SA 1 Flashcards
Describe bitch puberty. why do you not breed on the first cycle?
6-12 mos (up to 24 mos)
larger dogs tend to reach puberty at an older age than smaller dogs
first estrus tends to be irregular
split heat on first cycle common (6 wks b/t heats, w/ ovulation during 2nd heat)
how do you enhance onset of puberty in a bitch?
house with other estrous females
canines are ____estrous and are ______ breeds (seasonality)
monoestrous
non-seasonal
on average, bitches have ___ estrus periods per year
2
what is the dormitory effect?
syncing of estrous cycles of bitches who are living together
tell me the length of diestrus in the bitch.
2 months (60 days)
tell me the length of anestrus in the bitch.
4 months
tell me the length of proestrus in the bitch.
9 days (0-27)
tell me the length of estrus in the bitch.
9 days (4-21)
during anestrus, the bitch is/is not receptive to mating.
not!!
what does the bitch’s external genitalia look like in anestrus?
small vulva (no edema)
tell me about what the sex hormones are doing during anestrus in the bitch
deep anestrus: FSH and LH low
towards end of anestrus: LH and FSH increase –> follicular development = increase in E2
if you did vaginal cytology during bitch anestrus, what cells would you expect to find?
parabasal cells, occasional small intermediate cells
you perform a vag cytology in a bitch. what stage of estrous cycle is this bitch in?
anestrus
tell me about bitch behaviour while in proestrus.
female not interested in male, but may be playful. male is DEFINITELY interested in female thoooo
tell me about what the sex hormones are doing during bitch proestrus
follicles are growing = increase E2
ESTROGEN PEAKS AT END OF PROESTRUS
progesterone is low until the end of proestrus
when do estrogen levels peak during the bitch estrous cycle?
at the end of proestrus
tell me about how a bitch’s external genitalia looks like during proestrus.
- serosanguinous discharge bc of diapedesis
- vaginal mucosa appears smooth bc of edema
- vulva swells (firm to touch) bc of edema
if we did a vaginoscopy during bitch proestrus, what would we find?
glistening mucosa
rounded edges (edema)
if we did vag cytology on a bitch in proestrus, what would we find?
- RBCs (maybe) and neutrophils (mostly PMNs)
- small and large intermediate cells
- parabasal cells
- superficial cells increase
you do a vag swab in a bitch and find this. what stage of estrus cycle is this bitch in?
proestrus
during estrus, the bitch is/is not receptive to mating.
is
tell me about what the sex hormones are up to during estrus in the bitch.
- E2 is declining
- P4 increases
- LH surge occurs
tell me about the external genitalia of a bitch in estrus.
vaginal discharge is straw-coloured
vulva softens
when does ovulation occur
during estrus
what produces progesterone?
follicles!
what is estrous behaviour triggered by?
a decline in estrogen
you do a vaginoscopy of a bitch in estrus. what do you find?
mucosa wrinkles bc of decreasing edema due to decline in E2
you do vag cytology of a bitch in estrus. what do you expect to find?
- increasing cornified cells (>90%)
- mostly anuclear cells
- no PMNs, no RBCs
- background of smear very clear
- cells may slough off in sheets (end of estrus)
you do a vag swab of a bitch and find these cells. what stage of estrous cycle in she in?
estrus
dogs ovulate a _____ _____. this is the same/different to other species.
what stage of meiosis is the oocyte in?
primary oocyte
different - most species ovulate a secondary oocyte
prophase I
what is the ramification of dogs ovulating a primary oocyte?
needs 2 days to mature and become a secondary oocyte that can be fertilized
this means bitches aren’t fertile until 2-3 days AFTER ovulation (they remain viable ~1 week after ovulation)
tell me about the behaviour of a bitch in diestrus.
NOT receptive to mating - no longer attracts males
tell me about what the sex hormones are doing during diestrus in the btich.
