Ovulation Timing

The following interview was originally released as a podcast on July 31, 2014.

The topic is ovulation timing in the bitch with Dr. Scarlette Gotwals of Country Companion Animal Hospital in Morgantown, Pennsylvania. Dr. Gotwals received her DVM from The Ohio State University in 1983. She has a special interest in canine reproduction and has been involved with canine reproduction and semen cryopreservation for 21 years. She is a nationally recognized authority in these areas and serves as a consultant to veterinarians through the Veterinarian Information Network. Dr. Gotwals is a consultant for the Canine Reproduction Division of Zoetis.

This podcast is part of a special series of podcasts on canine reproduction in partnership with our corporate alliance, Zoetis.

AKC Canine Health Foundation (CHF): Dr. Gotwals can you please provide us a quick review of hormones involved in ovulation?

Dr. Scarlette Gotwals (GOTWALS): The first hormone of significance when a bitch comes into season is estrogen. Estrogen prepares the reproductive tract for breeding. It causes the vagina to thicken and diapedesis of red blood cells to occur. This is the part of the estrous period that is highly variable bitch to bitch. This estrogen period may be as short as 1 day or as long as 21 days or even longer. After the estrogen period the next hormone of significance is the Luteinizing Hormone or LH. LH is the biological trigger for ovulation in mammalian species which we denote as Day 0. Bitches ovulate 48 hours after the LH surge or day 2 post LH. What is unique about the dog is their eggs have to go through a further maturation phase post ovulation so their optimum fertile period is days 4, 5 and 6 post LH surge. The LH surge can be less than 24 hours or as long as 48 hrs. Without daily blood testing it would be easy to miss the LH surge. Fortunately we can use the hormone progesterone to accurately estimate when the LH surge occurred. Progesterone is baseline prior to the LH surge, begins to rise at the time of the LH surge and by time the bitch ovulates is in the 4-8 ng/ml range and by time the bitch is in her peak fertile period the progesterone is > 20 ng/ml and often in the 30-40 ng /ml range. The period of time starting at the LH surge until the end of the fertile period is very consistent between bitches.

More specifically, significant prior medical or surgical conditions should be discussed to determine what if any impact they may have on a pregnancy or lactation. What type of performance is she involved in? What is her body condition? More sedentary or overweight bitches will have more issues with fertility, ovulation rate and ability to whelp normally. Health testing of the male is also important consideration as well as general health, temperament, conformation, etc.

CHF: Gotwals how does the LH surge relate to physical changes the owner may see?

GOTWALS: Great question. Prior to the LH surge the bitch will have considerable edema, or swelling, and dark red bloody discharge. As estrogen drops and progesterone begins to rise at the start of the LH surge the edema will go out of the vulva and vagina. The owner may observe softening of the skin around the vulva and a change in the discharge from a dark bloody red to a more serum straw color secretion. This is variable so this may not be obvious in every bitch. If you are taking your bitch to a veterinarian for ovulation timing they will visually see a change from edematous to crenulation on vaginoscopy. Vaginoscopy is another tool a veterinarian uses to get a visual assessment where a bitch is relative to ovulation.

CHF: Are there behavioral changes related to LH surge?

GOTWALS: Yes. The day of the LH surge is often when there is a dramatic change in flagging behavior. I am sure a lot of breeders know what I am talking about. It is when a bitch wasn’t flagging when you went to bed but in the morning she is, or bitch wasn't flagging when you went to work but when you get home she is. This abrupt change is often on the day of the LH surge (day 0) or right around it. This is when fellow house mates will start mounting but the male is not that interested yet. Male dogs usually will intensify in their interest and go off feed and cry for the female days 4,5 and 6 post LH surge.

Intact females in homes where they are the only dog the owner may note that the bitch starts to walk around and whine a little, or the bitch may flag when someone bumps in to her.

This is something that is very useful for owners to record on bitches’ cycles that occur prior to breeding. Keep a record of first day of heat, day bitch starts dramatically standing and days where males are crying for them. Also good to record the first day where the female goes out or abruptly loses interest in breeding.

Generally when a bitch first starts standing she will be ready to breed starting 2-3 days later. No need for panic. When males are crying, off feed, and crazy for a female the bitch is likely in her optimum fertile period and ready to breed then.

CHF: How does LH surge relate to whelping date?

GOTWALS: Bitches whelp 65 +/- 1 day from the LH surge regardless of the day bred in the majority of breedings. The more accurately you pin point the LH surge at breeding the more accurately you can narrow down the whelping date. Large litters may come 1-2 days early and 1-2 puppy litters may go 1-2 days late.

Ideally a bitch bred optimally should whelp 60-61 days from breeding. Whelping dates can be used by the breeder to figure out in hindsight when the LH surge likely occurred. Bitches whelping at 58-59 days were almost bred too late and bitches whelping >62 days were bred early.

Another common cause of infertility is male factor infertility. Too few sperm, poor motility or abnormal sperm may all result in poor fertility. Semen evaluation of the male prior to a breeding is always recommended, but if it wasn't done before breeding and the bitch fails to conceive, it should be done after the bitch is determined to be not pregnant. Sometimes this can be overcome by intrauterine insemination or multiple inseminations, but in other cases, the infertility may be too severe.

