Tocodynamometry detects preterm labor in the bitch before luteolysis.

Preterm labor (PTL), myometrial activity, and accompanying cervical changes can lead to the loss of pregnancy via resorption or abortion before term gestation. Idiopathic PTL has no metabolic, infectious, congenital, traumatic, or toxic cause identified; however, hypoluteoidism has been hypothesized to cause PTL in the bitch, based on progesterone measurements at the time of clinical pregnancy loss. This study documents the use of tocodynamometry to detect PTL in 5 bitches; progesterone measurements in these bitches were normal for pregnancy at the time PTL was diagnosed.

Benign placental mass with fetal growth retardation in a bull mastiff.

A 4-year-old bull mastiff presented due to premature labour. The referring veterinarian elected to perform a caesarian delivery and at the time of surgery a 4×4×2 cm round, smooth, red to tan, lobulated soft mass was identified attached to the allantoic surface of the zonary placenta of one pup. Microscopically, this mass was composed of loosely arranged confluent undulating cords of polygonal to columnar epithelioid cells separated by a fine fibrovascular stroma resembling the placental labyrinth. The labyrinthine structure and epithelioid nature of the cells suggested that the mass was of trophoblastic origin. Due to the non-invasive nature of the mass and relatively low mitotic activity, this proliferative trophoblastic mass was considered to be benign. The absence of morphological features supporting malignant behaviour and the recapitulation of the normal labyrinthine architecture led to the diagnosis of a trophoblastic hamartoma. To the authors' knowledge this is the first report of a placental hamartoma in the dog.

Non-enzymatic antioxidative defence mechanisms against reactive oxygen species in bovine-retained and not-retained placenta: vitamin C and glutathione.

Vitamin C and glutathione (GSH) are water-soluble antioxidants which take part in defence mechanisms against reactive oxygen species (ROS). They may also be involved in processes of releasing/retaining bovine fetal membranes. Hence vitamin C, reduced (GSH) and oxidised (GSSG) glutathione levels were determined in retained and not-retained bovine fetal membranes in order to describe the non-enzymatic antioxidative status. Placental samples were collected immediately after spontaneous delivery or during caesarean section before term and at term, and 6 groups were formed as follows: (A) pre-term caesarean section without retained placenta; (B) pre-term caesarean section with retained placenta; (C) term caesarean section without retained placenta; (D) term caesarean section with retained placenta; (E) spontaneous delivery without retained placenta and (F) spontaneous delivery with retained placenta. Homogenates of maternal and fetal placental tissues were prepared, and vitamin C, GSH and GSSG were measured spectrophotometrically. Vitamin C levels were significantly higher in the maternal part than in the fetal part of the placenta in all groups examined. In retained placenta cases the levels were significantly lower than in control cows, except in pre-term groups. GSH concentrations were significantly higher in placentas without retention than with retention. GSSG levels showed the opposite relationship and were significantly higher in samples with retention of fetal membranes than in controls. Further experiments on antioxidative as well as oxidative status in bovine placenta are necessary.

Prophylaxis of respiratory distress syndrome in premature calves by administration of dexamethasone or a prostaglandin F2 alpha analogue to their dams before parturition.

OBJECTIVE: To investigate effects of preterm induction of calving by administration of flumethasone and dinoprost on the lecithin-to-sphingomyelin ratio in amniotic fluid and on neonatal respiratory distress after birth. ANIMALS: 45 dairy cows and their newborn calves. PROCEDURE: Amniotic fluid from 45 cows was obtained and tested between days 258 and 270 of gestation. Cows were then given flumethasone (10 mg; n = 15), dinoprost (25 mg; n = 15), or saline solution (n = 15). Thirty hours later, left flank cesarean section was performed, amniotic fluid was collected, and the calf was delivered. Blood for determination of progesterone was withdrawn at amniotic fluid sample collections and before induction of calving. Blood for analysis of pH and base deficit was collected from calves during cesarean section and repeatedly after birth. Phospholipids in amniotic fluid were measured by thin-layer chromatography, and progesterone was determined by radioimmunoassay. Base deficit and pH were measured, using a blood gas analyzer. RESULTS: Before treatments, a corpus luteum was present in all cows and the lecithin-to-sphingomyelin ratio in amniotic fluid did not differ between groups. Thirty hours after injections of flumethasone and dinoprost, progesterone concentration had decreased (P < 0.05) and the lecithin-to-sphingomyelin ratio was significantly (P < 0.05) higher than values in controls. In calves delivered after flumethasone or dinoprost treatments, the degree of acidosis was significantly (P < 0.05) less than that in controls. CONCLUSIONS: Flumethasone and dinoprost, given to pregnant cows, accelerate fetal lung maturation and improve respiratory function after birth.

