Veterinary Voice: Progesterone Timing for Pregnancy Success

Dr. Marty Greer and host Laura Reeves talk about progesterone, that wonderful chemical inside our girl dogs’ bodies that tells us so much. Knowing progesterone levels is imperative for not only getting the bitches pregnant, but also keeping them pregnant.

“It’s really important from the beginning of the heat cycle to know when ovulation occurred,” Greer said, “because we know bitches are pregnant 63 days plus or minus 24 hours from ovulation. Normal pregnancy is not 58 to 72 days like we’ve been told for many decades prior to the time that we could do progesterone testing.”

“Get her pregnant and unpregnant by doing progesterone testing at the beginning of the breeding,” Greer said.

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Client handout regarding infertility:

Why isn’t my female pregnant? What can I do about it?

You did your homework – and have the perfect bitch, in her best condition and found the ideal male to mate her to. Both of them have passed all of the health clearances recommended for your breed. They have the temperaments you are looking for and their traits are complimentary to one another.

You know the most common causes of apparent or actual pregnancy failure are:

1. Poorly timed breedings
2. Poor semen quality and/or quantity.
3. Failure to maintain a pregnancy

Timing the breeding:

The timing of the breeding, based on progesterone levels (bred 2 to 3 days post-ovulation depending on semen type used), was just right. Most veterinarians recommend breeding 2 days after ovulation with fresh and fresh chilled shipped semen and 3 days with frozen semen. Ovulation is assumed to occur when the progesterone reaches 5 ng/dl (different units are used in other countries) with a range of 4 to 10 ng/dl. LH testing is also done in some clinics. LH, Luteinizing hormone, directly indicates ovulation, while progesterone is an estimation of ovulation. Progesterone is easier to measure and test as it can be done every few days, using human technology. LH requires daily testing and is canine specific.

Semen quality and quantity:

You know the stud dog had good quality and quantity semen – there was a semen analysis completed prior to shipping the semen. Your vet looked at it prior to inseminating your bitch and said the semen looked great, based on the sperm count (for a Bernese Mountain dog, the count should be 1 billion total), the morphology (shape and appearance of each sperm cell) and motility (how active and progressively motile it was on a microscopic evaluation).

Yet, she is not pregnant. Why? And if you try to breed her again, what can you do differently to improve the chances she will carry a litter to term?

First, we need to determine if she failed to conceive, failed to achieve fetal/placental implantation, or conceived and lost the litter. If you don’t have her ultrasounded, you won’t know if she failed to conceive or failed to maintain the pregnancy. A relaxin test or palpation is not adequate – these do not assess for fetal viability. This information is big piece of the puzzle.  When you are trying to justify the decision to do an ultrasound, this is the best reason to do so – this is not the place to scrimp.

If the ultrasound shows no pregnancy, and the semen and timing were good, then causes for failure to conceive or failure for fetuses to implant should be explored. These include:

