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Module 22: Reproduction & Fertility > Hormones in SA Fertility Control > Flashcards

Hormones in SA Fertility Control Flashcards

1
Q

what are the hormonal options and pathway/specific actions for contraception

A

Progestagens (=progesterone and synthetic progestogens aka progestins)

  • Suppress GnRH/LH pulses and the GnRH/LH surge in the female, thus follicle maturation, (proestrus) and ovulations
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2
Q

what are the progestagens used for canine contraception

A
  1. Medroxyprogesterone acetate (MPA): (Promone-E)
  2. Megestrol acetate (MA): (Ovarid)
  3. Proligestone: (Delvosteron)
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3
Q

how is proligestone (delvosterone) used long term

A

postponement of heat

Repeat injections given in anestrous induced by the previous injection

At 3, 4, 5 months then every 5 months

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4
Q

how is proligestone (delvosterone) used short term

A

A single injection given in anestrus

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5
Q

how is proligestone (Delvosterone) used to suppress heat after onset

A

Single injection given at the beginning of pro-estrus

Wait 5 days to 1 week until contact with entire male

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6
Q

how do the side effects of proligestone (delvosterone) compare to MA and MPA

A

less side effects

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7
Q

how is estrus suppression done in the queen

A

Very high fertility rate —> need to manage reproduction

Long or short term and reversible suppression possible with Progestins such as MPA, MA, proligestone

Use at lowest possible doses to reduce side effects

Other progestins available but less evaluated

Essential to advise owners of risks/benefits

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8
Q

how is megesterol acetate (MA) used in bitches

A

Oral, dogs/cats

Use at beginning of proestrus or anestrus

  • Avoid during metestrus and diestrus (luteal phase)

Suppress estrus

Short acting compound in tablet form, daily administration

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9
Q

how is medroxyprogesterone acetate (MPA) used in bitches

A

Subcutaneous depot injection

Treat only anestrous bitches

  • If not in anestrous will overdose with progesterone —> side effects
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10
Q

what are adverse side effects of progestogens

A

Cystic endometrial hyperplasia

Pyometra

Mammary hypertrophy and possibly mammary tumours

Weight gain

Diabetes mellitus

Adrenal suppression

  • Megestrol acetate is used in cats for its corticoid activity in military eczema)

Coat and behavioural changes

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11
Q

when are progesterones contraindicated

A

diabetes mellitus

liver disease

mammary tumours

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12
Q

why would you want suppress fertility in male dogs

A

Puberty dependent on breed (size)

If sexual behaviour of the dog is not compatible with the environment but want to breed from him later

Several hormonal options available

Hormonal treatment is reversible and can be short or long term

  • Reversibility is a bit more unpredictable after long term

Essential to advise owners of time to infertility following treatment, risks/benefits

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13
Q

what are the hormonal options and pathways/specific actions to suppress fertility in male dogs

A

All reduce testosterone (T) or actions of testosterone

  • Progesterone negative feedback (synthetic progestogens)
  • GnRH agonist-induced down regulation of LH and T
  • Androgen receptor antagonist action
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14
Q

what are the options to suppress fertility using progesterone in male dogs

A

Delmadinone acetate SC or IM for dogs/cats (Tardak)

Megestrol acetate (Ovarid)

Osaterone tablets (Ypozane)

Rapid effects of T

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15
Q

what are the GnRH options to suppress fertility in male dogs

A

GnRH agonist incuded down regulation of LH and T

Deslorelin implant (Suprelorin)

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16
Q

how does Deslorelin implant (Suprelorin) work in male dogs

A

GnRH agonist (144x activity)

Occupies GnRH receptor constantly

Down regulates LH release

Reduces Leydig cell testosterone production

Long half life and high potency

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17
Q

how long does testosterone suppression take when using a deslorelin implant

A

Suppression of testosterone production takes 6-8 weeks

Reduced sperm production and motility

Infertility from 8 weeks-6 months (4.7mg) or 12 months (9.4mg) after insertion

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18
Q

what are the side effects of deslorelin implant

A

none

reversible but recovery can be unpredictable

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19
Q

what are the androgen receptor antagonist options to suppress fertility in male dogs

A

Osaterone tablets (Ypozane)

Flutamide

20
Q

how is fertility suppressed in tom cats

A

Usually permanent suppression (surgery)

If sexual behaviour of tom cat not compatible with environment but want to breed later?