[The effect of subclinical and acute ante partum acidosis in cows on the course of pregnancy with regard to the steroid hormone profile]. / Einfluss subklinischer und akuter Azidose ante partum bei Kühen auf den Graviditätsverlauf unter Berücksichtigung der Steroidhormonprofile.

Experiment 1: In a field experiment in 19 of 87 cows being in day 260-265 of pregnancy subclinical metabolic acidosis was found. The control group included 10 healthy cows in the same stage of pregnancy. Blood samples from cows of both groups were collected once daily until day 2 post partum for determination of oestrogens, progesterone and cortisol. Dystocia was found in four and retained placenta in three cows having acidosis. These cows had lower oestrogens and markedly higher cortisol and progesterone concentrations during parturition. Course of pregnancy and delivery in control cows an without any difficulties and hormonal profiles in these cows were typical. Experiment 2: On day 265 of pregnancy experimental acute acidosis was evoked in five cows and five other cows served as control. Sampling of blood was the same as in experiment 1. Acidosis caused on day 269 in two cows premature birth with retained placenta. Moreover concentrations of studied steroids were atypical. In three other cows with acidosis course of pregnancy and delivery was without any trouble. Only cortisol was increased while progesterone and oestrogen values were in agreement with concentrations of control cows. Data suggest that metabolic acidosis can cause dystocia, premature birth and retained placenta. Furthermore, acidosis clearly affects the profile of steroid hormones.

Production of premature delivery in pregnant rhesus monkeys by androstenedione infusion.

The endocrine mechanism involved in term and preterm delivery in primates, including pregnant women, are poorly understood. In the term monkey, fetal plasma androgen concentration rises to two hundred times the maternal concentration which remains unchanged. Placental conversion of androgen to estrogen results in increased maternal plasma estrogen concentration at term in both pregnant nonhuman primates and women. In the present study, continuous infusion of androstenedione to 0.8 gestation monkeys resulted in the premature occurrence of labor-type myometrial activity and increases in maternal plasma estrogen, oxytocin and amnion fibronectin concentrations similar to those measured at normal-term labor. Androstenedione induction of these normal-term biochemical and endocrine changes accompanied by fetal membrane rupture, cervical dilatation and live delivery provides a rich opportunity to study the molecular and physiological mechanisms of both term and preterm labor in primates.

ACTH-induced preterm labour in the ewe is associated with increased mRNA and protein levels of myometrial gap junction protein, connexin-43.

The myometrial gap junction protein, connexin-43, is thought to be critical to the development of synchronous, high-amplitude contractions of the myometrium during labour. The purpose of this study was to determine the relationship between the temporal expression of myometrial connexin-43 mRNA and protein, the contractile patterns of the uterus and the changes in maternal plasma oestrogen and progesterone. On day 127 chronically catheterized fetal sheep were randomized to receive either ACTH (1 microgram over 15 min every 2 h) or saline (control) infusions. Using this model, ACTH induces labour in 110 +/- 5 h and produces similar endocrine profiles and changes in myometrial activity to that of term spontaneous labour. Myometrial tissue was obtained during autopsy at: 0 h (127 days: no infusion), 72 h saline, 72 h ACTH, 120 h saline, and during ACTH-induced labour (n = 4/group). Northern analysis demonstrated a significant (P < 0.05) increase in connexin-43 transcripts during labour (2.21 +/- 0.39; mean +/- S.E.M. relative to 18S) compared with 0 h (0.67 +/- 0.17) and 72 h ACTH (0.41 +/- 0.11). Connexin-43 protein (as determined by Western analysis) showed a similar pattern to that of the transcripts. These changes in myometrial connexin-43 expression were associated with significant increases in the rate of rise of intrauterine pressure, frequency and maximum amplitude of uterine contractions and the maternal plasma oestrogen to progesterone ratio. No changes in connexin-43 expression, contractile parameters or endocrine profiles occurred in control animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Interbirth interval and duration of pregnancy in hares.

The possibility of inducing superfetation in hares by artificial insemination (AI) was investigated. AI performed on various days during the second half of gestation did not result in new pregnancies, but all ongoing pregnancies were terminated 1-4 days after AI. We suggest that copulation during the last week of pregnancy, common among captive hares, may have a similar effect to that of AI in terminating pregnancies and inducing early deliveries. Intervals between successive deliveries that are shorter than the normal duration of gestation do not necessarily indicate superfetation and this phenomenon may be rare among hares in captivity as well as in the wild.

Effects of ingestion of ponderosa pine needles by late-pregnant cows on uterine blood flow and steroid secretion.

