Dear Dr. Debra,
About 3 months ago, someone dropped off a puppy that we decided to keep. We named her Susie and noticed that she was pretty small but has been getting bigger and bigger as I have been feeding her. I have since figured out she got bigger and bigger because she is pregnant. She had a litter of 6 adorable puppies yesterday.
I have never seen a male dog around, and my neighbor's dogs are all fixed. How should she have gotten pregnant? How far can a dog smell or detect that an intact female dog is around or in heat? What distance can a dog detect another dog in heat?
Roy B, Ohio
Thanks for your question about how far dogs can smell another dog in heat. This is really interesting dog behavior and the answer is fascinating.
As you may know, dogs reach sexual maturity anywhere between 5 months and 1 year of age, during which time they experience their first “heat” or estrus cycle and can become pregnant. Dogs will repeat their “heat cycles” about every 6 months, or twice a year.
Gestation in dogs is approximately 63 days, so Susie definitely became pregnant while she was living with you.
To get to the heart of your question, male dogs have excellent senses of smell and can sense an intact female in heat up to 3 miles away. Dogs have geographic territories, and they can generally detect any intact females within those boundaries. They are usually most receptive if the female in heat is within a couple of blocks, but it's not uncommon for them to travel longer distances.
I hope this helps!
With warm regards,