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Biomedical subjects

B van Haaften

Publications and source records attributed to B van Haaften.

11 recordsLinked to original sources
PubMed1999

Concurrent pulsatile secretion of luteinizing hormone and follicle-stimulating hormone during different phases of the estrous cycle and anestrus in beagle bitches.

The 6-h secretory profiles of LH and FSH and the possible concordance between the episodic release of LH and FSH were studied in 6 beagle bitches during early, mid-, and late anestrus and during the follicular and luteal phases of the estrous cycle. Plasma samples were obtained at 10-min intervals via jugular venipuncture. In all stages of anestrus and in the luteal phase, FSH and LH secretion was pulsatile. All FSH pulses coincided with LH pulses. However, the mean duration of the FSH pulse (115 min) was significantly longer than that of the LH pulse (72 min). The basal plasma LH concentration was low compared with the maximum peak levels, whereas FSH pulses were characterized by relatively low peaks compared with the basal levels. In contrast to the basal plasma LH levels and the area under the curve (AUC) for LH, the basal plasma FSH levels and the AUC for FSH increased significantly as anestrus progressed. During the follicular phase, the secretory pattern of LH was characterized by frequent increases of short duration. During this phase, the basal plasma FSH concentration was relatively low, whereas the basal plasma LH level was high in comparison with that in the other phases of the estrous cycle. The luteal phase was characterized by an increased frequency of LH pulses, a shorter duration of the LH peaks, and a tendency to a lower amplitude of both LH and FSH peaks compared with values observed during anestrus. It is concluded that in the bitch, FSH and LH pulses are released in concordance and that progression from early to late anestrus is associated with an increase in basal plasma FSH concentration without a concomitant rise in basal plasma LH concentrations. The latter suggests that in the bitch an increase in circulating FSH should be considered to be a critical event required for the initiation of ovarian folliculogenesis and consequently for the termination of anestrus.

Anestrus↗
PubMed1999

Bromocriptine-induced premature oestrus is associated with changes in the pulsatile secretion pattern of follicle-stimulating hormone in beagle bitches.

The secretory profiles of LH and FSH were investigated before and during the administration of bromocriptine in six beagle bitches. Plasma samples were obtained via jugular venepuncture at 10 min intervals for 6 h every 2 weeks until the next ovulation. Bromocriptine treatment was started 100 days after ovulation. Both before and after bromocriptine treatment, LH and FSH pulses occurred together. The mean duration of the FSH pulse (120 min) was significantly longer than that of the LH pulse (80 min). The interoestrous interval in the bitches treated with bromocriptine was significantly shorter than that of the preceding cycle (160 +/- 3 versus 206 +/- 24 days). The mean basal plasma FSH concentration (7.4 +/- 0.6 versus 6.1 +/- 0.7 iu l-1) and the mean area under the curve for FSH (46.6 +/- 4.7 versus 40.4 +/- 4.4 iu l-1 in 6 h) increased significantly after the start of the bromocriptine treatment. In contrast, the differences in mean basal plasma LH concentration (2.1 +/- 0.2 versus 2.0 +/- 0.2 micrograms l-1) and the mean area under the curve for LH (19.0 +/- 3.1 versus 19.5 +/- 2.5 micrograms l-1 in 6 h) between the day before and 14 days after the start of the bromocriptine treatment were not significant. Bromocriptine administration also lowered the mean amplitude of the FSH pulse and shortened the mean duration of the FSH pulse, without influencing the LH pulse. In addition to demonstrating the concurrent pulsatile secretion of LH and FSH, the results of the present study demonstrate that the bromocriptine-induced shortening of the interoestrous interval in the bitch is associated with an increase in plasma FSH concentration without a concomitant increase in plasma LH concentration. This finding indicates that treatment with the dopamine agonist bromocriptine increase plasma FSH to a concentration that results in the enhancement of follicle development.

Analysis of Variance↗
PubMed1994

Increasing sensitivity of the pituitary to GnRH from early to late anoestrus in the beagle bitch.

