Understanding Ovulation and Progesterone When Planning to Breed a Dog

May 24, 2021 9:33 pm Published by Leave your thoughts

Thinking about breeding your dog? If so, it’s time to get intimately familiar with your female dog’s ovulation and progesterone cycle. Understanding ovulation timing is the key to ensuring conception. While the entire heat cycle might last up to three weeks, the eggs are only viable for two to three days of that time. Here are tips from a veterinarian in Phoenix, AZ so you’ll know what to consider when breeding your dogs.


The role of estrogen is to cause a female dog to act receptive to mating. Estrogen levels rise anywhere from four to 20 days before ovulation, causing vulval swelling, changes in the dog’s vagina and bleeding. Estrogen doesn’t cause the dog to ovulate, and estrogen levels can only provide a rough estimate of when your dog will be fertile.


Luteinizing hormone, or LH, is what causes ovulation. LH levels will remain near zero for a while, then suddenly surge and drop again. Ovulation occurs two days after this happens. At that point, the eggs must mature for two days to be ready for fertilization. They only last two to three days after that. In other words, the LH peak is day zero, and then the eggs can be fertilized four to seven days afterwards. Once this window is over, the dog will not be able to conceive.

Testing for LH levels is the most accurate way to determine when your dog is ovulating. However, since LH levels may only be elevated for an 18-hour window, it’s best to try another method of testing.


Progesterone also tends to be at low levels—then it rises suddenly, which signals that ovulation is imminent. Progesterone levels tend to stay high for eight to nine weeks, or the length of a pregnancy, then they drop. If the dog is pregnant, the drop will induce labor. If she’s not pregnant, the hormone drop may induce false labor.

Testing progesterone is another effective way to predict ovulation. The initial rise occurs within a day or two of the LH rising—which means that when progesterone suddenly rises, your dog is in her fertile period. The progesterone level reaches five when the dog ovulates, and increases to the eight to 12 range when the eggs are mature. Typically, your vet will test progesterone levels every two to three days, rather than hoping they catch that magical 18-hour LH surge.

Your vet will probably use a blood test to check progesterone levels on day five of the heat cycle. Then they’ll draw blood every other day until they see the LH surge.

This is the most effective way of checking your dog’s fertility window. If you’re planning to breed your dog, it can help ensure the dog conceives right away. You’ll get much better results when you work with your veterinarian in Phoenix, AZ.

Christown Animal Hospital is happy to help you test for your dog’s progesterone and ovulation. Call us today to set up an appointment and get all your canine fertility questions answered.

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