2. cyclicity across the species Flashcards
what are the functions of FSH
- follicular recruitment and growth
- oestrogen production
what are the functions of LH
- follicular dominance
- ovulation
- production of oestrogen and progesterone
the luteal phase is characterised/terminated by
- characterised by increaseing progesterone which remains elevated for >10 days
- luteal phase is terminated by luteolysis enabling a new follicular phase which culminates in ovulation
discuss the oestrus cycle in the bitch
- have an extended luteal phase
- regarless of if pregnant
- progesterone peaks then slowly declines followed by period of anoestrus
compare the hormone levels in a pregnant vs non-pregnant bitch
- progesterone only slightly greater in pregnant dog from day 21
- therefore cannot tell difference between pregnant and non-pregnant before 21 days by progesterone test
- rapid fall in progesterone occurs at partuition
- progesterone still decreases as pregnancy continues, so prolactin increases to help maintain CL
how is termination of the luteal phase achieved in the bitch
- repeated administration of a prolactin inhibitor but only when prolactin is principal luteotrophic hormone (if progesterone dominant, doesnt work)
- termination of luteal phase leads to anoestrus in dog (not follicular phase)
what is the role of prolactin in the bitch
- the early CL is autonomous
- from day 21 progesterone concentrations start to decline
- prolactin is the principal luteotrophic hormone
- declining progesterone stimulates prolactin secretion which in turn results in support of the CL and maintenance of progesterone
- despite this progesterone concentration continue to decline
- progesterone only produced by the CL in the ovary in the bitch and queen so ovariectomy during pregnancy will result in pregnancy loss
every non-pregnant bitch has which hormone and clinical signs in the luteal phase and why
- elevated progesterone => mammary enlargement and potential for milk secretion
- elevated prolactin => milk production and behavioural changes typical of pregnancy
- this is because it helps to help raise puppies from other bitches in the pack
cats have which kind of breeding pattern
- seasonal long day breeders
- polyoestrus
- induced ovulators
cats reach puberty when
onset influenced by season
- sometimes time from birth to puberty varies and can be <6months. if born september will have to wait until long day
wild cats have repeated oestrus signs between which months
march to october
discuss ovulation in the queen
- require stimulation of mating to ovulate
- if no stimulation, no ovulation
- absence of ovulation = regression of follicles
describe cyclicity in the cat
- cats will have repeated oestrus with no luteal phase
- if not mated, follicle regresses and a new follicular wave develops
- average interval between oestrus is 16-21 days
mating in the queen in oestrus will cause which hormone to surge
LH –> leads to ovulation
how does the luteal phase occur in the cat
- once ovulated will have a long luteal phase
- if pregnant luteal phase similar to pregnant bitch
in the cow the corpus luteum is dependent on which hormone
LH
approximately how long is the luteal phase in the non-pregnant bitch
70 days
compared to the pregnant bitch, the luteal phase in the non pregnant bitch is longer or shorter
longer
in the second part of the luteal phase progesterone concentration are greater in non-pregnant bitch because
elevated prolactin secretions
if you administered a prolactin inhibitor to a dog on day 40 of luteal phase what phase would she enter
anoestrus
what would happen if you administered a ptolactin inhibitor to a bitch on day 12 of the luteal phase
no effect
what is the typical time between oestrus periods in a non-mated cat
16-21 days
