Ascending placentitis in the mare: A review

Ascending placentitis is a condition that occurs late in pregnancy when bacteria enter the sterile uterus from the lower reproductive tract. It leads to abortion or the birth of premature and weakened foals. Early detection and treatment of this condition is vital for ensuring the production of a viable foal.Mares with ascending placentitis often present in late term pregnancy with signs of premature udder development and premature lactation. There may be a vulvar discharge. Early detection of placental problems is possible using trans-abdominal or trans-rectal ultrasonography. Hormones such as progesterone and relaxin may be measured as indicators of foetal stress and placental failure. Postpartum foetal membranes may be thickened and contain a fibronecrotic exudate. The region most affected is the cervical star. Definitive diagnosis of ascending placentitis is by histopathological examination of the chorioallantoic membrane.Ideal treatment strategies are aimed at curing the infection and prolonging the pregnancy to as close to term as possible and consist of anti-microbials, anti-inflammatories and hormonal support.Swabs are taken from affected mares to determine antibiotic sensitivity and to aid in treatment of foals born from these mares which are at risk of becoming septic. If detected early enough, the chances of producing a viable foal are greatly increased.     

Removal by laparoscopic partial ovariohysterectomy of a uterine leiomyoma assumed to have caused fetal death in a mare

A 13‐year‐old pluriparous Dutch Warmblood mare presented to Utrecht University's Department of Equine Sciences 4 weeks after suspected abortion at 3.5 months gestation, to investigate the nature of a uterine mass and persistent vulval discharge. Transrectal ultrasonographic examination revealed copious flocculent fluid and fetal remnants within the uterus and a 5–6 cm heterogenous mass in the uterine wall at the tip of the right horn. Expulsion of fetal parts and resolution of the coexisting endometritis were effected by a combination of repeated PGF_2a analogue injections to induce oestrus, application of PGE₂ gel to aid cervical relaxation, and daily uterine lavage and antibiotic instillation. The presence of the mass in the uterine wall was confirmed by hysteroscopy and the suspected tumour subsequently removed by partial laparoscopic ovariohysterectomy under standing sedation and local anaesthesia. The histological appearance of the tumour was consistent with a leiomyoma or moderately malignant leiomyosarcoma. Although a follow‐up examination 6 months post surgery revealed uncomplicated healing of the uterus, the owner decided to retire the mare from breeding. Uterine neoplasia is an extremely unusual cause of fetal death in the mare but, in the present case, laparoscopic partial ovariohysterectomy proved a promising, minimally invasive technique for salvaging sufficient uterus to make subsequent breeding a realistic proposition.     

Hand-assisted laparoscopic ovariohysterectomy in the mare

OBJECTIVE: To develop a minimally invasive, hand-assisted laparoscopic ovariohysterectomy (HALS-OHE) technique in the mare and to evaluate safety and any associated complications. STUDY DESIGN: Experimental study. ANIMALS: Eight, 11-24-year-old mares with anatomically normal urogenital tracts. METHODS: The surgical technique was developed in 2 non-survival mares and subsequently evaluated in 6 survival procedures. Food was withheld for 48 hours, then mares were anesthetized and positioned in dorsal recumbency for laparoscopic surgery. A hand access device (Omniport) was placed followed by 4 laparoscopic portals. Transection of the ovarian pedicles and broad ligaments was achieved using a combination of a laparoscopic stapling instrument (Endo GIA II), an ultrasonically activated instrument (Harmonic Scalpel), and endoscopic clips (Endo Clip II ML). The genital tract was exteriorized through the laparotomy, and the uterus transected and sutured in a conventional pattern. Horses were evaluated through postoperative day 14 when a necropsy was performed. RESULTS: Four mares recuperated well after surgery, 1 mare was euthanatized because of bilateral femur fracture during anesthetic recovery, and another developed severe pleuropneumonia. At necropsy all but 1 abdominal incision was healing routinely. One mare had abscessed along the celiotomy incision and developed visceral adhesions. Uncomplicated healing of transected mesovarial, mesometrial, and uterine remnants was observed. CONCLUSIONS: Ovariohysterectomy in horses can be accomplished using HALS technique. CLINICAL RELEVANCE: HALS-OHE technique represents a minimally invasive and technically feasible alternative for conventional OHE. Careful patient selection and preparation may reduce the complications observed. The HALS technique may be useful in other laparoscopic surgical procedures.     

