Metoestrus

• lasts around 90 days (in both pregnant and non-pregnant bitches)
• the corpus luteumLiterally means “yellow body” and is responsible for progesterone production within the ovary is present for a similar period of time regardless of whether the bitch is pregnant or not and, as such, Progesteronea steroid hormone secreted by the corpus luteum of the ovary that maintains pregnancy and promotes the development of the mammary glands. levels remain high in both pregnant and non-pregnant bitches

Progesteronea steroid hormone secreted by the corpus luteum of the ovary that maintains pregnancy and promotes the development of the mammary glands. primes the mammary glands to enable it to produce milk and is essential for the maintenance of pregnancy.  It also inhibits the secretion of LHLuteinising hormone; produced by the anterior pituitary gland and triggers ovulation and FSHFollicle stimulating hormone; produced by the anterior pituitary gland and stimulates maturation of the ovary prior to ovulation and therefore follicular development.  The early corpus luteumLiterally means “yellow body” and is responsible for progesterone production within the ovary appears to be somewhat autonomous (i.e. can produce progesteronea steroid hormone secreted by the corpus luteum of the ovary that maintains pregnancy and promotes the development of the mammary glands. without obvious endocrinological support).  However, from around day 20 after ovulationthe release of an egg cell (ovum) from the ovary in female animals, the production of progesteronea steroid hormone secreted by the corpus luteum of the ovary that maintains pregnancy and promotes the development of the mammary glands. starts to decline due to regression of the corpus luteumLiterally means “yellow body” and is responsible for progesterone production within the ovary.  During this phase, the hormone Prolactina hormone released from the anterior lobe of the pituitary gland that stimulates the secretion of progesterone by the corpus luteum and initiates and maintains lactation. is released from the anterior pituitaryThe front portion of the pituitary gland, which is found at the base of the brain gland.

Prolactina hormone released from the anterior lobe of the pituitary gland that stimulates the secretion of progesterone by the corpus luteum and initiates and maintains lactation. concentrations increase throughout the luteal phaseanother term for metoestrus and peak around day 63.  It is important to note that Prolactina hormone released from the anterior lobe of the pituitary gland that stimulates the secretion of progesterone by the corpus luteum and initiates and maintains lactation. levels increase regardless of whether the bitch is pregnant or not, although Prolactina hormone released from the anterior lobe of the pituitary gland that stimulates the secretion of progesterone by the corpus luteum and initiates and maintains lactation. levels are 4 times greater in pregnancy than non-pregnancy (due to positive stimulation on Prolactina hormone released from the anterior lobe of the pituitary gland that stimulates the secretion of progesterone by the corpus luteum and initiates and maintains lactation. release from placental proteins).  If the bitch is not pregnant, Prolactina hormone released from the anterior lobe of the pituitary gland that stimulates the secretion of progesterone by the corpus luteum and initiates and maintains lactation. levels will decline after this point.  In the pregnant bitch, after parturitiongive birth, suckling stimulates further Prolactina hormone released from the anterior lobe of the pituitary gland that stimulates the secretion of progesterone by the corpus luteum and initiates and maintains lactation. production and then, after weaning, Prolactina hormone released from the anterior lobe of the pituitary gland that stimulates the secretion of progesterone by the corpus luteum and initiates and maintains lactation. levels decline.

Anoestrous

• follows on from metoestrus
• variable length (usually around 4-5 months)

During this stage, progesteronea steroid hormone secreted by the corpus luteum of the ovary that maintains pregnancy and promotes the development of the mammary glands. and oestrogena steroid hormone produced primarily by the ovaries that stimulates changes in the female reproductive organs during the oestrous cycle and promotes the development of secondary sexual characteristics. levels decrease to baseline values and Prolactina hormone released from the anterior lobe of the pituitary gland that stimulates the secretion of progesterone by the corpus luteum and initiates and maintains lactation., LHLuteinising hormone; produced by the anterior pituitary gland and triggers ovulation and FSHFollicle stimulating hormone; produced by the anterior pituitary gland and stimulates maturation of the ovary prior to ovulation levels remain low.  Prolactina hormone released from the anterior lobe of the pituitary gland that stimulates the secretion of progesterone by the corpus luteum and initiates and maintains lactation. is thought to have an inhibitory effect on the resumption of oestrus by a poorly understood mechanism involving GnRHGonadotropin release hormone; responsible for the release of FSH and LH from the anterior pituitary gland, LHLuteinising hormone; produced by the anterior pituitary gland and triggers ovulation and FSHFollicle stimulating hormone; produced by the anterior pituitary gland and stimulates maturation of the ovary prior to ovulation.  At the end of anoestrous, gonadotrophins (GnRHGonadotropin release hormone; responsible for the release of FSH and LH from the anterior pituitary gland, LHLuteinising hormone; produced by the anterior pituitary gland and triggers ovulation and FSHFollicle stimulating hormone; produced by the anterior pituitary gland and stimulates maturation of the ovary prior to ovulation) are produced at higher levels, stimulating follicular development, oestrogena steroid hormone produced primarily by the ovaries that stimulates changes in the female reproductive organs during the oestrous cycle and promotes the development of secondary sexual characteristics. production and the start of pro-oestrous.