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SMALL ANIMAL > 16.8.3: Principles of contraception > Flashcards

16.8.3: Principles of contraception Flashcards

1
Q

Which drugs can act at point 2 in this diagram?

Diagram = female

A

GnRH agonists

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2
Q

Effect of GnRH agonists

A

Depends on the time frame
Short term
* e.g. buserelin injection, deslorelin implant
* Causes stimulation of LH and FSH release

Long term
* Deslorelin (suprelorin) implant
* Causes initial stimulation and then receptor down-regulation (there is a block at the level of the pituitary, so there is then no stimulation of the ovary and testes)

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3
Q

What might we use long-acting GnRH implants (e.g. deslorelin; Brand name= Suprelorin) for?

A
  • Control and fertility in male dogs
  • Temporary suppression of oestrus in bitches
  • Delaying puberty in bitches
  • Treatment of anal adenomas (testosterone stimulates this)

GnRH agonist can be used to inhibit reproduction in males and females of aff species (dose-dependent).

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4
Q

What can deslorelin be used for?

A

Deslorelin = GnRH agonist
* Short-term: can be used to induce ovulation
* Long-term: can be used to inhibit reproduction/control behaviour
* Ferrets: can be used in the management of adrenal disease

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5
Q

Effects of progestogens

A
  • Progestogens exert a powerful negative feedback effect upon the hypothalamus/pituitary
  • Central sedative effects
  • Closes cervix
  • Stimulates endometrial proliferation
  • Suppresses myometrial activity
  • Mammary enlargment

Examples: proligestone, osaterone

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6
Q

Proligestone is a:
a) prolactin inhibitor
b) GnRH agonist
c) progestogen
d) prostaglandin

A

c) progestogen

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7
Q

Adverse effects of progestogens

A
  • Increased appetite/weight gain
  • Mammary enlargement ± benign nodules/neoplasia
  • Risk of cystic endometrial hyperplasia
  • Diabetogenic (insulin antagonism)
  • Acromegaly
  • Coat changes esp local reactions following SC injections
  • Masculinised female pups and cryptorchic pups if given in pregnancy
  • Suppression of spermatogenesis

Adverse effects are less in newer generation compounds. We are moving away from using progestogen now we have GnRH agonists like deslorelin.

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8
Q

How can we use progestogens to control oestrus?

A

If progestogens are given in anoestrus, the occurence of oestrus is prevented through negative feedback

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9
Q

How can we use progestogens for pseudopregnancy?

A
  • Progestogens given as depot therapy e.g. proligestone, delmandinone
  • Normally, a fall in progesterone stimulates a rise in prolactin which causes the pseudopregnancy
  • When progestogens are given, they inhibit the release of prolactin from the pituitary gland, thereby preventing pseudopregnancy
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10
Q

What can we use progestogens for in males?

A
  • Anything relates to high concentration of testosterone e.g, antisocial behaviour, prostate disease, anal adenoma
  • Progestogens will result in reduction of FSH and LH secretion
  • Lower LH -> Leydig cells affected -> lower androgens
  • Lower FSH -> Sertoli cells affected -> reduced spermatogenesis
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11
Q

What are the possible adverse effects of oestrogens?

A
  • Potentiate the effects of progesterone on the uterus -> pyometra
  • Dose-related bone marrow suppression -> anaemia, thrombocytopaenia -> death
  • Stimulate signs of oestrus
  • Non-pruritic bilaterally symmetrical alopecia and hyperpigmentation
  • If given during pregnancy, may cause abortion
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12
Q

Examples of oestrogens used in practice

A
  • Oestradiol benzoate
  • Estriol (Brand name= Incurin)
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13
Q

What can we use oestrogens for in practice?

A
  • Oestrogens have a negative feedback effect but are predominantly used for their target tissue effects
  • They cause oedema of the repro tract, pheromone producton, changes in function of the uterine tube and uterus (support sperm transport and the environment for fertilisation)
  • Used for management of unwanted mating or incontinence
  • Use carefully, at low doses or topically
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14
Q

How can oestrogens be used for unwanted mating?

A
  • Licensed: oestradiol benzoate. Not currently on sale but still in some practices.
  • This prevents implantation and/or interferes with the transport of zygotes
  • Animals may continue to show signs of oestrus; if re-mated, unlikely to become pregnant
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15
Q

How can oestrogens be used to treat urinary incontinence?

A
  • Oestrogens (e,g. estriol, brand name= Incurin) have a direct effect on the reproductive tract
  • This increases urethral mucosal thickness
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16
Q

What effect do androgens have on males and what could they be used for?

A
  • Androgens mimic the action of testosterone and so have a negative feedback effect
  • This leads to less LH and FSH production -> less testosterone production and reduced spermatogenesis)
  • This has an effect on target tissues (testicular atrophy) -> induce temporary infertility in males
  • e.g. Durateston
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17
Q

What are the clinical uses of eCG in dogs?

