Estrous Cycle Flashcards
Anestrus
Start with progesterone level
Duration
Starts at end of luteal period, progesterone < 1 ng/mL
Duration: 2-5 months, even up to 10 months
Anestrus
What is it?
Key hormones
Quiescent period for rest and repair of uterus
Controlled by HPG
Hormones: GnRH, FSH, LH
Anestrus
Hormone activity early to late anestrus
GnRH pulse frequency increases leading to production of both FSH and LH
What hormone stimulates follicular development?
When is it highest?
FSH
Greatest in anestrus
Relationship between FSH and LH
FSH increases LH receptors in granulosa cells in ovary
Proestrus
What is it?
Duration?
Time of development an maturation of follicle and oocyte
Duration: average is 9 days, range 3-14 days
Proestrus
Signs and what causes them
Increasing estrogen level
Swelling vulva
Serosanguinous vaginal discharge
Vaginal mucosal thickening
Attraction of males
Estrus
What is it?
Duration?
Time of final oocyte maturation, ovulation, breeding, receptivity, and conception
Average 9 days range from 3 to 14 days
Estrus
Hormone release
LH surge initiates estrus; ovulation a few days after
Corpora lutea formation; increasing progesterone
Estrus
Characteristics
Decreasing vaginal discharge
Reduced swelling and softening of vulva
Thickening edematous vaginal mucosa (preparing for breeding as well as uterus for pregnancy)
Standing for breeding
What must happen to an oocyte before fertilization?
Canine
Oocyte is ovulated with only one meiotic division
Second division is required before fertilization (takes about two days)
Diestrus
What is it?
Duration
Luteal period occuring after every estrus
Duration; 50-70 days
What is unique in canines in regards to progesterone?
Bitch has serum progesterone levels during diestrus which are fairly similar regardless whether bred or not and regardless whether pregnant or not
This is due to CL (in-tact for 2 months)
Pseudocyesis; what is it?
False pregnancy; normal in dogs does NOT indicate disease
Indicates ovulation plus development then deterioration of CL
Pseudocyesis clinical signs
Mammary gland development
Galactorrhea (lactation)
Abdominal distension
Nesting behavior
Feline Facts
Seasonally polyestrus (long day breeder)
Ovulation induced by mating (causes LH surge); will mate several times, ovulation rate based on mating frequency
Can cycle in and out of estrus frequently
Vaginal Cytology
Indirect indicator of serum estrogen level
Vaginal mucosal thickness will occur; 15-20 cell layers during estrus while it is only 4-5 cell layers thick during anestrus and diestrus
Cytology:
Cells from vestibule
Degenerated; no normal cell membrane or nucleus
Rolled appearance
Cytology:
Anestrus and Diestrus
Parabasal cells; healthy cells from near the basement membrane
Small cells, large nucleus with highly defined nuclear detail
Occasional neutrophils
No RBCs
Cytology:
Proestrus
Intermediate cells; cellular membrane integrity lost
Some parabasal cells
Very few neutrophils
Many RBCs
Cytology:
Estrus
Primarily superficial cells
Flattened degenerated cells with pyknotic nucleus or no nucleus
Cornified, keratinized, anuclear
Clear background due to increased fluid production
Some intermediate cells
Decreased RBCs
Rare parabasal cells and neutrophils
Blood contamination in semen
Where?
May come from: Surface of penis Prepuce Testes Epididymis Prostate Bladder Abdomen Penis Sheath
Blood contamination in semen
Why?
Potential infection
Surface vessels are very fragile
Blood contamination in semen
Quality of semen
Dimished because sperm adheres to RBCs
Blood contamination in semen
Breeding
Do NOT breed female until diagnostics are run on the semen
Also perform:
Physical exam (including prostate exam)
Urinalysis
Cytology of semen (bacteria? WBC? RBC? RBC:WBC)
Surgical Intrauterine Insemination
Semen deposited in uterine horns with IV catheter
Not done commonly
Can do an abdominal approach and inject right into uterine horn (want to make sure semen does not go out of cervix)
Sperm function after insemination:
Fresh or chilled semen
How often?
4 to 5 hours
Breed twice at start of fertile period and again one to two days later
Sperm function after insemination:
Fresh semen in uterus
How often?
9 to 11 days
Natural cover; usually done every other day
Sperm function after insemination:
Chilled semen in uterus
1 to 2 days
Sperm function after insemination:
Thawed frozen semen
Less than one day
Must be intrauterine
Done day 5 and 6 following LH surge
