TOPIC 2 – PRINCIPLES OF THERAPEUTIC ADMINISTRATION OF GNRH IN VARIOUS SPECIES

Question 1

Induction of cyclicly

Answer 1

Jump start cyclic function, following parturition, illness or out of season
- involves manipulating the hypothalamic GnRH release, as most acyclicty is a result of dec GnRH
- Bo, estrus synch may be based on GnRH and Prostaglandin use
long term progesterone us may induce rebound effect

• in seasonal species, melatonin implants (sRu) and light programmes (Eq) can be sued to induce cyclicity

Question 2

Oestrus induction

Answer 2

o Mainly in bitches (due to long anoestrus – up to 6 months)àGoal is to shorten
this period so bitch comes into heat again as soon as possible o This is achieved by increasing GnRH level:
§ GnRH implant (short-term)
§ Cabergoline/bromocriptineàResults in PRL ‘blockade’ (PRL inhibits
GnRH release)
§ Mimicking effects of FSH and LH (eCG & hCG combination) – Also used
to induce cyclicity in post-weaning sows or pre-pubertal gilts