CANINE REPRODUCTION REPRODUCTION - Zoovet cycles per year the cycles are identic even if pregnancy...

CANINE REPRODUCTION CANINE REPRODUCTION REPRODUCTION REPRODUCTION

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BACK TO SCHOOL

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Action of the hormones on uterus

The sexual cycle of the bitch

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- Stages of the sexual cycle

- Main hormones

- Action of the hormones on uterus

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THE SEXUAL CYCLE OF THE BITCH

2 cycles per yearthe cycles are identic even if pregnancy or not

4 stages rhythm by the sexual hormonesproœstrusœstrusmétœstrus = postoestrusanœstrus

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STAGES OF THE SEXUAL CYCLE

Heat

Sexual inactivityPregnancy or not

ovary

folliculeovule

Estrogens ’ secretion

Prooestrus

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THE SEXUAL CYCLE : OVARIAN LEVEL

ovulation

Estrogens ’ secretion

Transformation of follicule intocorpus luteum

Secretion of progestérone

Proœstrus Oestrus

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corpus luteum

Secretion of progestérone

Proœstrus Oestrus Metœstrus

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Disappearanceof the corpus

luteum

Progressive degeneration[pseudopregnancy]

Rapide lysis through Prostag. [parturition]

Proœstrus Oestrus Metœstrus Anœstrus

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Proœstrus Oestrus Metœstrus Anœstrus

Sexualinactivity

15-20 days 2 months 3,5 months

HeatPregnancy

or Pseudopregnancy

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Action of the hormones on uterus

The sexual cycle of the bitch

2

10

PROOESTRUS

Progesterone ng/ml

oestradiol pg/ml

OESTRUS ANOESTRUSMETOESTRUS

D 63

Brutal drop beforeparturition

Fertilization Implantation : D 22

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MAIN SEXUAL HORMONES

Precocious abortion Late abortion

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PROOESTRUS

10

Progesterone ng/ml

oestradiol pg/ml

ANOESTRUS

Progressive drop if absence of pregnancy

OESTRUS METOESTRUS

D 63

10

Progesterone ng/ml

oestradiolpg/ml

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The hormonal profile is identical if the bitch is pregnant or not

Beginning of proœstrus

Thin uterine mucosa, without folds

Opening of cervix

Estrogens

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ACTION OF THE HORMONES ON UTERUS

Preparation of the uterine mucosa

Open cervixUpflow of germs

Estrogens

Synthesis of progesterone

receptors

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Oestrus


Ovulation

: Progesterone receptor

Upflow of germs

Blood flow + severalleukocytes

prevent the bacterialcontaminations

Estrogens

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Oestrus


. Uterine milk

Closed cervix

. Important development of the uterinemucosa

progesterone

Development of the egg if Fertilization

: Progesterone receptors

Control of musculature

Regulation of defenses

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Metoestrus


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Progesterone


•Prepare the uterine matrix

•Close the cervix

•Inhibit the contractions of uterine musculature

•Regulate the immunitary defenses

It creates propitious conditions for the physiological life or pathological development in

the uterine lumen

Placenta

Closed cervix

Foetalampulla

progesterone

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Metoestrus with pregnancy


Amniotic liquid

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Metoestrus with pregnancy


Ultrasonography

Uterine lumen

Fœtal ampulla

. Closed cervix

progesterone

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Metoestrus without pregnancy


. Uterine milk

. Very developed uterine mucosa

Propitious conditions for bacterialmultiplication

Opened cervix

Suppression of

progesterone

Involution of uterus

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End of Metoestrus or parturition


Restart of uterine

contractions

Inactive uterus,

thin uterine mucosa without

foldsThe cervix is

not always completly hermetic

Mucous plug

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Anoestrus : sexual inactivity


MEDICAL METHODS TO TERMINATE CANINE PREGNANCY

/ Estrogens/ Prostaglandins/ Inhibitors of progesterone synthesis (Epostane)/ Ergoline derivatives (Bromocriptine, Cabergoline)/ LHRH antogonists (Detirelix and RS15378)/ Antimitotic agents/ Tamoxifen/ Corticosteroids treatments