A review of fungal endometritis in the mare

Fungal endometritis is a relatively rare cause of infertility in the mare, accounting for only 1–5% of all cases of endometritis. However, it remains a challenge to the clinician due to difficulties in diagnosing and effectively treating affected mares, resulting in a high rate of recurrence and a guarded prognosis for ongoing fertility. Often occurring as an opportunistic infection, the most common causes of fungal endometritis in the mare are yeasts (Candida spp.) and moulds with septated hyphae (Aspergillus spp.). Early detection and identification of the causative agent are vital when choosing appropriate treatment as sensitivities to commonly used antifungals vary significantly. Assessing in vitro sensitivity for each isolate is accordingly recommended. Treatment of mares with fungal endometritis is multifaceted and includes; correction of any anatomical defects, uterine lavage and systemic and/or intrauterine infusion of antifungals. Concurrent bacterial infection is common so anticipation and subsequent treatment of bacterial endometritis is also often required.     

The effects of endometrial damage on placental and fetal development in a mare

A 13-year-old ex-polo pony maiden mare with an extensively damaged endometrium was initially used as an embryo donor in a research herd. Embryos recovered from the mare were of normal morphology and size. Subsequently, the mare was inseminated and left pregnant. Early conceptus development was normal and she foaled a small (22 kg) but healthy filly after a gestation of 360 days. Examination of the placenta showed that development of the microcotyledons accurately reflected the damage to the uterus. Plasma progestagen profiles throughout gestation also provided evidence for placental pathology and fetal stress.     

Surgical resection of a dysgerminoma in a mare

A mare was referred for further evaluation of a mass found in the left caudal abdomen during a routine postpartum reproductive palpation. The mare was clinically normal with no history of health problems. Ultrasonographic examination of the mass confirmed its presence, but the origin of the mass could not be accurately determined. Routine haematology and serum biochemistry results were within normal limits. The mare was initially treated conservatively with antibiotics, but the mass continued to increase in size, so it was surgically excised. The mass involved the left ovary. The mare showed transient abdominal pain after surgery, but developed no other complications and was in foal 7 months later. On histology, the mass was diagnosed as a dysgerminoma, a rare ovarian tumour of germ cell origin.     

Prepubic tendon rupture in the mare

The following article discusses the clinical appearance, diagnosis, management and prognosis of abdominal wall tearing and prepubic tendon (PPT) ruptures of mares.     

Birth of live triplets in a mare

An 11‐year‐old American Buckskin mare gave birth to live triplets unattended at approximately 300 days gestation. All foals were small and dysmature, requiring intensive care. The smallest foal died 4 days after admission, the second was subjected to euthanasia 24 days after admission due to poor healing of a third metatarsal fracture. The remaining foal survived to discharge and was considered small but otherwise normal at age one year.     

Influence of topical dexamethasone applications on insulin, glucose, thyroid hormone and cortisol levels in dogs

The influence of two topical dexamethasone applications (dermal and ototopical) on plasma insulin, glucose, thyroid hormone and cortisol levels was investigated in beagle dogs. Both treatments significantly decreased basal cortisol values, associated with exaggerated rise in insulin (∼50%), together with unchanged serum glucose levels. Dermal dexamethasone quickly decreased plasma thyroxin (T₄) levels; whereas dexamethasone in ear drops gradually inhibited time-dependently T₄ release (18–50%). Both formulations blunted plasma triiodothyronine (T₃) levels but the response induced by dermal dexamethasone was stronger than by dexamethasone ear drops. Upon drug withdrawal, insulin secretion returned to baseline a week after treatment cessation, while cortisol, T₄ and T₃ levels did not reach baseline values. These results suggest that topical glucocorticoids unexpectedly trigger secondary hypothyroidism with concomitant suppression of hypothalamic–pituitary–adrenal axis but sensitize the endocrine pancreas, thus, their application needs careful evaluation for surprisingly different effects on endocrine stress axis activity.     

The uterus and early pregnancy failure in the mare

The environment the equine conceptus finds itself in when it arrives in the uterus some 6 days after ovulation will determine if it will thrive or die. The uterus will be its home for approximately the next 11 months and as such it needs to both coordinate the growth of the placenta and ensure there is enough nourishment passing to this organ for the fetus to develop normally. The trophoblast, endometrium, maternal ovaries and, later in pregnancy, the fetal gonads, all play roles in the hormonal changes that orchestrate these events. Although failures of these processes later in pregnancy can have catastrophic effects for the fetus, it is in early gestation that the foundations for a successful pregnancy are laid. This paper therefore concentrates on some of the noninfectious influences the uterus may have on survival of the young conceptus.     