- E2 low
- P4 increases rapidly, peaking 3-4 weeks after onset of diestrus
you do vag cytology on a bitch in diestrus. what do you find?
- abrupt decline in cornified cells
- > 50% intermediate cells
- WBCs present (PMNs)
- parabasal cells
you do a vag swab in a bitch. what stage of the estrous cycle is she in?
diestrus
after ovulation in the bitch, what hormone predominates?
progesterone
tell me about the external genitalia of a bitch in diestrus.
vulva swelling decreases
true or false: the length of diestrus in a bitch differs between a pregnant and non pregnant bitch.
FALSE! they are similar (60 days or 2 months)
what cell is this?
parabasal cell
what cell is this?
intermediate cell
what cell is this?
superficial cell
what cell is this?
anuclear cell
true or false: serial sampling is required when a bitch is in proestrus.
true
this is from a vag cytology. what stage of estrous cycle?
early proestrus
this is from a vag cytology. what stage of estrous cycle?
late proestrus
this is from a vag cytology. what stage of estrous cycle?
estrus
this is from a vag cytology. what stage of estrous cycle?
estrus
this is from a vag cytology. what stage of estrous cycle?
diestrus
____ can be used to time ovulation in the bitch.
progesterone
true or false: progesterone during estrus is a canine specific feature.
true!!!!!!!
P4 reaches concentrations observed in other species only with a CL
tell me about E2, P4, and LH and how they interact with ovulation in the bitch.
E2 peaks during proestrus, triggers LH peak
LH peak occurs 1-2 days into estrus, initial progesterone rise occurs same time as LH surge
ovulation occurs 1-2 days after LH peak
tell me the levels of P4 before LH peak, day of LH peak, when ovulation occurs, and when oocyte is matured
before LH peak: < 1 ng/mL
day of LH peak: ~ 2 ng/mL
ovulation: 4-6 ng/mL
oocyte matured: ~15 ng/mL & >
tell me about serum P4 levels and the event is corresponds with in the bitch.
serum progesterone (ng/ml) - event
- <1.0 - anestrus or proestrus
- 1.0-1.9 - ovulation minus 3d
- 2.0-2.9 - ovulation minus 2d
- 3.0-3.9 - ovulation minus 1d
- 4.0-8.0 - ovulation
- > 10.0 w/ cornified vag cytology - ovulation plus 1-5 d
- > 10.0 w/ non-cornified vag cytology - diestrus
tell me how you breed dogs with bitch and stud in the same location.
present the female to the stud dog when she has been in heat ~7 days
breed every other day while the female is receptive
tell me how you breed dogs with fresh semen
breed on days 2 and 4 post ovulation OR days 4 and 6 post LH peak
tell me how you breed dogs with frozen semen
breed when oocyte ready for fertilization:
days 3-4 post ovulation OR day 5-6 post LH peak
when should you do vag cytology in a breeding bitch?
every other day
when should you start P4 testing in a breeding bitch?
when 60-70% cornified cells on vag cytology
how often should you test P4?
test every 2 days
when is peak fertility when compared to LH surge?
5-6 days post LH surge
when is LH surge and ovulation compared to cytologic diestrus?
LH: 8 days
ovu: 6days
when is the best time to breed when compared to serum p4 levels?
when serum P4 ~17-24 ng/mL
tell me about dog sperm viability for fresh, chilled, and frozen semen.
fresh: 48h up to 11 d
chilled: at least 48 h
frozen: 12h
what is the best option to suppress estrus in a bitch?
ovariohisterectomy (spay!!!!)
why is there a bunch of potential negative side effects when you spay a dog?
increase in FSH and LH when spay, loss of negative feed back, may contribute to negative effects
a female intended for reproduction requires 130-150 days after a cycle for… what? if <120 days, there is a potential for… what?
uterine involution/repair
infertility
after pyometra is treated medically, females come in heat before _____ days. therefore, delay of ___ is also indicated.