The sensitivity of the pituitary to GnRH in early and late anoestrus and the indirect response of the ovary were investigated in six adult beagle bitches. Plasma concentrations of LH and oestradiol were determined after i.v. injection of graded doses of GnRH (0, 0.01, 0.1, 1, 10 and 100 micrograms kg-1). The responses were measured by the LH and oestradiol concentration profiles over time. The responses of LH and oestradiol were significantly dose dependent (P = 0.002 and P < 0.001, respectively). The responses of LH and oestradiol were significantly higher (P = 0.02 and P = 0.001, respectively) in late anoestrus than in early anoestrus. The responses of LH and the responses of oestradiol were positively correlated (r = 0.97, P = 0.001). It is concluded that during the course of anoestrus in the bitch pituitary sensitivity to GnRH increases while the ovary responds accordingly.

Anestrus↗
PubMed1993

Influence of litter size and breed on variation in length of gestation in the dog.

The variation in the length of gestation, the period from mating until parturition, was studied in 77 dogs of different breeds; the time for mating was determined by measuring peripheral blood progesterone levels. The mean length of gestation was 62.1 +/- 0.2 (S.E.M.) days, with a variation of 11 days. The number of pups appeared to influence the length of gestation. Length of gestation was negatively correlated (r = -0.96, P < 0.001, n = 44) with litter size in litters with 7 or fewer pups. The intra-breed variation in length of gestation in the five breeds represented by five or more bitches was 3-6 days. The mean gestation of Alsatians (60.1 +/- 0.5, n = 9) was shorter (P < 0.005) than that of the other breeds combined (62.3 +/- 0.3, n = 68). The primiparous/multiparous status of the bitch did not influence the length of gestation.

Animals↗
PubMed1992

[Fertility problems in the bitch].

A short review of the oestrous cycle is given, followed by a more detailed look at fertility problems caused by husbandry aspects, anatomical abnormalities, hormonal disturbances and infectious aetiologies. One of the principal causes of fertility problems appears to be mating at an inappropriate time. The ovulation period and therefore the correct time of mating can however, be defined by measuring progesterone levels in peripheral blood three times a week. Vaginoscopy can also be used for this purpose, but is a subjective and less reliable method. Sterility is normally the single symptom of cystic endometrial hyperplasia(-mucometra). This probable major cause of sterility can sometimes be diagnosed with echoscopy but sometimes only during laparotomy. Additionally, hormonal disturbances can precipitate problems such as a persistent (pro-)oestrus, a split heat, or an abnormally long interoestrous interval. Bromocriptine, 15-20 micrograms/kg body-weight, twice daily orally, can be used to induce oestrus if no obvious abnormalities are diagnosed. Attention is paid to fertility problems with an infectious aetiology, such as herpes virus or Brucella canis. A vaginitis or abnormal bacterial growth in the vagina can also influence fertility. Unfortunately, little is known about bacterial growth in the vagina in relation to fertility problems. More research is needed in this field.

Animals↗
PubMed1989

Timing the mating of dogs on the basis of blood progesterone concentration.

The optimal time for mating bitches was determined by measuring the progesterone concentration in peripheral blood three times a week after the start of vulval bleeding. Of 104 bitches with reduced fertility 81 (78 per cent) became pregnant and of 112 bitches with normal fertility 105 (94 per cent) became pregnant. Of 121 bitches mated once, 102 (84 per cent) became pregnant, and of 95 bitches mated more than once, 84 (88 per cent) became pregnant. The mean (+/- sd) interval between the start of vulval bleeding and the optimal time for mating in 88 bitches was 11.8 +/- 3.1 days. The blood progesterone concentration appears to be an excellent indicator of the best time for mating, particularly in bitches with reduced fertility.

Animals↗
PubMed1989

[The optimal service period in bitches].

The fertile period in bitches as estimated from the findings reported in the literature is discussed. Fertile periods of oocytes and spermatozoa are examined extensively. The period of ovulation is found to be more closely associated with hormonal changes than it is with symptoms of oestrus. This period occurs when the concentration of progesterone in the blood increases to a level higher than (16 nmol/l). Service one and a half days after the ovulation period results in high pregnancy rates.

Animals↗
PubMed1989

[Pyometra in an ovariectomized cat following treatment with proligestone].

A nine-year-old cat was presented for a purulent vaginal discharge which had been present for five months. She had been ovariectomised at the age of one; for the last two years she was treated with proligestone because of a dermatological condition. A pyometra was found to be present on laparotomy.

Animals↗