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Ask the Veterinarian/vaginal cytology AI breeding


hi Sunday noticed blood
today/Thursday saw 25% cornified cells
testing again Saturday

does% indicate estrus  approximate what day should i do AI?  take a few days to ovulate and a few to mature right?

Hi Jim,
To be honest with you it's been years since I did any vagina cytology so I am not sure I can answer your question very well.

In proestrus, there are less than <50% of cornified cells. In estrus, this figure rises to >70%.

This is from the Merck manual:

"Owners of breeding animals should be advised to notify the clinic when they first notice that a bitch for which timing is planned is in season, based on vaginal discharge or vulvar swelling/attraction to males. Even the most astute owner may not notice the true onset of proestrus for a few days. Early proestrus should be documented with vaginal cytology (<50% cornification/superficial cells). A baseline progesterone level (usually 0-1 ng/mL) might be informative if the true onset of the cycle is unknown. Vaginal cytology should be performed every 2 days until cornification progresses significantly, usually >70% superficial cells.

It is useful to perform vaginal cytology every 2-3 days until cornification is complete (>90% superficial cells). This maximal cornification usually develops before the fertile period and continues until the onset of dietrus, which is usually a few days after the end of the fertile period.

Vaginal cytology may be continued until the diestral shift is identified, which gives a retrospective evaluation of the breeding just completed. In addition, at least 1 progesterone assay should be performed after day 0 is identified to document that levels continue to rise. This illustrates sustained corpus luteum function and strongly suggests that an ovulatory cycle has occurred. Insemination with extended, chilled semen should be done on days 4 and 6, or 3 and 5, after day 0. The days chosen can depend on overnight shipping possibilities and the schedules of all involved parties. Frozen semen breedings should be done on day 5 or 6."

Since I don't know what "day" of her cycle that she is in, that is about all I can tell you. You can always repost to one of the veterinarians in here.  

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Jana Connell RVT, CVT


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