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Anim Reprod Sci

Title:		Reproductive cycles of the domestic bitch
Author(s):		Concannon PW;
Address:		"Department of Biomedical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14850, USA. pwc1@cornell.edu"
Journal Title:		Anim Reprod Sci
Year:		2011
Volume:		20101008
Issue:		3-Apr
Page Number:		200 - 210
DOI:		10.1016/j.anireprosci.2010.08.028
ISSN/ISBN:		1873-2232 (Electronic) 0378-4320 (Linking)
Abstract:		"Domestic dogs are monoestrous, typically non-seasonal, polytocous, spontaneous ovulators and have a spontaneous luteal phase slightly longer (by approx 5 day) than the 64+/-1day luteal phases of a 65+/-1day pregnancy, a phase followed by an obligate anestrus before the next 2-3 week 'heat' (proestrus-estrus). The resulting inter-estrus intervals of 5-12 months are variable among bitches, commonly 6-7 months, and range from highly variable to regular (to perhaps within+/-5-10 day of sequential 7 month cycle, for instance) within bitches, and across studies and do not vary significantly between pregnant and non-pregnant cycles. Hormone levels reported are those observed in this laboratory using previously reported assays and canine gonadotropin standards unless stated otherwise. Endocrine sequences for dog cycles are not unlike those of many other mammals, including selection of ovulatory follicles by increased LH pulsatility, the occurrence of estrus behavior and LH surge during a decline in the estrogen: progestin ratio, a pronounced preovulatory luteinization as in humans and rodents, and luteotrophic roles for both LH and prolactin. Non-pregnant bitches have a spontaneously prolonged luteal phase, often longer and with a more protracted decline in serum progesterone than in pregnancy as there is no uterine luteolytic mechanism. The obligate anestrus of 8-40 weeks is terminated by poorly understood interactions of environment (e.g. pheromones, possibly photoperiod) and a potential endogenous circannual cycle in sensitivities of hypothalamic dopaminergic, serotonergic and/or opioid pathways"
Keywords:		Animals Dogs/*physiology Estrous Cycle/*physiology Female Gonadal Hormones/physiology Male Pregnancy Reproduction/*physiology;
Notes:		"MedlineConcannon, Patrick W eng Review Netherlands 2010/11/09 Anim Reprod Sci. 2011 Apr; 124(3-4):200-10. doi: 10.1016/j.anireprosci.2010.08.028. Epub 2010 Oct 8"