Reproductive endocrinology in dog and cat

Question 1

follicular phase

Answer 1

oestrogen dominant

Question 2

luteal phase

Answer 2

progesterone dominant

Question 3

pro-oestrus

Answer 3

oestrogen dominant

Question 4

oestrus

Answer 4

oestrogen dominant

Question 5

metoestrus

Answer 5

transitional period

Question 6

dioestrus

Answer 6

progesterone dominant

Question 7

bitch

Answer 7

mono-oesturs
non-seasonal
polytocous
spontaneous ovulator

Question 8

Queen

Answer 8

seaonally polyoestrous
polytocous
induced ovulator

Question 9

bitch - endocrine events

Answer 9

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

Question 10

follicular phase - LH

Answer 10

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

Question 11

follicular phase - FSH

Answer 11

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

Question 12

follicular phase - oestradiol

Answer 12

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

Question 13

follicular phase - progesterone

Answer 13

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

Question 14

LH surge - timing

Answer 14

immediately after peak oestradiol level

initiated by decrease in E:P ratio

Question 15

estrus sex behaviour - timing

Answer 15

immediately after peak oestradiol level

initiated by decrease in E:P ratio

Question 16

ovulation

Answer 16

2 days after LH surge

oocytes ovulated are immature

Question 17

luteal phase

Answer 17

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

Question 18

luteal phase - LH

Answer 18

regulates progesterone secretion
GnRH agonist leads to luteolysis
GnRH antagonist leads to premature luteolysis

Question 19

luteal phase - progesterone

Answer 19

regulates CL’s ability to secrete progesterone
PR antagonist causes luteolysis
inhibit luteal PGF2a secretion
inhibit PGF-R

Question 20

luteal phase - PRL

Answer 20

regulates progesterone secretion from day 25
becomes essential luteotrophin from day 25 when it starts to increase
levels increase in non + pregnant animals

Question 21

luteal phase - endocrine events

Answer 21

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

Question 22

luteolysis induction

Answer 22

PGF2a at high doses
progesterone receptor antagonist
GnRH antagonist
GnRH agonist (continuously)
PRL lowering doses of dopamine agonist

Question 23

prolactin - bitch

Answer 23

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

Question 24

relaxin

Answer 24

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

Question 25

control of oestrus - bitch

Answer 25

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

Question 26

proligestone (PRG) properties

Answer 26

strongly anti-gonadotrophic weakly progestagenic antioestrogenic - controls vulval swelling + bleeding

Question 27

pseudopregnancy - bitch

Answer 27

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

Question 28

pseudopregnancy - bitch - treatment

Answer 28

synthetic progestagens - suppress PRL release oestrogens + androgens together (suppress PRL) dopamine agonists - inhibit PRL release

Question 29

endocrine events - queen - estradiol

Answer 29

during follicular phase, conc's are relatively high but variable

Question 30

endocrine events - queen - LH

Answer 30

copulation causes rapid release of LH from pituitary - usally multiple copulations needed to make sufficient LH for ovulation

Question 31

endocrine events - queen - progesterone

Answer 31

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

Question 32

endocrine events - queen - PRL

Answer 32

elevated for last 20 days of pregnancy + throughout pregnancy no changes in PRL levels during pseudopregnancy

Question 33

endocrine events - queen - interoestrus interval

Answer 33

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

Question 34

pseudopregnancy - queen

Answer 34

could occur after mating or spontaneous ovulation clinical signs are absence of oestrus NO mammary gland develeopment, lactation, or behavioural changes seen

Question 35

control of oestrus - queen

Answer 35

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

Question 36

control of oestrus - queen - progesterone

Answer 36

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

Question 37

hormonal control in dog + tom

Answer 37

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