This study assessed the value of ultrasonography in characterising bovine cystic ovaries and monitoring their responses to different treatments. Thirteen cows were diagnosed by ultrasonography as having luteinised ovarian cysts and seven were diagnosed as having follicular ovarian cysts. Six of the former were treated with prostaglandin, four with a progesterone intravaginal device (PRID) and three with gonadotrophin-releasing hormone (Gn-RH); five of the latter were treated with Gn-RH and two with a PRID. All the animals were re-examined by ultrasound and blood was collected for the measurement of plasma progesterone concentration at intervals until oestrus. The treatment of the luteinised cysts with prostaglandin caused marked decreases in size and plasma progesterone concentration and altered their echotexture within two to four days; oestrus occurred within three to four days. In two of the cows treated with a PRID the cysts regressed within one to two weeks but the other two cows required supplementary treatment with prostaglandin; oestrus and ovulation were observed only after the cysts collapsed. Gn-RH stimulated oestrus and ovulation within three to four days but the cysts did not collapse until much later. The treatment of the follicular cysts with Gn-RH or a PRID caused fresh ovulation and the formation of a corpus luteum but had little immediate effect upon the cyst. The plasma progesterone concentrations in some of the cows with either follicular or luteal cysts were similar on the day of treatment and were therefore of little value in differentiating the types of cyst.(ABSTRACT TRUNCATED AT 250 WORDS)
The reproductive tracts of 22 Friesian dairy cows were examined from seven to 35 days after insemination using a real time B-mode ultrasound scanner with a 7.5 MHz transducer. The earliest detection of pregnancy was at nine days when a vesicle was imaged within the lumen of the uterine horn. The early conceptus was seen at day 13 within the vesicle and these structures were followed ultrasonically until day 35. There was a sudden enlargement of the vesicle at day 19 and a heart beat was detected in the embryo at day 22. The allantois was imaged at day 23 and the amnion by day 29. The embryonic outline was clearly defined by day 33 when the body cavities could be discerned. This ability to determine pregnancy at an early stage should prove to be a useful technique in investigating the problems associated with early embryonic death in cattle.
Actinomyces pyogenes from a case of endometritis was used to study the effects of infection of the bovine embryo between days 27 and 41 of pregnancy. From 10(9) to 10(10) washed organisms were introduced into the uterine lumen of four pregnant cows. Two pregnant cows were inoculated with sterile saline and four pregnant cows were treated with cloprostenol. Embryonic death and abortion followed 29 to 144 hours after the inoculation of the live bacteria. The aborted embryos were macerated or clearly degenerating and yielded profuse pure cultures of A pyogenes. Abortion was accompanied by a sustained increase in uterine tone, opening of the cervix, presence of vaginal pus and a vulval discharge and the persistence of the corpus luteum for at least eight days after abortion. Intrauterine inoculation with saline did not affect pregnancy, but embryonic death, abortion and regression of the corpus luteum occurred 66 to 72 hours after the treatment with cloprostenol. The results suggest that A pyogenes is a primary pathogen and is capable of causing embryonic death and abortion.
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