four Phases Of Ovarian Cycle For Canine

Question 1

Proestrus

Answer 1

• 6-11 days (average 9 days)
• Vaginal bleeding occurs
• males are attracted to females but she is not receptive to breeding
• estrogen (dominant)
• 25pg/ml in early proestrus
• 60-70pg/ml in late proestrus
• peak plasma estrogen levels are at 24-48hours prior to the end of proestrus and beginning of estrus
• anatomical changes: enlargement of vulva, growth of mammary glands, thickening of oviduct and endometrium, glandular activity in endometrium, elongation of uterine horns, increased myometrial sensitivity, enlargement of cervix, edema and elongation of vagina along with a thickening of the vaginal walls

Question 2

Estrus

Answer 2

• 5-9days long
• vaginal bleeding has began to abate
• female shows signs of behavourial estrus allowing breeding
• progesterone dominant
• Surge in Luteinizing hormone
• effect of decreasing estrogen and increasing progesterone levels
• Corpora lutea forms
• novoulatory follicles, fluid filled corpora hemorrhagic or even cystic follicles may be present on the ovary
• uterus has increased in size and thickness
• may be palpable during abdominal examination
• appearance of the vulva is more flaccid

Question 3

Diestrus

Answer 3

• average of 56-58days in the pregnant female
• 60-100 days in the non-pregnant female
• begins when female no longer allows breeding
• Still progesterone dominant
• pregnant females have a higher level than non-pregnant females
• Corpora lutea is functioning if females have gone through estrus whether or not there is presence or absence of fetuses
• functions longer in the non-pregnant female than pregnant female
• Relaxin produced more in pregnant females
• Prolactin increases in the latter portion of diestrus (pregnant or non-pregnant)

Question 4

Anestrus

Answer 4

• duration of 4-5 months
• In pregnant females: begins anestrus with whelping, ends when proestrus begins
• Uterus undergoes repair
• Progesterone levels remain low during anestrus
• Estrogen levels fluctuates