/ ESTROGENSmainly estradiol benzoatemode of action (hypothesis):

modification of the mobility of uterotubal junction and expulsion of premature ova or delayed transport of the ova in the oviduct (=>degeneration)modification of the biochemical environment of oviduct and uterus (induction of histological change of implantation site)

side effects:extended estrushigh risk of cyctic endometrial hyperplasia and pyometra


/ PROSTAGLANDINSadministration during 2nd half of the luteal phasemode of action:

gradual and complete luteolysis (=> lowering of plasma progesterone concentration)possible uterine contractions (PGF2 alpha) and dilatation of cervix

disadvantages and side effects:Off label useineffective on early pregnancy (days 5 to 17)salivation, vomiting, diarrhoea, hyperpnea and ataxia (limited by use of atropine => antagonises also uterine contractility)


/ INHIBITORS OF PROGESTERONE SYNTHESIS (EPOSTANE):

mode of action:decrease of progesterone synthesis from pregnenolone through inhibition of an enzyme of steroidogenesis (3-beta-hydroxy-steroid-dehydrogenase) termination of pregnancy if administration during metoestrus

disadvantages and side effects:Off label usedevelopment of large abscesses if administration by subcutaneousroute

/ ERGOLINE DERIVATIVES (BROMOCRIPTINE, CABERGOLINE):

mode of action:inhibition of prolactin secretion (direct stimulation of dopamine receptors on pituitary cells)lost of luteotrophic support of the corpus luteum and decrease of plasma progesterone concentration (administration from the second half of luteal phase = day 42) => abortion

disadvantages and side effects:Off label uselong administration: 4 days (bromocriptine) to 5 days (cabergoline)action on CNS: vomiting, nausea, anorexia and polydipsia (less severe action for cabergoline)



/ LHRH ANTAGONISTS (DETIRELIX, RS15378):mode of action:

action in very early stages of developmentstimulation of synthesis and release of gonadotrophic hormones => modification of synthesis of steroids hormones in gonadssuppression of luteal function from day 20 of pregnancy => resorptionand abortion

disadvantages and side effects:Off label usehigh doses are requiredmast cells degranulation (release of histamine and inflammatory mediators)less severe with RS15378


/ ANTIMITOTIC AGENTS:phenyl-triazole iso-indole (Privaprol), isoquinoleinesmode of action:

degeneration of the conceptus (absorbed and expelled)acts after implantation of the ova in the uterus

side effects:pyometra in treated dogs

/ TAMOXIFEN (Off label use):pure antiestrogen (with no agonistic effect): higher affinity for estrogen receptors than estradiol


/ CORTICOSTEROIDS TREATMENTS:mode of action:

the exact mode of action is not known

disadvantages and side effects:Off label useadministration in 2nd half of pregnancylong treatmentcorticoids side effects: polyphagia, polydipsia and polyuria


PRODUCTS PERIOD OF EFFICACY DISADVANTAGES

Estrogens Efficient before implantation of the ova intouetrus

Estrus extension Bone marrow hypoplasia Cystic endometrial hyperplasia Pyometra Repeated administration

Prostaglandins Efficient on the 2nd half of the luteal phase Salivation, vomiting, diarrhoea,respiratory distress

Repeated administrationsErgoline derivatives Efficient on the 2nd half of the luteal phase Inefficient on the 1st half ofpregnancy

Action on CNS : nausea, apathy,anorexia, polydipsia

Repeated oral administrationInhibitors of progesterone synthesis Efficient before ova implantation in uterus Large abcesses (SC route)

Repeated injections

LHRH antagonists Efficient from day 20 of pregnancy High dosages required Mast cells degranulation (histamine,

inflammatory mediators)Antimitotic agents No hormonal activity

10 – 12 days after mating Severe side effects (pyometra)

Tamoxifen Efficient early in the pregnancy Repeated administrations by oral route

Corticosteroids Long treatment Polyphagia, polydipsia and polyuria

Excepted estrogens and some antimitotic agents like Privaprol: OFF LABEL USE

CANINE REPRODUCTION REPRODUCTION - Zoovet cycles per year the cycles are identic even if pregnancy...

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Transcript of CANINE REPRODUCTION REPRODUCTION - Zoovet cycles per year the cycles are identic even if pregnancy...