ENDOMETRITIS

Endometritis is infection of the endometrium.
Endometritis is a common cause of poor fertility in the mare.It occurs following uterine contamination during covering, artificial insemination, reproductive examination, parturition and as a result of poor conformation.

History and signs

• Failure to concieve
• mucopurulent discharge from the vagina
• Early embroynic loss
• Short oestrus cycles

Clinical findings

• Signs of vulval discharge and in some cases failure to concieve.
• Definitive diagnosis is by collection of bacteriological swabs from the cervix or endometrium,which should be under taken under strict aceptic conditions.
• The mere presence of bacteria is not enough to diagnose infections.
• Examination with speculum is an important of the workup and can be performed when the bacteriologic and cytologic swabs are collected

Types

• Venereal Infectious Endometritis
• Non-venereal Infectious Endometritis
• Persistent Post-mating Endometritis
• Chronic Degenerative Endometritis
• Chronic Infectious Endometritis

Venereal Infectious Endometritis

Three major pathogens cause venereal endometritis in the mare:

• Taylorella equigenitalis - causing the notifiable Contagious Equine Metritis (CEM)
• Klebsiella pneumoniae - tests can be performed to identify capsule types 1, 2 and 5 which are sexually transmitted
• Pseudomonas aeruginosa - there is no available test to differentiate strains so all must be treated as pathogenic

The mare may present with vaginal discharge in anacute infection. However she may also present in acarrier state, in which case there may be no outward clinical signs. Stallions are usually sub-clinical carriers of disease. All three bacteria prevent conception.

Equine Viral Arteritis (EAV) and Equine Herpes Virus 3 (EHV-3) are also classified as venereal infections however they do not cause endometritis or prevent conception.

Detailed guidelines on the diagnosis, treatment and prevention of all these infections can be found in the of Practice which are followed by Thoroughbred breeders in the UK.

Non-venereal Infectious Endometritis

This occurs following infection during covering, reproductive examination or foaling. The mare will normally present with a history ofinfertility or early embryonic death and short cycles. There may also be evidence of vaginal discharge. Infection may be caused by:

• Bacterial Infection - Streptococcus zooepidemicus, Escherichia coli or Staphylococcus aureus
• Fungal Infection

Persistent Post-mating Endometritis

This is more common in older and multiparous mares. They present with a history of short cycling and often an vaginal discharge approximately two weeks post-cover.

A transient inflammatory response is normal in the mare post-cover, however a normal immunological response is mounted and the infection cleared before the embryo exits the fallopian tube. In the cases of persistent post-mating endometritis the inflammation persists longer than 72-96 hours so that when the embryo enters the uterus the environment is still unsuitable for embryonic development, resulting in early embryonic death.

Chronic Degenerative Endometritis

Chronic degenerative endometritis aka endometriosis is degenerative change that occurs in older mares or following repeated inflammation of the uterus. If the condition is severe it may result in delayed clearance of the uterus post-cover. Definitive diagnosis can only be achieved by biopsy, which will show degenerative change of the uterus histologically.

Chronic Infectious Endometritis

Normally an underlying conformational condition such as pneumovagina predisposes the mare to chronic infectious endometritis. Definitive diagnosis is again by biopsy which should show infiltration of the endometrium with lymphocytes and plasma cells. Infection may be:

• Bacterial - Streptococcus zooepidemicus, Escherichia coli
• Fungal - more common if there is a history of multiply intra-uterine antibiotic treatments

Prognosis is guarded due to the chronic nature of the infection and the anatomical faults predisposing to infection. Surgical correction of the conformational abnormalities may be attempted using Caslicks procedure.

Diagnosis

• Vaginal examination
• Ultrasound
• Clitoral and endometrial swabs
• Uterine flush
• Endometrial endoscopy
• Uterine biopsy diagnose

Treatment

(1) Uterine lavage with copious amounts of fluid. This is beneficial because it:

removes contaminants such as bacteria and purulent material

stimulates uterine contractions to aid clearance

causes mechanical irritation to the endometrium aiding healthy neutrophil recruitment

2-3 litres of saline or lactated ringers solution should be administered using a uterine flushing catheter and then drained back into the bag and inspected. Dilute Povidone iodine can also be used as a cheap alternative.

(2) Antibiotics (intrauterine or systemic). Antibiotic type should be guided by culture and sensitivity and activity of the drug in the uterus where possible. The length of the treatment should be proportional to the severity of infection.

(3) Administration of ecbolics to stimulate uterine contractility and clearance of infection - oxytocin and prostaglandin analogues

Reference

Manual of Equine Practice by Reuben J.Rose and David R.Hodgson

Pycock, JF (1997) Self-Assessment Colour Review Equine Reproduction and Stud Medicine Manson

Pycock, JF (2004) Pre-breeding checks for mares In Practice 2004 26: 78-85

Ricketts, S (1987) Vaginal discharge in the mare In Practice 1987 9: 117-123

RVC staff (2009) Urogenital system RVC Intergrated BVetMed Course, Royal Veterinary College