Reproductive endocrinology in dog and cat Flashcards
follicular phase
oestrogen dominant
luteal phase
progesterone dominant
pro-oestrus
oestrogen dominant
oestrus
oestrogen dominant
metoestrus
transitional period
dioestrus
progesterone dominant
bitch
mono-oesturs
non-seasonal
polytocous
spontaneous ovulator
Queen
seaonally polyoestrous
polytocous
induced ovulator
bitch - endocrine events
ovulates spontaneously at end of variable follicular phase (4-28 days)
follicular development regulated by FSH + LH which induce synthesis of oestradiol
LH + FSH secretion regulated by gonadotrophin releasing hormone (GnRH) from hypothalamus + steroids from ovaries
follicular phase - LH
mid/late anestrus - low levels, <1/ng/ml, occasional pulses 4-24h apart
1 week before proestrus - freq increases, pulses every 60-90 mins, 3ng/ml
proestrus - lower levels
late proestrus - peak levels, 8-15ng/ml
follicular phase - FSH
mid/late anestrus - levels are high, increase throughout anestrus
1 week before proestrus - modest increases
proestrus - low levels
late proestrus - occurs about 1 day after LH surge, modest increase in mean level
follicular phase - oestradiol
mid/late anestrus - levels remain low
1 week before proestrus - levels remain low
proestrus - increase throughout from 10pg/ml to 120pg/ml
late proestrus - peak levels 1-3 days before LH surge
diestrus - some secretion
follicular phase - progesterone
mid/late anestrus - levels low
1 week before proestrus - levels low
proestrus - slow increase, 0.2-0.8ng/ml
late proestrus - 2.4ng/ml at LH surge, 4-10ng/ml at ovulation
diestrus - peak levels 15-90ng/ml post ovulation
LH surge - timing
immediately after peak oestradiol level
initiated by decrease in E:P ratio
estrus sex behaviour - timing
immediately after peak oestradiol level
initiated by decrease in E:P ratio
ovulation
2 days after LH surge
oocytes ovulated are immature
luteal phase
progesterone increase + plateus in diestrus + declines rapidly at luteolysis
this profile occurs in non/pregnant animals
progesterone can’t be used to test for pregnancy
corpora lutea are only source of progesterone during pregnancy
luteal phase - LH
regulates progesterone secretion
GnRH agonist leads to luteolysis
GnRH antagonist leads to premature luteolysis
luteal phase - progesterone
regulates CL’s ability to secrete progesterone
PR antagonist causes luteolysis
inhibit luteal PGF2a secretion
inhibit PGF-R
luteal phase - PRL
regulates progesterone secretion from day 25
becomes essential luteotrophin from day 25 when it starts to increase
levels increase in non + pregnant animals
luteal phase - endocrine events
premature luteolysis = early abortion no known luteolysin FP receptor present + active PRL/LH receptor expressed in pregnant bitches, rapid pre-partum lueolysis due to feto-placental PGF release - essential for onset of parturition
luteolysis induction
PGF2a at high doses progesterone receptor antagonist GnRH antagonist GnRH agonist (continuously) PRL lowering doses of dopamine agonist
prolactin - bitch
levels of PRL are 4x more than non-pregnant
if PRL release blocked causes funtional demise of CL + abortion
clinical signs of pseudopregnancy seem to be associated with high PRL levels
relaxin
increased levels 21-24 days after LH surge
non-detectable in non pregnant animal
sole source is placenta, reaches 5ng/ml in late pregnancy
only specific pregnancy protein in dogs
can be used for pregnancy diagnosis
levels fall after birth but can be detected up to 30 days during lactation
increases with PRL
control of oestrus - bitch
ovariohysterectomy
hormonal control:
progesterone - cant use natural as it’s not orally active + short period of action
synthetic progestagens - effective, potential to induce GH secretion. proligestone (PRG) is effective. testosterone
proligestone (PRG) properties
strongly anti-gonadotrophic
weakly progestagenic
antioestrogenic - controls vulval swelling + bleeding
pseudopregnancy - bitch
behavioural and clinical signs of pregnancy can be seen
clinical signs associated with rise in PRL levels + are seen 6 weeks after end of oestrus
any event causing fall in progesterone
most cases spontaneously remiss
pseudopregnancy - bitch - treatment
synthetic progestagens - suppress PRL release
oestrogens + androgens together (suppress PRL)
dopamine agonists - inhibit PRL release
endocrine events - queen - estradiol
during follicular phase, conc’s are relatively high but variable
endocrine events - queen - LH
copulation causes rapid release of LH from pituitary - usally multiple copulations needed to make sufficient LH for ovulation
endocrine events - queen - progesterone
levels stay at base level until after mating induced LH surge
levels increase with ovulation + peak after 30 days
non-pregnant animal, levels decrease from here pregnant animal, levels maintained at elevated levels for 25-28 days
if ovulation occurs but no pregnancy, don’t return to oestrus until after levels of progesterone have fallen to baseline
endocrine events - queen - PRL
elevated for last 20 days of pregnancy + throughout pregnancy
no changes in PRL levels during pseudopregnancy
endocrine events - queen - interoestrus interval
interoestrus interval of the queen may be useful guide to whether ovulation or conception has failed to occur
unmated queensn or queens that fail to ovulate have interval of approx 21 days
mated queens that ovulate but don’t conceive have interoestrus interval of approx 50 days
pregnant queens has interval of 65 days (gestation length)
some unmated queens can have 50 day intervals due to spontaneous ovulation
pseudopregnancy - queen
could occur after mating or spontaneous ovulation
clinical signs are absence of oestrus
NO mammary gland develeopment, lactation, or behavioural changes seen
control of oestrus - queen
ovariohysterectomy
hormonal control:
hCG - induces ovulation + delay subsequent as causes pseudopregnancy
androgens - androgenic anabolic steroids can be used daily to postpone calling 30 days before anticipated oestrus - causes masculinisation
control of oestrus - queen - progesterone
prevention - given at first sign of calling, suppress call + prevents conception
temporary postponement - given in anestrus will postpone following natural stages
permanent postponement - repeat doses in anestrus
only orally administered
hormonal control in dog + tom
regulation of testosterone production is the same as other mammals - LH stimulates leydig cells to release testosterone
LH regulated +vely by hypothalamic GnRH + -vely by testosterone
