Non-surgical Control of Reproduction Flashcards
where is GnRH produced?
hypothalamus
Pulsatile secretion of ______ causes gonadotropin secretion (FSH, LH)
GnRH
What hormone is dominant in the follicular phase to allow for follicular growth?
FSH
Which hormone is key for dominant follicles and surges just prior to ovulation in dogs/cats?
LH
__________ has negative feedback on the hypothalamus and pituitary and increases as a result of growing follicles.
estradiol
If estradiol has negative feedback on the hypothalamus and the pituitary, what hormones does this down-regulate?
GnRH, FSH, LH.
Which hormone is dominant during the luteal phase?
progesterone
which hormone is luteotrophic and involved with lactation?
prolactin
Estradiol is the hormone produced by the ovaries. When does estradiol peak in the canine cycle?
Estradiol is produced by the ovaries during proestrus and PEAKS ~1-2 days before estrus.
proestrus lasts ~6-11 days
What hormone elevation marks the start of estrus in the dog?
LH
This is caused by decreased estrogen and increasing progesterone.
When does progesterone peak in reference to ovulation?
2-3 weeks AFTER ovulation.
T/F: anestrus is the stage of the canine cycle that occurs either at the end of the heat cycle or after having a litter of puppies
true
progesterone remains low
uterus undergoes involution
Estrus control is NOT considered a good non-surgical population control option for which of the following scenarios?
A. when needing irreversible results
B. breeding animals
C. high-risk surgical or anesthetic candidates
D. risks involved with pursuing surgery
A. when needing irreversible results
this is a reversible type of non-surgical control.
Which of the following is FALSE about Megestrol Acetate (MGA)?
A. MGA is a progestin
B. MGA has temporary effects
C. MGA comes in oral or injectable forms
D. MGA blocks the production and release of GnRH
E. MGA upregulates LH surge
E. MGA upregulates LH surge
inhibits the LH surge as a result of blocking the production/relase of GnRH
What is the MAIN use of Megestrol Acetate (MGA)?
suppress or prevent cycling for 4-6 months.
State for each stage of the canine cycle when you should administer Megestrol Acetate (MGA) if you are desiring to suppress cycling for 4-6 months?
In anestrus:
In proestrus:
In anestrus: 1 week prior to expected proestrus
In proestrus: within the first 3 days of proestrus
T/F: when giving MGA during proestrus, the bitch will still be attractive to males until her clinical signs resolve
true
Which of the following is NOT a contraindication for the use of progestins?
A. prior to pubertal heat
B. use for 2+ consecutive cycles
C. if repro tissue disease is present
D. if animal needs to have the ability to get pregnant in the future
E. if older bitch
F. if bitch has liver disease
D. if animal needs to have the ability to get pregnant in the future
you should NOT give these drugs prior to pubertal heat because they can force puberty before the bitch is ready. Using progestins for more than 2+ consecutive cycles increases pyometra risks and other uterine pathology.
Name 6 risks associated with progestin use
- uterine pathology
- mammary tumors
- metabolic and growth hormone??
- acromegaly
- adrenal suppression
- break through estrus signs
T/F: there is a high risk for pyometra when using progestins, despite the dose.
false – low risk when used at recommended dose in anestrus
What drug are the following effects associated with?
- endometrial proliferation
- myometrium hypertrophy
- cervical closure
- dormancy of uterus
- increased growth hormone secretion
- appetite and behavior
progesterone and progestins
What drug is a synthetic weak androgen?
mibolerone
__________ is a drug whose mechanism is to suppress the HPO axis and has a direct effect on estrogen receptors or tissue due to sensitivity.
mibolerone (a synthetic androgen)
when should you administer mibolerone?
when the bitch is in the FIRST half of anestrus
Which of the following are contraindications for the use of mibolerone?
