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Canine Reproduction Information Index


Monitoring pH, (Power of Hydrogen) during estrus is vital to ovulation timing and conception, critical if you are inseminating with no stud dog nose on site...








The canine vaginal pH changes when the bitch comes “in heat” so it is all about sampling the vaginal mucosa to determine how her estrus cycle is progressing. Taking “smears” measures the pH from the beginning of her “attractive stage” to ovulation (release of her eggs) so you know when to inseminate or have the stud dog cover the bitch.


Even if you have a stud dog on premises, he may be overanxious or inexperienced so doing smears is the most reliable way to determine optimum time for mating. Any experienced “Reproduction Vet” can read the smears which, after having examined the bitch and evaluated the first sampling, he or she can follow her estrus cycle by smears you take to the veterinary office.  Note: Taking fresh smears to the vet (instead of taking the bitch) eliminates stress and the risk of upsetting her cycle. Another tip to the wise - trying to read home-testing kit smears yourself may be unwise.  Unless you are an experienced dog breeder, take at least every-other smear to the veterinarian to read and examine microscopically.


Obviously the stud dog’s semen should be tested prior to the mating or collection. If the semen has been frozen and stored at a reliable sperm bank, it will have been tested prior to freezing.


The Dynamics of Vaginal pH in the Bitch during Proestrus and Estrus

Vaginal secretions were taken from bitches of different breeds and ages during proestrus and estrus at the Veterinary Medicine University in Bulgaria. That 2014 fertility study used 16 bitches of different age and breeds. The Vaginal pH of each bitch was measured once daily, starting from the first day of proestrus when it was noted that pH values “were between 7.4 and 8.7” and the study observes “at the time of ovulation vaginal pH ranged between 6.5 and 6.8.


The optimal time of breeding or inseminating ovulatory bitches was within 2 to 3 days after (ovulation) because of the dynamics of vaginal pH in the breeding bitch during proestrus and following estrus. Reference >


It is also important to note that the too-common practice of treating a breeding bitch with antibiotics as a “precautionary” measure prior to breeding is inadvisable. The uterus was once considered sterile in order to sustain a successful pregnancy but that concept was blown away by the observation that “the human placenta harbors a diverse microbiome.” Certainly that applies to other species.


The January 2019 NIH paper explains that “Canine endometrial and vaginal microbiomes reveal distinct and complex ecosystems” which are best left undisturbed unless there is actual infection. The canine uterus is actually a “complex ecosystem” but the absence of abnormal or harmful “germs” is likely attributable to the alkaline pH of the canine vagina.


For more on dog breeding information see this extensive CANINE REPRODUCTION INDEX in the net’s first and most authoritative dog-site and if you are serious about breeding dogs, explore the dog breeding information article below...

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Sunlight & Fertility

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Vaginal cytology and lab tests may track ovulation but a working stud dog and perceptive bitch owner can also track estrus.

Ovulation Timing

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Repro Vet says pregnancy depends on precise estrus timing.


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