Principles of Exogenous Hormone Use Flashcards
How can we control follicular and luteal function directly
Stimulate follicular growth (FSH)
Stimulate ovulation (hCG/LH)
Luteolysis (PGF2A)
How can we control follicular (and luteal) function indirectly
GnRH: LH effect likely to dominate
How can we control the hypothalamus
Suppress with P4
Longer duration needed
What is needed for PGF2A to act
Active CL
What is needed for GnRH/LH to trigger ovulation
Dominant (large) follicle
What is needed for FSH to recruit multiple dominant follicles
Growing antral follicles
What is the effect of giving reproductive sex steroids to males
Negative feedback on hypothalamus and pituitary
Reduction of reproductive function
Androgens, oestrogens, progestogens (have same effect as in female-> -ve feedback on hypothalamus)
When might you give progestogen to a male dog
For a peri-anal tumour, the growth of which is stimulated by normal testosterone concentrations
Giving a depot progestogen (proligestone, ‘Delvosteron’), decreases testosterone and supresses spermatogenesis
Why would you use a progestogen instead of oestrogens in male dog to treat a peri-anal adenoma
Oestrogens cause bone marrow suppression (and anaemia and thrombocytopaenia)
When would you use a GnRH agonist in a male dog
A dog with an overly high libido
It causes initial stimulation but then receptor down regulation -> reduces GnRh effects
Can gonadotropins be given to male dogs to improve fertility
no
they have limited impact because we cannot mimic the way in which they are released naturally (where the amplitude and pulse frequency of concentration is important for the biological effect
So giving GnRH or FSH or LH does not improve semen quality
When would you give hCG (LH-like in activity) to a male dog
to confirm the presence of testicular tissue
e.g. Rig test
Common drugs given to male dogs to control reproductive function
Progestogens
Depot GnRH preparations
GnRH for testing for presence of a testis
hCG (LH-like) for testing for presence of a testis