Consumption of Ponderosa pine needles by late-pregnant beef cows results in the premature delivery of a viable calf. We have demonstrated the presence of a factor(s) in plasma from cows fed pine needles that specifically increased uterine arterial tone (i.e., decreased arterial diameter) in vitro. This study was designed to investigate changes in uterine blood flow and steroid secretion/uptake by the gravid uterus of cows fed pine needles to induce premature parturition. Sixteen beef cows were laparotomized on d 240 of gestation, and an electromagnetic blood-flow probe was placed around the uterine artery supplying the gravid horn. Cows were randomly assigned on d 250 of gestation to a control (n = 8; 8.2 kg/d of alfalfa hay) or pine needle (n = 8; 2.7 kg/d of pine needles + 5.5 kg/d of alfalfa hay) diet. Uterine blood flow was monitored, and systemic blood (uterine arterial and[or] jugular venous) and uterine venous blood samples were collected daily between 0630 and 0800, just before feeding. Five of eight cows fed pine needles calved prematurely (average day of gestation = 260.2 +/- .6) compared with cows fed the control diet, which calved on 287.6 +/- 3.4 d of gestation. Uterine blood flow in the control cows remained constant from d 250 through the day of parturition. In contrast, uterine blood flow of cows fed pine needles that calved early decreased progressively (P less than .01), declining to 25.2% of its original value by the day of parturition.(ABSTRACT TRUNCATED AT 250 WORDS)

Premature bovine parturition induced by ponderosa pine: effects of pine needles, bark and branch tips.

Three components of Ponderosa pine trees were administered via gavage to pregnant cows to determine their ability to induce premature parturition. When tips of branches, bark or needles were administered (2.7 kg/day) starting at 250 d of pregnancy, early parturition was induced in an average of 3.4, 5.0 and 9.1 d, respectively, compared to 31.8 d for water gavaged controls (P less than 0.01). Less pine material was required to induce parturition with tips and bark (9.4 and 11.2 kg/cow, respectively) than with needles (25.0 kg/cow P less than 0.05). Cows fed pine material retained fetal membranes longer after parturition; 13.0 d for needles, 10.5 d for bark and greater than 3.0 d for tips versus less than 0.5 d for controls (P less than 0.01). However, 2 of the cows fed tips died within 48 hours after parturition with fetal membranes intact and the other 2 cows fed tips became depressed, pyrexic and emaciated. They survived after extended veterinary care with antibiotic and fluid therapy. Administration of pine materials modified serum progesterone concentration profiles; there was significant elevation in progesterone 1-3 days after pine material was administered. Subsequently, pine material induced a premature decline in progesterone levels prior to parturition, which occurred more rapidly in cows fed bark and tips suggesting a dose response relationship. Pine material also modified serum cortisol concentration profiles; the main difference was a prolonged elevation in cows receiving tips. Branch tips and bark from Ponderosa pine are more potent in inducing parturition than needles.

Evaluation of histopathologic and physiologic changes in cows having premature births after consuming Ponderosa pine needles.

Premature calving, typified by early expulsion (17 to 43 days) of weak or dead calves and accompanied by retained placentas, was induced in 8 of 9 pregnant cows fed a mixture of Ponderosa pine needles and alfalfa hay. Five control cows of comparable gestation age fed only alfalfa hay maintained normal pregnancies until they were euthanatized at the time the pine needle-treated cows were producing premature calves. Serum specimens from all cows were assayed for progesterone concentration and ovaries and placentomes were examined for histopathologic changes. There were no bacterial, fungal, chlamydial, or viral agents determined to be associated with the premature births. Serum progesterone concentration in the treated cows decreased progressively and were 0.4 to 1.5 ng/ml at the time of premature calving. Histopathologic changes were evident in the placenta and corpora lutea of treated cows only. The number of binucleate trophoblastic giant cells in placentomes was less than normal and the number of necrotic luteal cells in corpora lutea was greater than normal.

Effect of intranasal oxygen administration on arterial blood gas and acid base parameters in spontaneously delivered, term induced and induced premature foals.

The effect of intranasal administration of oxygen at a flow rate of 10 litres per minute for 10 minutes, was studied in a total of 19 foals (thoroughbred and pony) aged between 0.5 and 12 hours. Arterial blood samples were collected before and after oxygen administration for the determination of paO2, paCO2, pHa and base excess. The foals were divided into three groups: five spontaneously delivered thoroughbred and pony foals (group 1), seven term induced thoroughbred foals (group 2) and seven induced premature pony foals (group 3). To examine the effect of duration of oxygen administration on blood gas values, three foals aged five to seven days received intranasal oxygen for 40 minutes and serial arterial blood samples were collected. Significant increases in paO2 values were found in group 1 and group 2 foals in response to intranasal oxygen. When the groups were compared, groups 1 and 2 had significantly higher paO2 values than group 3 foals, whether breathing air or oxygen. The duration of administration of intranasal oxygen had no significant effect on blood gas values.