Scintigraphic measurement of uterine clearance in normal mares and mares with recurrent endometritis

Abstract

Summary The percentage of Technetium 99m‐albumin colloid (99mTc‐μAA), a radiocolloid, cleared from the uterine lumen within 4 h of intrauterine infusion, was measured in 15 mares during 2 consecutive cycles, on Day 3 of oestrus and 48 h after ovulation. Four nulliparous (Group 1) and 4 multiparous (Group 2) mares were classified as resistant and the remaining 7 multiparous mares were classified as susceptible (Group 3) to endometritis. Mares in Groups 1 and 2 cleared more 99mTc‐μAA from their uteri than did mares in Group 3 during oestrus (P<0.01) and 48 h after ovulation (P<0.001). In the Group 1 + 2 mares, >50% of the colloid was cleared in 7 and none in the remaining mare, apparently related to lack of cervical relaxation. Mean percentage of 99mTc‐μAA cleared by Group 3 mares was negligible (<5%), but some 99mTc‐μAA was cleared by 3 of the 7 mares during 4 of the 6 studies conducted. Clearance of radiocolloid infused into the uterus of 3 reproductively normal mares during dioestrus was negligible. 99mTc‐μAA infused into the uterus did not adversely affect endometrial integrity as determined by endometrial biopsy. Mares tolerated the procedures well. We conclude that scintigraphy can be used to detect impaired mechanical clearance of the uterus: reproductively normal mares clear >50%99mTc‐μAA within 2 h of infusion whereas those susceptible to endometritis or mares with poor cervical dilatation may exhibit delayed uterine clearance.

Endometrial inflammatory markers of the early immune response in mares susceptible or resistant to persistent breeding-induced endometritis

“…The findings that susceptible mares have an altered initial inflammatory response on a gene expression level support other data describing differences in the ability to clear inflammation between resistant and susceptible mares after bacterial challenge (Troedsson & Liu 1991, Troedsson et al 1993a, LeBlanc et al 1994. Although the clinical signs differentiating resistant and susceptible mares are observed several days after insemination, to better define the pathogenesis of PBIE it is important to elucidate the timing of the uterine immune response of the resistant mare compared to the susceptible mare at a molecular level.…”

“…Also, the migration of PMNs to the uterine lumen may be hindered in the susceptible mares because the endometria of susceptible mares have more degenerative changes, and PMNs may have trouble moving through the fibrotic endometrial tissue. In addition, the uterine contractions in response to inflammation may aid in the movement of PMNs into the uterine lumen, and the migration of the PMNs may be slower in susceptible mares, as they have reduced myometrial activity (Troedsson et al 1993a, LeBlanc et al 1994. The increase in endometrial PMNs in susceptible mares may reflect longer persistence of PMN accumulation rather than differences in cellular responses and may be more a symptom than cause of prolonged inflammation.…”

“…infusion with a high dose of Escherichia coli as early as 3 h after challenge in normal diestrous mares (Christoffersen et al 2010). Uterine clearance begins as early as 30 min after infusion with radiocolloid (LeBlanc et al 1994), and myoelectrical patterns in susceptible and resistant mares differ as early as 6 h after bacterial inoculation into the uterus (Troedsson et al 1993a). Given these findings, it is possible that the critical time frame for cytokine mRNA expression as it relates to susceptibility to PBIE occurs much earlier than 24 h (as previously investigated).…”

The uterus, an organ of many roles

“…A further complication to this subject of venereal infection is the fact that some mares are more susceptible to infection than others. The conceot of the susceotible mare stems from work pedormed by Loy, 1969 andKenney et al, 1975; and has furlher expanded the clinical interest into immunology (Asbury et al, 1982;Widders et al, 1984;Cheung et al, 1985;Hansen, 1987, Watson et al, 1987;LeBlanc et al, 1991).Interest in myometrial activity (Taverne et al, 1979;Troedsson et al, 1995) and uterine drainage (fluid accumulation) (LeBlanc, 1994a(LeBlanc, , 1994b has become a recent focus of clinical interest.…”

The phagocytic function of blood-derived polymorphonuclear neutrophils after administration of dexamethasone for the modulation of post-breeding endometritis in the mare

“…While there is currently no "gold standard" for the treatment of persistent breeding-induced endometritis in the mare, mechanical removal of intraluminal uterine fluid via uterine lavage and administration of ecbolic agents continue to be the treatments of choice due to the proven efficacy and safety of these methods (Liu et al 2008). These strategies address the impaired myometrial function, which has been documented as the major predisposing factor to the accumulation of intrauterine fluid and the development of persistent endometritis in the mare (Troedsson et al 1991, LeBlanc et al 1994.…”