CHF: How is this information used for planned C-sections?

GOTWALS: Bitches whelp in a fairly narrow window from LH surge. It is possible from the progesterone and LH values to plan a c-section date at the completion of the heat. In any bitch where a c-section is anticipated it is highly recommended to perform a series of blood progesterone levels at breeding. Remember bitches whelp from LH surge not the days bred. If a breeder is not in a position to do a complete progesterone level series there is still an added value running a progesterone level when the bitch starts flagging and again on the first breeding day. If the level is less than 5ng /ml another value should be checked a few days later. This data is valuable when calculating an anticipated due date. As a very general guideline we expect bitches to whelp 9 weeks from a progesterone level of 5-8 ng/ml.

CHF: You’ve talked about how important the LH surge is, but how do we pinpoint the LH surge?

GOTWALS: In breedings to highly fertile males or where semen count and quality is not an issue progesterone blood levels, and vaginoscopy can be successfully used to estimate when the LH surge occurred. Levels are typically in the baseline 20 ng/ml (even as high as 30-40+ ng/ml) during the optimum fertile period. There is variability from one diagnostic lab to another so important to know how your local diagnostic lab tends to run.

The dramatic change in Progesterone levels during the breeding period renders it an excellent tool for ovulation timing. There are however some bitches who haven’t read the book and can vary considerably from the expected levels. A veterinarian experienced with ovulation timing (OVT) can help identify these bitches.

The LH surge typically occurs over a 24 hr period but may be less than 24 hrs up to 48 hrs. When a frozen semen breeding is planned, or semen of poor quality is going to be used blood samples can be drawn daily and tested for LH. Typically progesterone levels are run every other day and serum saved from the days in between. Once the progesterone rise is documented the appropriately saved samples can be tested for LH. Progesterone levels need to be followed until ovulation is clearly confirmed (progesterone 5-8 ng/ml).

CHF: How does the length of bitch’s cycle relate to her fertile period?

GOTWALS: Typically, bitches are most fertile the last 3-4 days before they go out of heat. Bitches often follow a similar pattern each heat. So keeping records on every heat even when not breeding will help you be ready for the heat you do breed. Length of estrus is used as a generally guideline to know when to start progesterone levels.

Bitches who have very short heats where they are in and out in 7-9 days need to start testing by day 2-3 of the heat. These bitches often have their LH surge at the start of the heat and are ready to breed by 4-5 days in.

Bitches that are in 10-12 days need to start testing by 6 days in season. 14-16 days start by day 8. Bitches who stay in a full 21 days or longer can start later. Just be careful on any given heat or where you might have missed the first day of a heat there can be some variation. If the bitch starts flagging early than expected then get her in sooner for a progesterone level.

The more severe the inflammation or cystic change, the poorer the prognosis for fertility, and if the bitch does become pregnant, she will be at higher risk for resorption or abortion, or progesterone failure at the end of pregnancy. These bitches are also at higher risk for pre-term labor. Diagnosis is made via ultrasound or exploratory laparotomy, uterine culture and uterine biopsy (either surgical or with the endoscope). Treatment will depend on whether bacteria are present (antibiotics), chronic inflammation (steroid) or just CEH (nothing or surgical rupture of the cysts prior to breeding).

CHF: How does semen quality affect timing method?

GOTWALS: As a general rule stud dogs should produce 10 million sperm per pound of body weight and have >75% progressive forward motility with less than 20% miscellaneous morphologic defects. Since “normal” dog semen lives another 3 days in the bitch the better the semen quality the more leeway there is in ovulation timing.

Dogs can be acceptably fertile with much lower counts and quality if managed properly. As semen quality decrease the precision of OVT needs to increase.

OVT precision is increased by more frequent progesterone levels and adding LH testing for the most compromised semen.

CHF: What are the common pitfalls of ovulation timing?

GOTWALS: The most common error is stopping testing too soon. Sometimes breeders are so excited their bitch has come into season that they start checking progesterone levels too early and too frequently and by time the levels are getting into the critical diagnostic range the owner has financial or driving fatigue and stops checking levels. They may perceive a subtle fluctuation in baseline as “she’s going up” and don’t confirm the sustained rise with a significantly elevated value. They end up breeding too early and the bitch misses. The ideal time for timing is to get a baseline line level prior to the LH surge, one around the time of the surge and and continuing to monitor until ovulation is confirmed with a level > 5-8 ng/ml.

CHF: What are some final points a breeder consider regarding ovulation timing?

GOTWALS: Start observing and recording information on each heat a bitch has. Document day bleeding first noted, day she starts to stand and flag, when she is at peak standing (or males are crying for her), and when she goes out.

Use data to review with your OVT veterinarian to plan when progesterone levels should start. Share with your veterinarian the behavioral changes you are seeing. Be sure to check progesterone levels until ovulation confirmed.

Use whelping dates to look back over timing to see if everything first into place. Bitches generally follow a similar pattern each heat but not always. Often bitch family lines will be similar.

CHF: Thank you for your time and expertise, Dr. Gotwals.