Susceptible mares are managed around breeding with minimal contamination, one well-timed insemination, ultrasound for retained fluid and prompt post-breeding lavage and oxytocin when indicated. Treatment response is confirmed by resolution of fluid and, for infection, repeat properly collected cytology and culture after an appropriate interval. Repeated empirical antibiotics without re-evaluation are avoided. Breeding plans account for biopsy prognosis, and embryo transfer may be considered when ovaries are functional but the uterus cannot sustain pregnancy.
Breeds or species affected
Akhal-Teke
Open horse breed description, care requirements and conditions
Anglo-Arabian
Open horse breed description, care requirements and conditions
Arabian
Open horse breed description, care requirements and conditions
Barb
Open horse breed description, care requirements and conditions
Caspian
Open horse breed description, care requirements and conditions
Kathiawari
Open horse breed description, care requirements and conditions
Marwari
Open horse breed description, care requirements and conditions
Shagya Arabian
Open horse breed description, care requirements and conditions
Thoroughbred
Open horse breed description, care requirements and conditions
American Quarter Horse
Open horse breed description, care requirements and conditions
American Paint Horse
Open horse breed description, care requirements and conditions
Appaloosa
Open horse breed description, care requirements and conditions
Australian Stock Horse
Open horse breed description, care requirements and conditions
Brumby
Open horse breed description, care requirements and conditions
Waler
Open horse breed description, care requirements and conditions
Morgan
Open horse breed description, care requirements and conditions
Standardbred
Open horse breed description, care requirements and conditions
American Saddlebred
Open horse breed description, care requirements and conditions
Tennessee Walking Horse
Open horse breed description, care requirements and conditions
Missouri Fox Trotter
Open horse breed description, care requirements and conditions
Rocky Mountain Horse
Open horse breed description, care requirements and conditions
Peruvian Paso
Open horse breed description, care requirements and conditions
Criollo
Open horse breed description, care requirements and conditions
Mustang
Open horse breed description, care requirements and conditions
Canadian Horse
Open horse breed description, care requirements and conditions
Andalusian
Open horse breed description, care requirements and conditions
Lusitano
Open horse breed description, care requirements and conditions
Lipizzaner
Open horse breed description, care requirements and conditions
Friesian
Open horse breed description, care requirements and conditions
Dutch Warmblood
Open horse breed description, care requirements and conditions
Hanoverian
Open horse breed description, care requirements and conditions
Holsteiner
Open horse breed description, care requirements and conditions
Oldenburg
Open horse breed description, care requirements and conditions
Westphalian
Open horse breed description, care requirements and conditions
Trakehner
Open horse breed description, care requirements and conditions
Selle Français
Open horse breed description, care requirements and conditions
Belgian Warmblood
Open horse breed description, care requirements and conditions
Danish Warmblood
Open horse breed description, care requirements and conditions
Swedish Warmblood
Open horse breed description, care requirements and conditions
Swiss Warmblood
Open horse breed description, care requirements and conditions
Australian Warmblood
Open horse breed description, care requirements and conditions
Irish Sport Horse
Open horse breed description, care requirements and conditions
Cleveland Bay
Open horse breed description, care requirements and conditions
Württemberger
Open horse breed description, care requirements and conditions
Zangersheide
Open horse breed description, care requirements and conditions
Knabstrupper
Open horse breed description, care requirements and conditions
Orlov Trotter
Open horse breed description, care requirements and conditions
Camargue
Open horse breed description, care requirements and conditions
Icelandic Horse
Open horse breed description, care requirements and conditions
Pony of the Americas
Open horse breed description, care requirements and conditions
Quarter Pony
Open horse breed description, care requirements and conditions
Miniature Horse
Open horse breed description, care requirements and conditions
Clydesdale
Open horse breed description, care requirements and conditions
Shire
Open horse breed description, care requirements and conditions
Percheron
Open horse breed description, care requirements and conditions
Belgian Draft
Open horse breed description, care requirements and conditions
Suffolk Punch
Open horse breed description, care requirements and conditions
American Cream Draft
Open horse breed description, care requirements and conditions
Ardennes
Open horse breed description, care requirements and conditions
Breton
Open horse breed description, care requirements and conditions
Boulonnais
Open horse breed description, care requirements and conditions
Comtois
Open horse breed description, care requirements and conditions
Dutch Draft
Open horse breed description, care requirements and conditions
North Swedish Horse
Open horse breed description, care requirements and conditions
Norwegian Fjord
Open horse breed description, care requirements and conditions
Haflinger
Open horse breed description, care requirements and conditions
Gypsy Cob
Open horse breed description, care requirements and conditions
Irish Draught
Open horse breed description, care requirements and conditions
Welsh Pony and Cob
Open horse breed description, care requirements and conditions
Connemara Pony
Open horse breed description, care requirements and conditions
New Forest Pony
Open horse breed description, care requirements and conditions
Dartmoor Pony
Open horse breed description, care requirements and conditions
Exmoor Pony
Open horse breed description, care requirements and conditions
Shetland Pony
Open horse breed description, care requirements and conditions
Highland Pony
Open horse breed description, care requirements and conditions
Fell Pony
Open horse breed description, care requirements and conditions
Dales Pony
Open horse breed description, care requirements and conditions
Australian Pony
Open horse breed description, care requirements and conditions
Finnhorse
Open horse breed description, care requirements and conditions
Black Forest Horse
Open horse breed description, care requirements and conditions