A

There are none.
You’d imagine that it would mimic FSH and stimulate oestrus, but it doesn’t do this in practice.

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18
Q

What are the clinical uses of hCG in dogs?

A
  • hCG = LH-like in activity
  • Can use hCG to force a follicle, or follicular cyst, to ovulate if the animal is in oestrus; i.e. to hasten or force ovulation
  • Can use hCG to stimulate a gonad if you are trying to work out if it is present. e.g. if ovary present -> oestrogen will rise; if testis present -> testosterone will rise)
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19
Q

Adverse effects of prostagladins

A
  • Restlessness
  • Hypersalivation
  • Vomiting
  • Abdominal pain
  • Diarrhoea
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20
Q

True/false: we can use prostaglandins to induce oestrus in the dog.

A

False
* We can use prostaglandins to induce oestrus in the polyoestrus animal.
* The dog is monoestrus - if we try to use prostaglandin to unduce oestrus, we will just end up pushing her into anoestrus.

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21
Q

What effect do prostaglandins have on the CL in the bitch and queen? From when do they have this effect?

A
  • Prostaglandins cause lysis of the CL but the early CL will usually not respond
  • In the bitch and queen, the CL is autonomous for the first 15 days of the luteal phase
  • Practically, prostaglandins are of little use before Day 20
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22
Q

How would you use prostaglandins to terminate a pregnancy?

A
  • Use low doses 2x daily for 5-10 days
  • Commence after day 20
  • Termination occurs by resorption or abortion

The above protocol is for prostaglandins alone - we can use prostaglandins with prolactin inhibitors.

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23
Q

Which would you use to treat post-partum metritis in the bitch and why?
a) prolactin inhibitor
b) prostaglandin

A

b) prostaglandin
* Prolactin inhibitors would not be effective here because they knock out progesterone, but a post-partum bitch has no progesterone.
* Prostaglandins are useful for their spasmogenic effects, promoting involution of the uterus.

24
Q

When should you not use prostaglandins around or/after birth?

A
  • Don’t administer if the cervix is closed
  • Don’t administer in cases of obstructive dystocia
25
Q

Which drug could be used to do the following?
* Stimulate uterin contraction to facilitate parturition (when there is a fully dilated cervix)
* Promote involution of the post-parturient uterus and thus aid the passage of the retained placenta
* Aid in the control of the post-partum haemorrhage
* Promotion of milk let-down in cases of agalactia

A

Prostaglandin

26
Q

Prolactin agonists are ———— antagonists

A

Prolactin agonists are dopamine antagonists

27
Q

What is the principal luteotrophic agent in the bitch and queen?

A

Prolactin

28
Q

What effect does removal of prolactin have on ovarian structures?

A
  • Removal of prolactin causes demise of the CLs
  • Progesterone rapidly declines
  • This terminates the luteal phase
  • There are fewer adverse effects than prostaglandins, with no effect on the uterus
29
Q

Cabergoline is:
a) a prostaglandin
b) an androgen
c) a prolactin inhibitor
d) an oestrogen

A

c) a prolactin inhibitor
Cabergoline brand name= Galastop

30
Q

Adverse effects of prolactin inhibitor

A
  • Nausea and vomiting
  • Lethargy
  • (Abortion)
  • (Return to oestrus)
31
Q

True/false: we can use prolactin inhibitors to treat pseudopregnancy

A

True

32
Q

What could we combine with a prolactin inhibitor to treat pyometra? Why would we do this?

A

Prolactin inhibitor + Prostaglandin
e.g. Cabergoline + Cloprostenol

  • Give the prolactin inhibitor 1-2 days before giving the prostaglandin
  • This lyses the CL and lower progesterone, softening the cervix ready for prostaglandin
33
Q

True/false: if you give prostaglandin to a dog with a closed cervix, there is a risk of uterine rupture.

A

True

34
Q

Aglepristone is:
a) a prolactin inhibitor
b) a progestogen
c) a progesterone receptor antagonist
d) a prostaglandin

A

c) a progesterone receptor antagonist
Aglepristone brand name= Alizin.

35
Q

What will happen to blood progesterone levels when you give a progesterone receptor antagonist?

A
  • Progesterone receptor antagonist = synthetic steroid which pushes progesterone off the receptor but produces no signal
  • Blood progesterone concentration remains normal, but the progesterone isn’t having an effect
36
Q

Potential uses of progesterone receptor antagonist

A
  • Prevention of implantation
  • Termination of pregnancy at any stage
  • Possible treatment of pyometra but may not lead to expulsion
37
Q

What could you use to terminate pregnancy at any stage in the bitch?

A

Progesterone receptor antagonist e.g. Aglepristone

38
Q

How could you use aglepristone to treat an unwanted mating?

