contraception and termination of pregnancy

8/2/2019 Contraception and Termination of Pregnancy

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Contraception andTermination of Pregnancy

By Dr. Qaisar Shahzad


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Contraception?

Contraception is the prevention of the fusionof gametes during or after sexual activity.

The term contraception is a contraction ofcontra, which means against, and the wordconception, meaning fertilization.Contraception can occur both naturally and

via artificial means in humans and inanimals


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Contraception

Surgical Medical

Ovariohysterectomy Androgens

Progestogens

Immunization


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Surgical Methods for

Estrus SuppressionOvariohysterectomy and

Ovariectomy

Advantages:Permanent

Reduces mammary tumor

Disadvantages:

Produces less resting metabolic rate in cats

Obesity in dogs


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Tubal LigationAdvantages:

Can be performed laproscopically,

which requires less surgical time andpost operative care

Disadvantages:

It does not offer health advantages


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Pharmacological Methods for

Estrus Suppression

Progestogens

May act locally to prevent follicular growth

Estrogen production

OvulationDont alter LH levels


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Advantages of Progestogens:

Effective at suppressing estrus

Manufacturer of megesterol acetate reports noadverse effect on fertility when administered asdirected

Disadvantages:

Pyometra

Endometrial hypoplasia

Incidence of mammary carcinoma increases

In pregnancy causes fetal death,mummification ormaceration


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Progestogens Megesterol acetate (Ovaban; Schering-Plough)

Medroxyprogesterone acetate(Depo-Provera;Pharmacia & Upjohn)

Norethindrone (Primolut N;Schering-Plough)

Proligestone (Covinan; Intervet, Millsboro, Del.)

Levonorgestrel(50 j1g)/ethinylestradiol (30 j1g)(Nordette; Wyeth-Ayerst Philadelphia)


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AndrogensNegative feed to the pituitary gland decreases synthesis and

release of FSH and LH

Advantages:

Effective at suppressing estrus

1. Lack of estrogenic or progestational effects decreasesincidence of cystic endometrial hyperplasia/pyometra andmammary neoplasia as side effect

Disadvantages:

Mucoid vaginal discharges

Clitoral hypertrophy

Increased serum live enzymes


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Androgens

Mibolerone

Testosterone combinations (Durateston,Intervet)

Testosterone cypionate(Depo- Testosterone, Pharmacia & Upjohn)

Testosterone enanthate (Delatestryl; BTGPharmaceuticals, Iselin, NJ)

Boldenone undecanoate (Vebonol Novartis)

Methyltestosterone (Android; ICNPharmaceuticals,Costa Mesa, Calif.)


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GnRH Agonists

GnRH agonist bind to GnRH receptors on pituitary cells resultingin down regulation and decreases production of FSH and LH

Advantages:

Can suppress estrus upto 27mo in dogs and 14mo in cats

No long term effect on fertility has been reported

Disadvantages:

Initially there is induction of estrus

Minimal oedema at the site of injection


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GnRH antagonistGnRH antagonists bind to GnRH receptors on pituitary cellsand decrease the secretion of LH and FSH by preventinggene transcription

Advantages:

Reversible effect

Produces atrophy of organs and inhibits ovulation

Disadvantage:

Expensive drug

Localized skin erythema and pruritus may develop at thesite of injection site


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GONADOTROPIN-RELEASINGHORMONE AGONISTS

DesloreJin acetate(Peptech Animal Health, New South Wales)

GnRH ANTAGONISTS

Detirelix acetate


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Immunization against Zona

PellucidaAntibodies directed against zona Pellucida prevents bindingof spermatozoa and fertilization and impair oocytedevelopment and ovulation

Advantages:

Immunocontraception lasts for several months aftervaccination

It is reversible in some species

Disadvantages:

Ovarian atrophy

Polycystic ovarian disease

Autoimmune oophoritis


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Immunocontraception

Injection of a reproductive protein to produce ahumoral immune response that leads to fertility for a

defined period

Disadvantages: Skin irritation and localized pain at the

immunization site

Glomerulonephritis if antigen-antibody complex iscontinuously circulating


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Pregnancy Termination

Pregnancy termination is defines as expulsion of theproduct from uterus before the fetus is viable

It is also termed as induced abortion


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Estrogenic Compounds

Delay transport of embryo through uterine tube

Induces endometrial congestion and oedema therebypreventing normal embryo migration and implantation

Changes composition of uterine milk

Only safe if given after ovulation

Disadvantages:

Pyometra

Endometrial hyperplasia

Ineffective before ovulation


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ESTROGENIC COMPOUNDSDiethylstilboestrol

Estradiol cypionate (Depo-Estradiol,

Pharmacia & Upjohn)Estradiol benzoate

Tamoxifen citrate (Novadex; Astrazeneca,

Wilmington, Del.)


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Prosglandins

It induces vasoconstriction that reduces blood flow to corpusluteum with subsequent cellular degeneration. Prostaglandinalso induces myometrial contractility and contribute to cervicaldilation

Advantages: Few side effects

80-100% efficacy

Can be used as early as one week

Disadvantages: Duration of treatment averages 4 days

Tachypnea, hypersalivation, vomiting, ataxia, urination


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LUTEOLYTIC AGENTS(Prostaglandins)

Dinoprost tromethamine (Lutalyse,

Pharmacia & Upjohn) Cloprostenol (Estrumate, Schering-

Plough)

Fenprostalene (Bovilene, Fort Dodge)


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Dopamine agonist and Serotoninantagonist

Inhibition of prolactin secretion results in lutolysis

Advantages:

100% efficacy past the LH surge

Disadvantages:

Efficacy is 66% before 40 days


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DOPAMINEAGONISTS ANDSEROTONIN ANTAGONISTS Bromocriptine mesylate (Par/odel,

Novartis) Cabergoline(Dostinex, Pharmacia &

Upjohn

Metergoline


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Combination of Dopamine agonistand prostaglandin

Advantages

Its efficacy is 100% when initiated after 25days pastLH Surge


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Inhibitors of Progesterone Action

Progesterone receptors antagonists bind toprogesterone receptors with higher affinity than withendogenous progesterone

Advantages: Pregnancy is terminated within 4-7days of

instituting therapy

Disadvantages:

Mammary gland development occurs

It is less effective in feline pregnancy termination


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COMBINATIONSOFDOPAMINEAGONISTSANDPGF-2a Bromocriptine and cloprosteno

Cabergoline and cloprostenol

INHIBITORS OFPROGESTERONEACTION Mifepristone(RU486) (Mifeprex; Danco Laboratories, NewYork,

NY)

Aglepristone(RU534) (Alizine; Verbac Laboratories, Csttos,France)


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Dexamethasone

Corticosteroids mediate a luteolytic effect that is notwell understood

Advantages:

Very good efficacy after 30days past LH surge

Disadvantages:

Anorexia, polydipsia, polyuria


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Inhibitors of ProgesteroneSecretion

Epostame inhibits progesterone synthesis bycompetitive inhibition of enzymes involved in

the conversion of pregnanolone toprogesterone


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DEXAMETHASONE

NHIBITORS

OFPROGESTERONESECRETION Epostane (Hoescht-Roussel, KansasCity,

Mo.)


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contraception and termination of pregnancy

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