Gastric and small intestinal ileus as a cause of acute colic in the post parturient mare

REASONS FOR PERFORMING STUDY: Ileus (functional obstruction of aboral gastrointestinal transit) is an uncommon cause of gastrointestinal dysfunction and colic in the horse. A number of specific conditions have been previously reported in association with ileus. This report describes the recognition of primary gastric and small intestinal ileus of undetermined cause in a series of post parturient mares. OBJECTIVES: To describe the clinical features, treatment and outcome of a series of episodes of primary gastric and small intestinal ileus. METHODS: A retrospective study was performed of colic episodes seen in an equine practice in Newmarket, UK over a 6 year period (2002-2007). RESULTS: Seventeen episodes of gastric and small intestinal ileus were identified, which occurred in 15 horses. All episodes occurred in post parturient mares. No previously reported cause of ileus was identified in any of the episodes. Fifteen of the 17 episodes received medical treatment (medical support and nasogastric decompression) and, in addition, surgical decompression was performed in 9 episodes. Two mares were subjected to euthanasia before treatment due to the presence of gastric rupture and the remaining 13 mares survived with a follow-up period of at least 10 months. Two mares suffered a further episode of gastric and small intestinal ileus, one 4 days and the other 2 years after the initial episode. CONCLUSIONS: Gastric and small intestinal ileus of, as yet, unknown aetiology appears to be a potential cause of acute colic in the post parturient mare. The outcome following treatment by decompression is good.     

Malignant fibrous histiocytoma of the mammary gland in a mare

Mammary tumours are uncommon in mares. Sarcomas of the breast account for less than 1% of all human primary malignancies and, among these types of tumours, malignant fibrous histiocytoma (MFH) is very rare. This report describes a 6‐year‐old uniparous Paint mare that was presented for investigation of right mammary gland enlargement of 3 weeks' duration. The clinical and histopathological findings in this mare with malignant fibrous histiocytoma of the mammary gland as well as complications of bilateral mastectomy are detailed. At one year follow‐up there were no clinical signs of recurrence.     

Monitoring of the mare during the perinatal period at the clinic and in the stable

Complications in late gestation are challenging problems for the equine clinician and are causes of considerable distress to owners. Health problems in a pregnant mare in each stage of gestation can adversely affect the pregnancy. It is important to obtain a thorough history and perform a detailed and systematic examination of the pregnant mare so that the mare may be classified as normal or high-risk. However, even after a thorough examination, practitioners may face problems with the interpretation and assessment of risk. Normal mares should foal in the stable or pasture. Mares classified as having a high-risk pregnancy need to be monitored precisely for signs of oncoming foaling with attendance of trained personnel when labour begins. A valuable method for monitoring of the high-risk mare is assessing fetoplacental well-being. Fetoplacental well-being is most accurately assessed with ultrasonography as well as several available hormone profiles. We are proposing our scoring system of the mare's health, which may be useful in the assessment of risk during pregnancy and help clinicians to decide whether sending the mare to the clinic is reasonable or unnecessary.     

Factors influencing equine chorionic gonadotrophin production in the mare

Reasons for performing study: An opportunity to monitor equine chorionic gonadotrophin (eCG) production during 61 pregnancies in 25 Thoroughbred mares mated to the same Thoroughbred stallion was utilised in order to further knowledge regarding factors involved in the production of this hormone. Objectives: To examine the effects of maternal body condition, exercise and parity on eCG production. Methods: In the first experiment, maiden mares were fed either a moderate (n = 9) or an excessive (n = 10) food intake throughout gestation. In the second experiment, 5 mares were exercised daily during pregnancy and eCG production rates were compared to 5 nonexercised mares. In the third experiment, eCG profiles were compared in 9 mares during 3 successive pregnancies. Equine chorionic gonadotrophin secretion was assessed as area under the curve (AUC), peak serum concentration, timing of the peak and the rate of decline. In addition, a mean eCG profile of 61 pregnancies was created to provide means and ranges for the above parameters. Results: In Experiment 1, eCG production was significantly higher in moderately rather than excessively fed mares in terms of AUC and peak eCG concentrations. In Experiment 2, the mean AUC did not differ between exercised and nonexercised animals but mean eCG concentrations were significantly higher in nonexercised mares between Days 60 and 90 of gestation. In Experiment 3, eCG became undetectable significantly earlier in gestation in the third parity. The mean eCG profile of 61 pregnancies showed a peak of 64.5 ± 3.7 iu/ml at 62.4 ± 1.0 days after ovulation and was undetectable by 134.1 ± 1.7 days. Peak eCG levels reduced by 50% 22.6 ± 1.13 days. Conclusions: Some of the factors examined clearly influenced eCG production rate, the secretion of this hormone and its rate of disappearance from the blood. Potential relevance: The results provide insights into some factors that govern the production of the placental gonadotrophin, eCG.     