A
  • Can treat unwanted mating up to 20 days after mating
  • Give 2 doses 24hrs apart
  • May see local injection site reaction
39
Q

What is the effect of melatonin in short-day breeders?

A

More melatonin -> upregulation of short day breeders e.g. sheep

40
Q

What is the effect of melatonin in long-day breeders?

A

More melatonin -> downregulation of long day breeders e.g. cats

41
Q

What could you use melatonin for in the cat?

A
  • Not licensed
  • Can be used to suppress oestrus in cats
42
Q

Advantages of surgical sterilisation in the bitch

A
  • Reduction in incidence of mammary neoplasia especially if neutered before puberty
  • Prevention of uterine disease including CEH, pyometra and uterine neoplasia
  • Prevention of ovarian disease including neoplasia
  • Prevention of endocrine disease e.g. pseudopregnancy
43
Q

Disadvantages of surgical sterilisation in the bitch

A
  • Changes in coat texture
  • Changes in behaviour
  • Tendency to gain weight
  • Increased incidence of some neoplasia in some breeds
44
Q

Benefits of ovariectomy compared to ovariohysterectomy

A

✅ Simpler
✅ Less traumatic
✅ Faster
✅ More rapid recovery
✅ Cheaper
✅ Fewer surgical risks
✅ More amenable to laproscopic surgery

45
Q

You perform an ovariectomy on a dog. Under what circumstances might she suffer uterine disease?

A
  • If her uterus was already abnormal
  • If you left in an ovarian remnant
  • If there is a neoplasm producing reproductive steroids e.g. adrenal neoplasm - rare
  • If exogenous reproductive steroids are administered e.g. progestogens for skin disease, oestrogens for urinary incontinence
46
Q

When should you spay a bitch and why?

A
  • Either 3-4 weeks post-oestrus, before there will be a rise in prolactin and iatrogenic pseudopregnancy
    OR
  • Greater than 12 weeks after oestrus as the bitch will now be in anoestrus
47
Q

Advantages of castration

A

✅ Elimination of testicular disease
✅ Elimination of most prostatic disease
✅ Behaviour modification (not guaranteed; some behaviour is learned and libido may be retained for years if castrated after puberty)

48
Q

Disadvantages of castration

A

❌ Increased risk of some neoplasia
❌ Behaviour - some dogs becoming more nervous-aggressive with loss of testosterone

49
Q

How soon after castration will a dog become infertile and what does this depend on? How does this differ in the stallion?

A
  • Onset of infertile ejaculate depends on the degree of sperm storage in the ampulla
  • Dogs have a very small ampulla -> therefore azoospermic in a few days
  • Stallions have a very significant ampulla -> therefore sperm may be detected for several weeks/until he ejaculates
50
Q

Which of the following describes how you would expect a case with an ovarian remnant/incomplete ovariectomy to present?
a) Oestrus behaviour occurs at the normal interval with normal cyclicity
b) Oestrus behaviour is absent for months-years and is then normal/weak/persistent ± normal cyclicity
c) Oestrus bheaviour is absent for many years until persistent weak behaviour associated with a granulosa cell tumour is detected.

A

All of the above

51
Q

What methods could we use to diagnose incomplete ovariectomy (ovarian remnant)?

A
  • Can diagnose based on clinical signs/behaviour
  • Vaginal cytology and vaginoscopy - can detect prooestrus and oestrus
  • Ultrasound of oavries - if animal not obese
  • Stimulate the ovary to produce oestrogen by giving GnRH of hCG - works best when the dog is in anoestrus
  • Measurement of anti-Mullerian hormone (has false +ves and -ves)
    Plan of action: establish when last alleged oestrus was observed. Consider where it would be in its cycle now and what diagnostics you can do.
52
Q

If a dog showed its last oestrus 2 months ago or less, it is in the…

A

luteal phase

53
Q

If a dog showed its last oestrus over 2 months ago, she is in…

A

anoestrus

54
Q

How could you detect an ovarian remnant in the queen?

A
  • She will generally cycle every 2-3 weeks
  • Examine when in oestrus: clinical exam, behaviour, vaginal cytology, ultrasound of ovary
  • Could give this cat hCG to make it ovulate, then see back a week later. If there is an ovary present, the cat’s progesterone concentration will rise after ovulation because it enters the luteal phase.
55
Q
A
  • Could give a deslorelin implant -> this will provide stimulation of the gonads (or would, if he wasn’t neutered) leading to high FSH but eventually negative feedback. There may be LH receptors in this tumour which would response to this.
  • Could give reproductive sex steroids e.g. progestogens for their negative feedback effect. Progesterone will also have a direct effect on the prostate.
56
Q
A
  • Could do nothing and hope
  • Could try using hCG (which has LH-like activity)
  • Could give a short-acting GnRH agonist
  • These drugs would both stimlate ovulation

SMALL ANIMAL (90 decks)

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