诱导妊娠母猪白天分娩及其机理的研究

用氯前列烯醇对妊娠后期母猪作一次性肌注，从注射前至分娩开始，以１２小时为间隔采血，然后用放射免疫法分析血样，发现注射前血浆孕酮含量较高（１５．９５ｎｇ／ｍｌ），以后逐渐显著下降，分娩时降低到最低（５．３９ｎｇ／ｍｌ）。这说明外源性氯前列烯醇对母猪分娩前妊娠黄体有溶解作用，可导致母猪分娩提前发动。实验发现，在妊娠期１１０天、１１１天和１１２天处理母猪的白天分娩率分３１１为９０％（１８／２０）、８８．２４％（１５／１７）和７５％（１２／１６）；不同处理剂量（０．０５ｍｇ。０．１ｍｇ、０．２ｍｇ）的白天分娩率分别为８６．９６％（２０／２３）、８７．５％（１４／１６）和７８．５７％（１１／１４）；实验组的平均白天分娩率（８４．９１％，４５／５３）显著高于对照组（４５．６５％，２１／４６）；处理至分娩间隔时间平均为２４小时２４分钟。     

Infertility in the brood mare

This communication describes the methods used and results obtained with a 21-year-old Standardbred sire bred, using artificial insemination techniques, to a book of 108 mares during the period 11th September to 16th March, 1979-80. A positive pregnancy test rate of 93.5% was achieved. Those mares becoming pregnant averaged 4.6 inseminations per pregnancy (range 1-13). Barren mares, maiden mares and wet mares, irrespective of age, all achieved highly satisfactory pregnancy rates and it was noted that breeding through the January/February period improved the ultimate success rate markedly. When the official returns for the breeding season under review were returned the sire had a live foal success rate of 84%.     

Ovarian ultrasonography in the mare

Ultrasonography has become indispensable in the control of equine reproduction. Mare ovary layers are inverted with respect to other species, with the follicles and corpus luteum found inside the ovary; only large follicles protrude from the organ's surface. This renders the making of diagnoses via rectal palpation of the ovaries very difficult. Ultrasound imaging, however, provides another avenue of examination. Since its first use in 1980, the diagnostic potential of ultrasonography has greatly improved. Colour Doppler ultrasonography can even asses blood flow, allowing for much better monitoring of ovarian activity. This study discusses the use of ultrasound, and in particular colour Doppler ultrasonography, in the monitoring of mare ovarian function and disease.     

Endometrial cysts in the mare

Endometrial cysts are a contributing factor to subfertility in the mare. This article is a review of incidence, pathogenesis, clinical significance, diagnostics, and current treatments available.     

XO syndrome in the mare

Only one X chromosome was found in each of the lymphocyte metaphases studied in an infertile mare. Karyotype analysis was made with the CBG and GTG banding techniques. The most obvious clinical abnormality was gonadal hypoplasia.     

Pulmonary Maturation in Canine Foetuses From Early Pregnancy to Parturition

Development of the foetal respiratory system includes both pulmonary growth and maturation. In human medicine, a higher incidence of respiratory distress is reported in newborn males. This study aimed to identify different phases of canine foetal lung maturation throughout pregnancy, to determine the stage of pregnancy in which surfactant production begins and to compare pulmonary development of male and female foetuses. Pregnant bitches (34) were subjected to elective ovariohysterectomy and allocated into four groups, according to the stage of pregnancy: 30–40 days of pregnancy (n = 10), 41–50 days (n = 10), 51–60 days (n = 10) and bitches in the first stage of parturition (n = 4). Foetal lungs were histologically processed and evaluated by optical microscopy. The pseudoglandular phase was identified between the 35th day and 46th day of gestation; the onset of canalicular and saccular periods was observed, respectively, from the 48th day and 60th day of pregnancy. Lungs from foetuses at term were in the saccular phase; thus, the development into the alveolar period occurs in the neonatal period. The histological analyses revealed that respiratory tract development is centrifugal, from upper to lower airways. Therefore, it is possible to identify distinct development periods in different portions of the same organ. In conclusion, the saccular phase of lung development begins around 57 and 60 days of pregnancy, the period in which surfactant production is believed to occur. Male and female foetuses present similar pulmonary development from early pregnancy until parturition.     

Ultrasonography as an adjunct to pregnancy assessments in the mare

Ultrasonographic detection of pregnancy was performed in 952 Thoroughbred mares. Characteristic images were obtained between 12 and 55 days after breeding. Twins in the same uterine horn as well as twins in opposite horns were imaged, and for the first few months of gestation appeared similar to single pregnancies. Growth curves as a function of time were developed, utilizing horizontal diameters of the blastocysts versus breeding dates. Comparisons between horizontal and vertical diameters demonstrated no appreciable differences when observed as a group. Growth curves derived from twins did not differ significantly from those for single pregnancies during the period we observed them. Ultrasonographic evaluations were valuable in substantiating mechanical destruction of one of the twin blastocysts immediately following the maneuver. Uterine artifacts such as endometrial and lymphatic cysts also were visualized and portrayed. Although these structures represented a source of false-positive results, they usually could be properly identified on the basis of their morphometric and growth characteristics.     

Induced Parturition in Swine Herds

Intramuscular injections of various levels of prostaglandin F(2alpha) were administered to 116 pregnant swine in three commercial herds and the University research unit on Day 111, 112 or 113 of gestation. Sixty-three percent of the treated animals farrowed during the working day immediately following treatment. The parturition time, birth weight, litter size, number of piglets weaned, growth of the piglets to weaning and subsequent rebreeding of the dams were comparable with the expected performance in the herds. The results indicated that prostaglandin F(2alpha) in doses ranging from 5 to 12.5 mg per animal were effective for induction of parturition in a substantial proportion of the treated animals. Successful induction of parturition could reduce the farrowing interval for batches, allow more supervision of farrowing, facilitate transfer of piglets from large to small litters and generally increase efficiency in the farrowing unit. This technique could have practical application in intensive swine production units.     

Abortion due to Bacillus safensis in a mare

A 16-year-old Westphalian mare aborted a dead fetus at 7 months of gestation without prodromal signs. The chorioallantois was diffusely thickened and discoloured, with fibrinous plaques, congestion and haemorrhage. Small colonies of 1-μm, Gram-positive bacilli were scattered throughout the exudate overlying the chorionic epithelium, and within macrophages. Bacillus safensis was isolated from the fetal lungs and from a swab sample of the mare's uterus. This strain represents the first case of a B. safensis-associated equine abortion and the first case of any infection caused by this bacterium.