120
estrus
what’s the problem with using progesterone for estrus suppression?
no universally safe/effective protocol
androgens are not recommended for longer than _____ for estrus suppression.
24 months
what is the best option for estrus suppression? broad
GnRH agonists
what are some forms of progesterone that can be used to suppress estrus in the bitch?
- progestin (ex. megestrol acetate)
- medroxyprogesterone acetate (MPA)
- proligestone
how does progestin act to suppress estrus?
negative feedback on HPA axis
decreases gonadotropins in most species but not reliably in dogs
anti-estrogenic
when do you admin progestin to suppress estrus?
administered in anestrus/early proestrus –> prevents onset of estrus
what is important to know if you use megestrol acetate to suppress estrus?
don’t tx more than 2 cycles in a row
don’t tx at pubertal estrus
contraindicated in pregnant dogs (masculinization of female puppies), and dogs with DM
What is medroxyprogesterone acetate? when should you use it? what is important to know with this?
long acting progestin
use only in anestrus
side effects are common: uterine dz in 4-10% of females, increases incidence of mammary gland tumors
how do you use proligestone and what’s important to know about this?
anti-gonadotropic properties (progestogen)
can be used at any stage of the cycle
don’t use on pubertal cycle
uterine disease in <0.3% of females
> 95% effective
not yet in NA
how do androgens work to suppress estrus?
negative feedback on hypothalamus
binding of androgen receptors
reduced response to estrogens
what androgen can you use to suppress estrus? an example
Mibolerone
what is important to know about using Mibolerone?
- must be administered 30 days before onset of proestrus
- don’t use in pubertal estrus
- clitoral hypertrophy
- don’t use in pregnant females
- avoid in Bedlington terriers
- estrus return in ~70 days on average after cessation
- tx for up to 5 years is reported
how do GnRH agonists work to suppress estrus?
mimic GnRH with an initial LH and FSH stimulation (flare-up effect)
sustained exposure to GnRH, reduced GnRH-stimulated gonadotropin secretion through GnRH receptor down regulation and decreased receptor expression
what is the disadvantage with using GnRH agonists to suppress estrus?
brief estrus at the start of admin
how do you admin GnRH agonists?
sub q implant, anterior to umbilicus for ease of removal
how do GnRH antagonists work to suppress estrus?
pituitary block of GnRH receptors –> immediate suppression of gonadotropins
high doses required to compete with endogenous GnRH
what are the other names for a false pregnancy?
pseudopregnancy, pseudocyesis, galactorrhea
false pregnancies happen because…? when do they happen?
response to a decline in systemic progesterone concentrations
2-3 months after estrus
3-4 days after OHE
3-4 days after discontinuation of exogenous P4
true or false: intact female dogs have a low incidence of false pregnancies.
false!!! high incidence in intact females
65% on a regular basis
what happens in a false pregnancy with progesterone and milk production?
2 mo diestrus –> mammary gland development
serum P4 at end of diestrus is accompanied by prolactin = increased milk production
true or false: false pregnancy is related to pyometra.
false!!! it is NOT related to pyometra
what is the theory around false pregnancy and pack behaviour?
atavism or vestigial pack behaviour:
dormitory effect –> females in a pack cycle in synchrony, but only dominant animals breed, subordinate females help raise pups
what can you use to tx false pregnancies in dogs?
- megestrol acetate
- anti-prolactin drugs
is it a good idea to ue megestrol acetate to tx false pregnancies? why?
nope
- relapse after cessation of therapy
- contraindicated in females with DM or mammary tumors
- may promote development of CEH if given during diestrus
what are the anti-prolactin drugs and what are their MOAs?
Bromocriptine = dopamine agonist
- dopamine inhibits prolactin secretion
Cabergoline, metergoline = serotonin antagonist
- serotonin stimulates prolactin secretion
what happens if you treat a false pregnancy BUT the bitch is ACTUALLY PREGANANNANT?!!?!?!?
you will induce an abortion
