Estradiol bezonate



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Estradiol bezonate

  • Estradiol bezonate

    • after mating
  • Progesterone receptor antagonist: Mifepristone(RU486), Aglepristone

    • mid-gestation
  • Glucocorticoid: Dexamethasone



PGF2: Dinoprost, Cloprostenol

  • PGF2: Dinoprost, Cloprostenol

    • mid- and late gestation
  • Dopamine agonist: Cabergoline, Bromocryptine

    • mid- and late gestation


Risk after administration of estrogen

  • Risk after administration of estrogen

  • Clinically, > 60% bitches after an unwanted mating are not pregnant Feldman et al. 1993



Estrogen prolongs the ovicduct transport time and tightens the utero-tubular junction, resulting in implantation failure or embryonic death.

  • Estrogen prolongs the ovicduct transport time and tightens the utero-tubular junction, resulting in implantation failure or embryonic death.

  • 0.01 mg/kg im or sc

  • repeated injection at 3rd, 5th and 7th day after mating

  • 0.1-3 mg/kg for one injection within 4 days of mating?







Aglepristone is a safe, reliable and effective abortifacient during mid-gestation.

  • Aglepristone is a safe, reliable and effective abortifacient during mid-gestation.

  • The only side-effect of treatment was some mucoid vaginal discharge in the 1st week.

  • Aglepristone do not impair future fertility? (but only 1/6 bred later)





Side effects: polydipsia, polyuria, vaginal discharge, restlessness, anorexia or vomiting

  • Side effects: polydipsia, polyuria, vaginal discharge, restlessness, anorexia or vomiting

  • 20 bitches were mated and had normal pregnancies and normal litters.

  • Wanke et al. 1997



- more resistant to the luteolytic effect of PGF2 and susceptible to its deleterious side effects (→ atropine 50 ug/kg, im)

  • - more resistant to the luteolytic effect of PGF2 and susceptible to its deleterious side effects (→ atropine 50 ug/kg, im)

  • - the narrow margin between a LD50(5 mg/kg, 2-12 hrs after inj.) and therapeutic one

  • - side effects such as vomiting, diarrhea, pupil dilation, hyperpnoea, salivation, urination, anxiety and ataxia





The rapidly developing CL during the early luteal phase are more resistant to the luteolytic effects of PGF2 than are fully developed CL after 25-30 days.

  • The rapidly developing CL during the early luteal phase are more resistant to the luteolytic effects of PGF2 than are fully developed CL after 25-30 days.

  • Even with 250-400 ug/kg, abortive efficacy is dependent on an injection frequency greater than sid.

  • - repeated administration with low to modest dose for 4-10 days









All dogs aborted all fetuses within 9 days of beginning treatment.

  • All dogs aborted all fetuses within 9 days of beginning treatment.

  • Plasma progesterone concentration  2.0 ng/ml would result in termination of pregnancy in bitches.

  • Hospitalization is recommended to allow observation of the bitch and to avoid having the owner witness the abortion process.



Prolactin, interacting with lipoproteins to enhance P4 production in the luteal cells, is one of the important luteotropic hormones in pregnant dogs, especially in the 2nd half of pregnancy.

  • Prolactin, interacting with lipoproteins to enhance P4 production in the luteal cells, is one of the important luteotropic hormones in pregnant dogs, especially in the 2nd half of pregnancy.

  • Concannon et al. 1987 Anti-prolactin agents, such as dopamine agonists, have been used to induce abortion, from 30-40 days after LH surge.

  • Wichtel et al. 1990







The CL of the bitch are not sufficiently sensitive to the luteolytic effect of cabergoline or bromocriptine during the early to mid stage of gestation.

  • The CL of the bitch are not sufficiently sensitive to the luteolytic effect of cabergoline or bromocriptine during the early to mid stage of gestation.

  • The administration of cabergoline or bromocriptine has few side effects and may be preferable over the use of PGF2.



Recently, a treatment combining reduced doses of PGF2 (25 ug/kg → 2.5 or 1 ug/kg once daily) and a dopamine agonist which inhibits pituitary prolacin secretion was shown to terminate early pregnancy.

  • Recently, a treatment combining reduced doses of PGF2 (25 ug/kg → 2.5 or 1 ug/kg once daily) and a dopamine agonist which inhibits pituitary prolacin secretion was shown to terminate early pregnancy.

  • Onclin & Verstegen 1996



The regression of the CL is achieved directly by the PGF2 and indirectly by the carbergoline by withdrawing its main luteotropic support, prolactin.

  • The regression of the CL is achieved directly by the PGF2 and indirectly by the carbergoline by withdrawing its main luteotropic support, prolactin.

  • Okkens et al. 1990









The start treatment in the early pregnancy: Day 25 after the 1st mating; a mean of 28 days after the LH surge.

  • The start treatment in the early pregnancy: Day 25 after the 1st mating; a mean of 28 days after the LH surge.

    • close to the earlest time at which pregnancy can be diagnosed by palpation or by ultrasound
    • treatment at this time terminating pregnancy by resorption








A reduced interestrus interval of treated dogs suggests that inhibiting circulating prolactin, combined with direct luteolysis by PGF2 , may release the inhibitory mechanisms responsible for prolonging the obligatory anestrus phase of a dog’s estrus cycle.

  • A reduced interestrus interval of treated dogs suggests that inhibiting circulating prolactin, combined with direct luteolysis by PGF2 , may release the inhibitory mechanisms responsible for prolonging the obligatory anestrus phase of a dog’s estrus cycle.



Advantage:

  • Advantage:

    • safe for the bitch
    • terminating pregnancy by resorption rather than by abortion
    • effective as early as 25 days after the 1st mating
  • All the treated bitches returned in heat and become pregnant and had normal litters. Thus, this treatment did not compromise the fertility of the treated animals.







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