• Was there a Semen quality assessment?
  1. Was the sperm count low?
  2. Was there abnormal semen morphology? Was the semen stained and assessed by a veterinarian?
  3. Was there poor semen motility? The semen needs to be progressively normal.
  4. Was there poor semen longevity? Holding a small sample of semen in extended in the refrigerator and reassessing it 24 and 48 hours later can be useful.
• Was there timing failure? This is a good time to review the timing of the breeding.
• Did she complete her ovulation?
  1. Failure to complete the ovulation. Did the progesterone testing continue past 5 ng/dl? If not, she may have not had a complete ovulatory cycle.
  2. Cystic ovaries? An ovarian cyst can interfere with a complete ovulatory cycle.
  3. Split cycle? If she failed to complete her ovulation, she may have split her cycle and will come back into heat in the next 4 to 6 weeks.
• Failure of adequate semen deposition: Fertile sperm must reach a fertile egg.
  1. If this was a natural breeding, was there a tie? Was the breeding witnessed? Was there a normal length tie?
  2. If this was a vaginal AI, was the AI performed correctly with no spermicidal exposure. Some lubricants and reusable equipment can have spermicidal properties. Using all disposable supplies is recommended.
  3. Does the bitch have a defect in her reproductive tract? Structural abnormalities causing failure of semen passage from the vagina to the oviducts including male and female anatomical abnormalities.
• Do either the male or female have Brucellosis? Canine brucellosis is a bacterial disease that can be spread venerally and can cause sterility in the male or female as well as pregnancy failure and early neonatal death.
• Was the bitch exposed to Canine Herpesvirus? – This is a viral disease that can cause early or late fetal death as well as neonatal death. In the adult, Canine Herpervirus causes mild respiratory disease. During early pregnancy, the fetuses can die at any stage, causing apparent failure to conceive if it is contracted during early pregnancy.
• Does the bitch have a bacterial infection in the vagina or uterus? A low-grade metritis, not rising to the level of a pyometra can interfere with conception. The difficulty here is that even in 2017, we cannot identify what normal bacterial flora in the reproductive tract is.
• Did she have another bacterial or viral disease that are not yet well characterized?
• Does she have a systemic illness? Any disorder that causes a fever can interrupt a pregnancy. Did she have a complete blood panel test, checking for signs of infection or organ disease? Consider testing for Lyme disease, Anaplasmosis, and Ehrlichia before you breed.
• Failure of the ovary to maintain progesterone high enough to support pregnancy (hypoluteoidism) Rarely, a bitch will have the inability to keep her progesterone level high enough to maintain pregnancy. This can occur as early as day 14 of the pregnancy. Testing her progesterone level at her pregnancy ultrasound can be an important tool.
• Does the bitch have abnormalities in her uterine lining? Cystic endometrial hyperplasia and fibrosis of the uterus can prevent normal placental development.
• Is there genetic incompatibility? If there are fatal genes, conception with pregnancy failure can occur. Line breeding dogs with too little genetic diversity can lead to small or no litters.
• Was there inadequate maternal nutrition?
  1. Raw meat diets can contribute to an imbalanced nutritional plane. Micronutrients and macronutrients must be adequate to maintain pregnancy. Bitches require carbohydrates to maintain pregnancy as well as to lactate.
• Does she have parasites? Parasite migration can lead to placental failure. The stress of pregnancy can lead to latent parasites starting to migrate again. Using Fenbendazole from day 40 of pregnancy to day 14 of lactation can protect the fetuses from this condition.
• Was the bitch subjected to trauma? Blunt trauma can cause the placentas to fail.
• Was the bitch subjected to undue stress?
• Did the bitch receive anesthesia, or inappropriate drug or hormones? Many of these drugs can be toxic to developing fetuses. All drugs should be avoided during pregnancy unless required to save the bitch’s life.
• Is the bitch Hypothyroid? Low thyroid levels can contribute to pregnancy failure or failure to conceive. This is a rare cause of pregnancy failure but should be considered if the levels are profoundly low.

If no underlying cause for failure to conceive is found, surgical breeding may be considered to improve the chances of success at the next breeding. Some bitches will conceive pups when surgical breedings are used to deliver the semen directly into the uterine body.

If the ultrasound shows a pregnancy was achieved but not maintained, this can result in fetal resorption (prior to day 45 of pregnancy) or fetal death and/or abortion (fetal loss after day 45 of pregnancy). This rules out poor timing, poor semen quality, or failure of semen to pass to the oviducts as causes for infertility.

Causes of failure to maintain a pregnancy include (see descriptions above):

1. Brucellosis?
2. Herpesvirus?
3. Bacterial infections in the uterus. Cultures should be taken and antibiotics used if bacterial disease is suspected.
4. Other bacterial and viral diseases that are not yet well characterized.
5. Failure of the ovary to maintain progesterone high enough to support pregnancy (hypoluteoidism). Serial progesterone levels should be run if hypoluteoidism is suspected.
6. Uterine lining changes that interfere with maintained placental attachment.
7. Inadequate maternal nutrition.
8. Trauma, stress, anesthesia or drug and hormonal interference.

A complete history should be taken. Diagnostics should include testing for brucellosis and Canine Herpesvirus. Cornell’s Veterinary Diagnostic lab has a blood profile called the “Canine Abortion Panel. Your veterinary clinic can submit tests for this. It is best done with paired samples, drawn 3 weeks apart and submitted together.

The pregnancy can be monitored for viable fetuses with repeated ultrasounds. Whelpwise_TM can be used to manage high risk pregnancies. Antibiotics, progesterone and terbutaline may be indicated if uterine irritability is shown to be putting the pups at risk. These drugs help quiet the uterus and can keep the pups safely in the uterus until they reach full term.

If no underlying cause for pregnancy failure or loss is found, uterine biopsy and cultures at about 60 days post-ovulation can be useful tools in determining if there is a treatable underlying cause and to help with determining a prognosis for future fertility. Treatment for causes suspected or found should be initiated prior to attempting the next breeding.

Fertility is never guaranteed. Your veterinarian can perform testing to assure you have the best possible opportunity to produce a litter.