I know this is a strange question, but does anyone know if there is a treatment (whether by pill or shot) to prevent a pregnancy that may have occurred? I have a pure bred dog and she just went into heat last night. I wasn't sure if she looked swollen or not last night, so I didn't want to board her up in a pin in the basement until I could tell for sure today if she was in heat. When I went out to check on her this morning, a random stray dog was mounted on her and they were "locked Up." I am not even sure if she could get pregnant this soon in her heat since it has just now been 24 hours into her cycle. She might not even be fertile yet. But if this dog did ejaculate in her and she is fertile, I was wandering if there is a medication that could keep her from conceiving. Something similar to the "morning after" pill for humans. If there is anyone reading this that is knowledgeable about dog breeding and could help answer my question it would be appreciated.

At one time there was an injection that was for use in cattle that was used as an "abortion shot" in dogs. This has since been taken off the market, and it had a tremendous number of side effects.
Generally, if the female is receptive, she is in full blown estrus. She may have had a "silent heat" up until now--no outward signs, but still going through the cycle.
I would suggest finding a vet who will spay her in early pregnancy. Just because she is purebred doesn't mean she should be used for breeding.

I am really confused because every time she has gone into heat in the past, she starts with the swollenness, and then about a week into it, she starts having the discharge and the blood. I thought that the time that she was fertile was during this time, not at the beginning when she has just started swelling up. I have never know her to have "silent heat" in the past. I also read that a dog isn't usually fertile until day 10 or so, and that the absolute earliest she could be fertile is at day three. She is just now through the first day. That is why I am hoping that she isn't pregnant. I also read that there are dogs who will take a male even though they are not in their fertile period. So I am not sure what to think. I love my dogs very much and they are both pure breds. I was waiting for her to go into heat so I could breed her with the male dog so that we would have a larger family. We have a lot of land and we love the two that we have, and I have had experience with raising big families of dogs, and we would love to have a litter of puppies to raise and let her be a mother to them. I realize that there are many opinions on breeding and spaying animals, and I feel that I am being responsible. I have a cat who I immediately neutered when he was old enough. Because I knew that he would be the only cat I wanted and I knew that I didn't want him around getting females pregnant and then having all these kittens to deal with. But with the dogs, its different. The dogs are my babies and I love them and treat them well, and I am not trying to sell litters to make money, I am doing it to preserve the blood line, and keep the ancestry of these beautiful pure breds going.

If you have any information on a dogs cycle and the concerns I had, I would appreciate any advice. I also thank you for your helpfulness and your advice,

My Sister Had This Same Problem So She Too Her Female Dog To Her Vet And They Gave Her A Shot To Prevent The Pregnancy And It Worked. Only Con Is You Have To Have The Shot Given In So Many Days After The Breeding (I Think It Was 3 Or So) Or It Wnt Stop The Pregnancy But Could Harm The Fetuses. Call Your Vet Asap To Talk To Them About This!