A. use for longer than 2 years
B. use in bedlington terries
C. after pubertal heat
D. normal reproductive tissue
E. liver or renal disease
F. A and B
G. A, B, C, and E
H. A, B, and E
H. A, B, and E
Name 5 side effects of mibolerone
clitoral hypertrophy
vulvar discharge
obesity
aggressive behavior
urinary incontinence.
Which of the following accurately describes the drug Deslorelin?
A. GnRH analog
B. synthetic androgen
C. synthetic progestin
D. dopamine agonist
E. synthetic prostaglandin
F. progesterone-receptor antagonist
A. GnRH analog
What is the mechanism for Deslorelin, a GnRH analog?
Causes an initial flare-up of GnRH which causes desensitization the pituitary gonadotrophs.
Continuous GnRH presence will downregulate the GnRH receptors.
T/F: deslorelin is a subcutaneous implant that causes irreversible suppression of fertility.
false – reversible.
It causes suppression of fertility for 2-27 months (variable) depending on the size of the implant.
For long-term estrus prevention, you can re-implant a 4.7 mg implant eery 4-4.5 months (off-label)
What are 3 side effects of deslorelin that are MORE common in older bitches?
- persistent heat
- CEH
- pyometra
What is the MOA of cabergoline in dogs?
in other species, is serves as a dopamine agonist and downregulates the HPO axis by inhibiting gonadotropin.
In bitches, we are unsure. It potentially could increase FSH or stimulate GnRH.
When should you give a dog cabergoline, a dopamine agonist?
every 24 hr in anestrus until 1-2 days into proestrus. Stop this medication after the LH surge to reduce the risk of an anovulatory cycle.
what are 2 side effects of cabergoline?
- vomiting
- coat color change
when should you implant deslorelin?
& when does the implant need to be removed?
implant ONLY in anestrus
remove prior to ovulation
What will result from a deslorelin implant?
proestrus will occur within 1 week. Ovulation will occur on average within 12 days post-implantation.
What are risks associated with the use of GnRH agonists?
- ovulation failure
- luteal insufficiency
- persistent heat
- ovarian cysts
- uterine disease
What is the MOA for aglepristone (Alizin)?
this drug is a progesterone-receptor blocker, which has a HIGHER binding affinity for progesterone receptor than natural progesterone and thus blocks progesterone’s effects.
What are 2 indications for the use of aglepristone?
- mismate
- pyometra
What is the MOA for dinoprost/cloprostenol?
causes luteolysis, smooth muscle contraction, uterine contraction and cervical opening.
What are 2 indications for the use of dinoprost/cloprostenol?
- mismate
- pyometra
________ is the main luteotropic homrone in the second half of pregnancy
Prolactin
Dopamine agonists such a cabergoline have what effect on prolactin?
dopamine agonists REDUCE prolactin
what is the major side effect of dopamine agonists such as cabergoline?
vomiting
Which of the following statements regarding feline cycles is FALSE?
A. cats are long-day breeders
B. cats are polyestrous
C. LH surge occurs pre-coitus
D. cats are induced ovulators
C. LH surge occurs pre-coitus
The LH surge occurs psot-coitus
What are 4 approved non-sx methods for estrus suppression in cats?
- deslorelin implants
- progestins (MGA)
- melatonin implants
- light therapy (<8hr light)
if you want to INDUCE estrus in cats you could:
- light therapy (12-4 hr)
- social stim (house with queens, pheromones from tom cats)
- hormonal
T/F: androgens such as mibolerone are NOT approved for use in cats
true
Which 2 hormones dose testosterone have negative feedback on?
FSH and LH
What does testosterone have positive feedback on?
GnRH
reproductive organs
What drug can be used to perform CHEMICAL castration in male dogs that causes temporary, reversible suppression of the testicular function?
GnRH agonists (suprelorin)
They cause an initial flare of testosterone.
What are 2 indications of chemical castration using GnRH agonists (suprelorin)?
- benign prostatic hyperplasia
- testosterone-related behavioral issues
how long would it take to completly restore fertility after chemical castration using a GnRH agonist (suprelorin)?
6-7 months
