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Reproductive cycles of the domestic bitch.
MedLine Citation:
PMID:  21055888     Owner:  NLM     Status:  In-Data-Review    
Abstract/OtherAbstract:
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.
Authors:
Patrick W Concannon
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Publication Detail:
Type:  Journal Article     Date:  2010-10-08
Journal Detail:
Title:  Animal reproduction science     Volume:  124     ISSN:  1873-2232     ISO Abbreviation:  Anim. Reprod. Sci.     Publication Date:  2011 Apr 
Date Detail:
Created Date:  2011-05-09     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  7807205     Medline TA:  Anim Reprod Sci     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  200-10     Citation Subset:  IM    
Copyright Information:
Copyright © 2010. Published by Elsevier B.V.
Affiliation:
Department of Biomedical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14850, USA.
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