The effects of an advanced uterine environment on embryonic survival in the mare

Reasons for performing the study: During embryo transfer (ET) the equine embryo can tolerate a wide degree of negative asynchrony but positive asynchrony of >2 days usually results in embryonic death. There is still confusion over whether this is due to the inability of the embryo to induce luteostasis or to an inappropriate uterine environment. Objectives: To assess embryo survival and development in an advanced uterine environment. Hypothesis: Embryo–uterine asynchrony, not the embryo's inability to induce luteostasis, is responsible for embryonic death in recipient mares with a >2 days chronologically advanced uterus. Methods: Experiment 1: Thirteen Day 7 embryos were transferred to the uteri of recipient mares with luteal prolongation, occasioned by manual crushing of their own conceptus, such that donor–recipient asynchrony was between +13 and +49 days. Experiment 2: Day 7 embryos were transferred to recipient mares carrying their own conceptus at Days 18 (n = 2), 15 (n = 2), 14 (n = 4), 12 (n = 4) or 11 (n = 4) of gestation. In addition, Day 8 embryos were transferred to 4 pregnant recipient mares on Day 11 of gestation. Results: No pregnancies resulted following transfer of Day 7 embryos to recipients in prolonged dioestrus with asynchronies between +13 and +49 days. However, the use of early pregnant mares as recipients resulted in 5/20 (25%) twin pregnancies, 4 of which came from the transfer of a Day 8 embryo to a Day 11 recipient. All transferred embryos showed retarded growth, with death occurring in 4/5 (80%). Conclusions and potential relevance: The results emphasise the importance of an appropriate uterine environment for embryo growth and the inability of equine embryos to survive transfer to a uterus >2 days advanced even when luteostasis is achieved. It is possible that in normal, non‐ET equine pregnancy, embryo–uterine asynchrony may account for some cases of embryonic death.     

Surgical treatment of a mammary gland comedocarcinoma in an Arabian mare: Post-operative management,and histopathological and immunohistochemical features

A lactating 20-year-old, brown, Arabian mare, weighing about 300 kg, presented for bleeding from one teat and severe swelling of the entire mammary gland. The mare had untreated mastitis 10 months before. Consequently, a gangrenous teat developed after chronic bloody and purulent discharges. The teat was removed surgically by the field veterinarian. At that time, the mammary gland increased in size. Bloody and purulent discharges restarted 10 days previously. Under general anaesthesia, the entire mammary gland was removed. Comedocarcinoma was diagnosed by histopathological assessment. Immunohistochemical staining was performed for pan-cytokeratin and vimentin. Microscopic examination of immunohistochemical stained slides revealed expression of pan-cytokeratin. In conclusion, this report describes clinical, macroscopic, histopathological and immunohistochemical characteristics of comedocarcinoma that did not metastasise to regional lymph nodes. Reports in the field of equine oncology contribute to improved general knowledge in equine medicine, contributing to better diagnosis and treatment.     

Persistent endometrial cups in the same mare in two successive pregnancies

We report upon an ageing Thoroughbred mare which showed remarkably similar and abnormally prolonged profiles of equine Chorionic Gonadotrophin (eCG) in her bloodstream during successive pregnancies sired by the same stallion. The first pregnancy was aborted at Day 75 after ovulation in conjunction with a precipitous decline in eCG concentrations which occurred immediately after the peak level had been reached. The second pregnancy, which proceeded safely to term, also involved a similar sharp fall in eCG concentrations after attainment of the peak values. Possible causes of the extended lifespan of the eCG‐secreting endometrial cups in this animal are discussed.     

Complications associated with the presence of two intrauterine glass balls used for oestrus suppression in a mare

This report describes the identification and removal of 2 glass balls, both of which had fragmented, from the uterus of a mare. The glass balls had been placed into the uterine lumen to prolong function of the corpus luteum for suppression of oestrous behaviour. This report adds to a growing body of evidence that severe complications can result from the use of intrauterine glass balls for oestrus suppression in mares, particularly if they are retained for a prolonged time.