Endometritis - Horse

Introduction

Endometritis is the infection of the uterine endometrium

Endometritis,Copyright RVC 2008

Codes of practise******

Equine Endometritis

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

There are several types of endometritis that can occur:

(1) Venereal Infectious Endometritis

(2) Non-venereal Infectious Endometritis

(3) Persistent Post-mating Endometritis

(4) Chronic Degenerative Endometritis

(5) Chronic Infectious Endometritis

Venereal Infectious Endometritis

Three major pathogens cause endometritis in the mare:

• Taylorella equigenitalis - causing the notifiable Contagious Equine Metritis (CEM)
• Klebsiella pneumoniae - tests can be performed to identify 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

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

The mare may present with vaginal discharge (ranging from scant to copious) in an acute infection. However she may also present in a carrier state, in which case there may be no outward clinical signs. Stallions are usually sub-clinical carriers of disease.

Non-venereal Infectious Endometritis

This occurs following infection during covering, reproductive examination or foaling. The mare will normally present with a history of infertility 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. 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 12-24 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 condition such as pneumovagina predisposes the mare to chronic infectious endometritis. Infection 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 treaments

Prognosis is guarded.

Diagnosis

• Clinical examination may reveal vulval discharge or matted tail hairs
• Vaginal examination should identify any discharge and increased vascularity of the tissue. Conformational abnormalities such as pneumovagina and urovagina may be evident.
• Ultrasound examination of the uterus - more than 2 cm of fluid with abnormal character suggests endometritis
• Clitoral and endometrial swabs should be taken for culture and sensitivity. Clitoral swabs should be taken if a chronic venereal infection is suspected. Endometrial swabs should be taken during oestrus to identify and acute venereal infection or identify the causative organism of other endometrial infections
• Uterine flush
• Uterine biopsy

Treatment

• Uterine lavage with copious amounts of saline or lactated ringers solution
• Antibiotics (intrauterine or systemic)
• Administration of ecbolics - oxytocin and prostaglandin analogues
• Antibacterials
• Hormonal therapy - Oestradiol Benzoate and PG

Management of Susceptible Mares

(1) Identify problem mare

(2) Plan a single insemination using a stallion with high fertility rates approximately 1-2 days prior to ovulation. Semen extender may be delivered intra-uterine before cover.

(3) Ultrasound the uterus in the first 12 hours post-cover. The character and volume of fluid present should be assessed.

(4) Remove uterine contaminants via lavage and antibiotic infusion. Administer oxytocin 8 hours after treatment.

(5) Repeat ultrasound examination after 24 hours.

Treatments should not be repeated if possible as this may introduce infection.

Prevention

• Employment of strict hygiene measures during breeding, reproductive examinations and parturition
• Adherence to the Codes of Practise
• Surgical correction of any existing conformational abnormalities

Prognosis

The potential consequences of this condition vary according to the timing and species involved.

The mare will present a considerable problem to: (1) clear the uterine infection;(2) mate again without reinfection or significant fluid accumulation; (3) and because of age-related lowered pregnancy rate and increased pregnancy loss rate, she has a reduced chance of becoming pregnant and carrying a live foal to term. Unless the mare has particular economic or sentimental value, the owner would be well advised to consider whether further attempts to get her in foal are worthwhile.