SAEVA Proceedings 2016 | Page 13

  some cases, the manipulation involved in recovering a swab or inseminating the mare can reactivate such a ‘latent’ infection, and this is essentially the rationale underlying the use of Tris-EDTA (to disrupt biofilms), N-acetyl cysteine (to remove excess endometrial surface mucus) or Bactivate® (to activate ‘dormant’ streptococci) to uncover a latent infection. How often such treatments are really helpful is, at present, unclear although they are only likely to be of any relevance to the 10-15% of mares that fall into the category ‘susceptible’ to persistent mating-induced endometritis (PMIE). Therapy In terms of the therapeutic approach, endometritis can usefully be divided into two major categories, pre-existing microbial endometritis, and inflammation triggered by the introduction of semen into the uterus. Until relatively recently, the focus was on the diagnosis and treatment of existing (i.e. prior to a proposed breeding) uterine infections with bacteria or, occasionally, fungi or yeasts. When an active endometritis is detected, treatment consists of uterine lavage to debulk bacteria and inflammatory fluid, combined with uterotonics to assist uterine evacuation and (intrauterine) administration of a course (usually 3- 5 days) of appropriate antimicrobials, preferably during oestrus when uterine resistance to infection is maximal. In the case of the venereally transmitted bacteria (Taylorella equigenitalis, Pseudomonas aeroginosa and Klebsiella pneumoniae capsule types I, II and V), contemporaneous antimicrobial treatment of the vagina and clitoris is recommended to ensure removal of potential reservoirs for re-infection. Fungal endometritis is an uncommon condition in mares, accounting for less than 5% of diagnosed endometritides. It is generally accepted that fungal infection is opportunistic and will only establish in a chronically disturbed uterine or vaginal environment; pneumovagina, persistent endometritis and repeated intrauterine antibiotic therapy are commonly cited as predisposing factors. Since the exact conditions that allow fungal colonization of the uterus are obscure, there are currently no treatments proven to offer a high likelihood of resolution, and recidivism is common. Uterine infection with fungal organisms is therefore a considerable therapeutic challenge with a poor prognosis both in terms of speed of recovery and in terms of future breeding potential, since the organisms invade deep into the endometrium where they instigate fibrotic degeneration. While both the identity of the causal organism and the duration of infection may affect the response to treatment, it is advisable to simultaneously correct any (suspected) predispositions (e.g. pneumovagina) and to treat against a potential reservoir of infection in the caudal reproductive tract (vagina and clitoral fossa). In the author’s experience, intrauterine infusion with non-specific chemicals such as 2% acetic acid or hydrogen peroxide for 1-3 days or with anti-fungals such as clotrimazole (500mg) or nystatin (1.2 million units) daily for 5-7 days yields a resolution rate of 20-30% per treatment cycle. Recently, a combination of a single treatment with 2% acetic acid followed by six consecutive days of intrauterine and intravaginal clotrimazole has yielded better results. Resolution of fungal infection is often followed by a streptococcal endometritis that also requires treatment. If initial treatment is unsuccessful, a period of rest to allow spontaneous re-establishment of a normal uterine environment can be surprisingly effective. Proceedings  of  the  South  African  Equine  Veterinary  Association  Congress  2016   12