Do not use progestins due to higher risk of diabetes and mammary gland hypertrophy

1x Deslorelin 4.7mg implant:

  • Infertility from 3-12 weeks
  • Infertility from 6-24 months
  • But not licensed

Essential to advise owners of time to infertility following treatment, risks/benefits

21
Q
A
22
Q

how is MA used in the queen

A

Oral administration

Short acting, weekly doses sufficient

Suppression of heat (calling) even if already started

Corticoid activity and adrenal suppression possible

23
Q

how is MPA used in the queen

A

Check availability

Very long half life if IM administration

  • 6 weeks to 2 months

Fertility subsequent first cycles reduced

Side effects seen on mammary glands

24
Q

how is proligesterone used in the queen for permanent postponement of calling

A

Repeat injections given in anestrus induced by the previous injection

At 3, 4, 5 months then every 5 months

25
Q

how is proligestone used to temporarily postpone calling in queens

A

A single injection given in inter-estrus or anestrus (not in diestrus)

26
Q

how is proligestone used to suppress calling after onset in queens

A

Single injection given at the beginning of estrus

Wait 5 days - 1 week until contact with entire male

27
Q

what is pseudopregnancy

A

A physiological state

Adapted to ensure pups in wild could nurse from other (subordinate) females (cooperative breeding)

Occurs as part of many canine estrous cycles

Variable degree of ‘problem’ behaviour or mammary gland enlargement and lactation

28
Q

what are the hormones of pseudopregnancy

A

Non-pregnant bitches have a very long luteal phase which supports mammary gland development just like in pregnancy

The decline in progesterone with increase of prolactin, particularly at end of pregnancy lead to mammary gland development and onset of lactation

If bitches are showing signs, this is possibly due to:

  • Differences in prolactin concentrations
  • Differences in sensitivity to prolactin
29
Q

if OVH is done in which estrous stage, can lead to pseudopregnancy

A

in luteal phase

30
Q

when does pseudopregnancy occur

A

6-8 weeks after estrus

31
Q

what are the signs of pseudopregnancy

A

Signs very similar to late preg:

Weight gain

Vomiting

Mammary gland enlargement

Onset of lactation

Licking

PU/PD

Behaviour change (nesting, mothering inanimate objects, aggression)

32
Q

how is pseudopreg differentiated

A

US scan/x ray if not sure

relaxin ELISA

33
Q

how is pseudopreg treated

A

Consider whether conservative treatment (exercise) is sufficient or mild or non-serious signs

Some evidence for increase in mammary neoplasia after several pseudopregnancies

Hormonal treatment if lactation or more severe behavioural changes

34
Q

how is pseudopreg treated using hormones

A

anti-prolactin agents (dopamine agonists) such as bromocriptine and cabergoline

35
Q

what is the action of dopamine agonists and how are they used to treat pseudopreg

A

Suppress lactation and cause luteolysis (thus terminate pregnancy)

36
Q

what is bromocriptine

A

dopamine agonist

Bromocriptine

Side effects are vomiting, anorexia and depression

Not licensed for animals

37
Q

how is cabergoline used

A

Oral administration

Expensive

Effective and safe in both entire and spayed bitches

Once daily dose for 6d or 13d if symptoms persist

Will cause faster luteolysis

  • Next proestrus is advanced if cyclic
  • If pregnant can cause abortion
38
Q

how is metergoline used

A

anti-serotonin action so enhances endogenous dopamine

39
Q

how can misalliance/unwanted pregnancies be managed

A

“Alizin” aglepristone (injection)

Ovariohysterectomy

Cabergoline (oral) usually combined with prostaglandins (cloprostenol)

40
Q

what is the mechanism of aglepristone (‘alizin’)

A

Synthetic steroid

Progesterone receptor antagonist

  • Competes with progesterone at nuclear receptors
41
Q

when can aglepristone be used

A

until 45d

42
Q

how is aglepristone used

A

2 injections SC 24 hours apart (or within 24 hours)

43
Q

what are the side effects of aglepristone

A

few adverse effects

stings/local tissue irritation

44
Q

what is mesalin (estradiol benzoate) and what are the adverse effects

A

May still be available in some countries and practices

2 injections on days 3 and 5 post mating —> bitch back in estrus

A further injection on day 7 if mated more than once

Inexpensive

95% success rate

Risk of adverse affects are high:

  • Pyometra
  • Bone marrow suppression
  • Damage to pups if unsuccessful
  • Can still breed subsequently if no adverse affects
45
Q

what are the pros of OVH to terminate unwanted pregnancy

A

No risk of recurrence

No risk of pyometra etc

46
Q

what are the cons of OVH for unwanted pregnancy

A

Surgical challenge

Lactation

  • Mammary gland development as OVH in luteal phase
  • Pseudopregnancy

Ethics?

Cost?

47
Q

how can unwanted pregnancy be managed in cats

A

Up to 45 days can use Aglepristone

OVH is usual choice in practice

  • Midline if pregnant to gain better access

Module 22: Reproduction & Fertility (27 decks)

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