Blood Plasma Levels of Progesterone and Oestradiol in the Dog During the Oestrous Cycle and Pregnancy

Abstract

Plasma oestradiol and progesterone levels were studied in German Shepherd and Greyhound bitches during the normal oestrous cycle, pregnancy and at parturition. The mean oestradiol level increased from approximately 7 to 13 pg/ml during the fifth week before onset of oestrus. Oestradiol stayed at this level until pro oestrus which was characterized by a steady increase to a mean peak level of about 30 pg/ml 5\p=n-\6days before oestrus. At the start of oestrus the level was approximately 12 pg/ml. A level between 10\p=n-\15pg/ml was kept during the following 10 weeks whether or not the bitch was pregnant and no change occurred at parturition. The mean progesterone level was found to be very low, around or under 1 ng/ml, until 1\p=n-\4 days after the oestradiol peak after which the level gradually increased to around 10 ng/ml at the start of oestrus. During oestrus and metoestrus or pregnancy the pattern was inconsistent. In some bitches the level gradually increased during 3\p=n-\4weeks and reached a peak value of 30\p=n-\50 ng/ml. The level then gradually decreased during 5\p=n-\6 weeks. During the first 5 weeks of the same period progesterone in other bitches fluctuated between similar maximum levels and extremely low levels. After the fifth week the pattern was the same for all bitches.In the pregnant bitches there was a significant drop of the progesterone level at parturition. The data suggest that the dog is not an ideal test animal for steroids synthetized for use in man.

Reproductive endocrine patterns in captive female and male red wolves (Canis rufus) assessed by fecal and serum hormone analysis

“…Serum hormone profiles during the periovulatory period also were similar to those reported for the gray wolf [Seal et al, 1979] and domestic dog [Edqvist et al, 1975;Concannon et al, 1977a;Wildt et al, 1979;Olson et al, 1982;Hay et al, 2000]. The preovulatory LH surge was similar in magnitude and duration (B4 days) to that reported for other canid species, and occurred on the same day as the first significant increase in mean progesterone concentrations [Seal et al, 1979;Concannon et al, 1989].…”

“…Based on fecal progestagen analysis, gestation length in the red wolf was 64-65 days and comparable to that reported in the grey wolf (60-65; [Seal et al, 1979]), maned wolf (65 days; [Velloso et al, 1998]), and domestic dog (64-66 days; [Concannon et al, 1989]). Pregnancy-specific differences in circulating steroids have not been clearly identified in the domestic dog [Smith and McDonald, 1974;Edqvist et al, 1975;Hadley, 1975;Nett et al, 1975;Austad et al, 1976;Concannon et al, 1977b;Gr. af, 1978;Reimers et al, 1978;Onclin and Verstegen, 1997], possibly because of the increased hemodilution, metabolism, and clearance associated with pregnancy [Concannon et al, 1977b].…”

Diurnal Variation of Serum Progesterone, but Not Relaxin, Prolactin, or Estradiol-17β in The Pregnant Bitch*

“…P is produced by the ovary and not by the placenta in the bitch (4,12). The regulation of P secretion appears to be similar in pregnant and pseudopregnant bitches, and is a function of the underlying reproductive cycle (2)(3)(4)(5). Concannon et al (14) recently provided pharmacological evidence that both LH and PRL are required for luteal progesterone secretion in the bitch.…”

“…However, as PRL showed no diurnal changes in concentration, it does not appear to be directly responsible for the diurnal pattern exhibited by P. (Endocrinology 127: [1057][1058][1059][1060][1061][1062][1063]1990) T HERE have been several studies of the circulating hormones in the pregnant bitch, and the daily or weekly patterns of secretion of progesterone (P), estradiol-17/3 (E2), LH, PRL, and more recently, relaxin (Rlx) have been described (e.g., Refs. [1][2][3][4][5][6][7][8][9][10][11][12]. Apart from these descriptive studies, there is relatively little information about the glandular source and regulation of hormone secretion during pregnancy in the bitch.…”

Ovariectomy during the luteal phase influences secretion of prolactin, growth hormone, and insulin-like growth factor-I in the bitch

“…In the domestic bitch the oestrous cycle is characterized by a follicular phase with spontaneous ovulation, followed by a luteal phase of about 75 days and a non-seasonal anoestrus of 2-10 months [1]. In contrast to most other mammalian www.journals.elsevierhealth.com/periodicals/the Theriogenology 66 (2006) [484][485][486][487][488][489][490] species, the bitch has a luteal phase that is comparable in duration to pregnancy [2,3].…”