8- Principle of exogenous hormone use

Question 1

What effect does giving GnRH have in the short term

Answer 1

hasten ovulation by inducing LH surge
‘forces’ ovulation/ luteinisation of cystic structures

Question 2

What effects does giving GnRH long term have

Answer 2

Initial stimulation and then down-regulation GnRH receptor and thus suppresses HPG axis
Control behaviour & fertility in male dogs (for up to 6 months)
control/ supression oestrus behaviour

Question 3

What are the effects of giving FSH

Answer 3

Stimulates antral follicle growth - superovulation (but must administer early in follicular wave)

Question 4

hat are the effects of giving exogenous LH

Answer 4

Stimulates final maturation of follicles, luteinisation and provides luteal support
treatment of cystic ovaries in cows and heifers

Question 5

Name an exogenous LH drug

Answer 5

There is no LH specific product - so use HCG instead as has LH like activity

Question 6

What effect does giving progestogen have

Answer 6

supresses the hypothalmic-gonadal axis
used as method of inducing/ synchronising oestrus by administration and withdrawal of the product

Question 7

What are progesterone antagonists used for

Answer 7

This will displacr progesterone from its receptor but produces no signal
used for termination of pregnancy in the dog

Question 8

What are oestrogens used for

Answer 8

in practice not used for ‘reproductive’ considerations but is used for control of urinary incontinence

Question 9

What are prostaglandin F2A used for

Answer 9

Lysis of mature CL causing progesterone to decline
used to:
terminate luteal phase and synchronise oestrus
induction of abortion
induction of parturition

Question 10

What are the effects of prolactin inhibitors

Answer 10

removes the support for CLs, cuasing the demise of the CL’s, therefore termination of luteal phase and progesterone declines
is used to terminate pregancy and treat pyometra

Question 11

What are the effects of melatonin and how is it used

Answer 11

Give melatonin to a ewe = brings on cyclicity / oestrus
Give melatonin to a mare / cat / ferret = suppresses cyclicity / oestrus

Question 12

What are the clinical uses of oxytocin

Answer 12

Initiation of strong, regular and purposeful contractions of uterine muscle to facilitate parturitions (require fully dilated cervix)
Promotion of involution of post-parturient uterus
Aid passage of retained placenta
Promotion of milk let-down in agalactia