Common Peripartum Problems in the Mare

Reproductive problems in the perinatal period can adversely affect a mare's future fertility or, worse, may be life threatening to her or her foal. A number of abnormalities can occur, including uterine torsion, uterine artery or uterine hemorrhage, retained fetal membranes, metritis, rectovaginal injuries, and necrotic vaginitis. Because hemorrhage, retained placenta, metritis, and necrotic vaginitis can happen after a normal delivery or after dystocia, all mares should be monitored closely in the first days after parturition for signs of lethargy, depression, colic, sore feet, or anorexia. Methods for diagnosing, managing, and treating these conditions and the possible complications are discussed.     

Some Aspects of Twin-gestation in the Mare

A study has been made of 44 cases of twin pregnancy in mares. The fetuses, foals, fetal membranes and blood groups of parents and foals were examined in order to determine the incidence of chorio-vascular anastomosis, blood chimaerism and freemartinism.

All of the twins proved to be dizygotic and 33 of the 34 pregnancies were bicornual. Fusion of the chorion was seen in 14 of 22 placentas and macroscopic choriovascular bridges were observed in five of these, although blood chimaerism was diagnosed in 11 of 25 cases (44 per cent) examined. This would indicate a high incidence of microchoriovascular anastomosis. The fetal female genital organs of four heterosexual twins were found to be anatomically and histologically normal at autopsy despite the existence of blood chimaerism. Five other sexvalley mature mares born as heterosexual twins with chimaerism all had normal genital organs and estrus cycles and one of these has since become pregnant. The important interspecies differences with respect to the incidence and degree of choriovascular anastomosis and freemartinism are stressed and suggestions for a plausible explanation were advanced.

     

Drug-metabolizing Enzymes in the Placenta and Foetus of Camel and Sheep

Contents The activities of cytochrome P-450 and the P-450 dependent aminopyrine -N-demethylase and aniline 4-hydroxylase (Phase I, drugmetabolizing enzymes) and UDP-glucurony-l-transferase (a Phase II drug-metabolizing enzyme) have been measured in vitro in the placenta and liver of camels and sheep during pregnancy. The placenta of late pregnancy of both species produced 50% of the activity in maternal liver of phase I drug-metabolizing enzymes. The rate of O-aminophenol glucuronide was low both in placenta and foetal liver. It is suggested that close to term the placenta and foetal liver are capable of metabolizing drugs by P-450 mediated phase I reactions. Inhalt: Arzneimittel-metabolisierende Enzyme von Plazenta und Fötus bei Kamel und Schaf Während der Trächtigkeit wurde die Aktivität der Cytochrom P-450 abhängigen Aminophyrine -N-Demethylase, Anilin 4-Hydroxylase (Phase I metabolisierendes Enzym) und der UDP-Glucuronyl-1 Transferase (Phase II metabolisierendes Enzym) unter in vitro Bedingungen in Plazenta- und Lebergewebe von Kamelen und Schafen gemessen. In beiden Tierarten produzierte die Plazenta während der späten Trächtigkeit 50% der Aktivität, wie sie die mütterliche Plazenta der “Phase I—Enzyme” produziert. Die O-Aminophenol Glucuronide waren dagegen gering in Plazenta und fetaler Leber. Es wird angenommen, daβ die Plazenta und die fetale Leber kurz vor der Geburt in der Lage sind, Arzneimittel durch die Cytochrom P-450 abhängige Phase I-Reaktionen zu metabolisieren.     

Ovarian Teratoma in a Mare

During a routine trip to a horse slaughterhouse, we found bilateral ovarian teratoma. Macroscopic findings were confirmed by the presence of hair, bones, and cartilage. Under microscopy, these tumors had mature foreign tissues as stratified squamous and respiratory epithelia, sebaceous and sweat glands, as well as follicular endocrine cells, inflammatory cells, hepatocytes, and hyaline cartilage.     

Oviductal Adenoma in a Mare

A 10-year-old Rocky Mountain Saddle Horse mare was initially presented for erratic estrous cycles, infertility, and an enlarged ovary. The initial differential diagnosis list comprised neoplastic and nonneoplastic ovarian conditions. The primary differential diagnosis of granulosa cell tumor was deemed less likely because of clinical findings and laboratory results. Because of the chronic nature and apparent infertility resulting from the abnormal ovary, surgery was elected to remove the affected ovary. Exploratory laparotomy confirmed the presence of the enlarged ovary; however, a larger oviductal tumor was discovered. Both the ovary and tumor were removed and the mare recovered uneventfully. The mare cycled normally, conceived, delivered a healthy foal, and is currently in late gestation with her second pregnancy.     

Uterine Prolapse in a Mare

A prolapsed uterus in a mare and the techniques to successfully replace the organ and prevent complications such as shock, laminitis and metritis are described.