A female dog can get pregnant when she is in the estrus (heat) stage of her reproductive cycle. This typically occurs when she reaches puberty, which can be as early as six months of age for smaller breeds but may be later, up to 18-24 months, for larger breeds. The estrus stage lasts about 5 to 13 days, and during this time, the female is most fertile and receptive to mating. Sperm can survive in her reproductive tract for up to a week, so pregnancy can happen at any point during estrus. Most dogs come into heat about twice a year, though this can vary by breed and individual dog.
In summary:
- Dogs can get pregnant starting from their first heat cycle at around 6 months or later depending on breed size.
- Pregnancy is possible during the estrus phase of heat which lasts about 5 to 13 days.
- Sperm viability in the female can allow fertilization for up to a week after mating.
- Heat cycles usually occur twice a year but vary.
The typical dog pregnancy lasts about 63 days following conception.