I need help. I have 2 cocker spaniels (sisters). They are a year old. One Went in heat about 5 weeks ago and has been finished for about 2 weeks. As far as I know she has been around no males. I have a fenced yard and she has not got out. In fact the only time there out is when they have to tickle or to play with my children outside but tonight I noticed a couple stray dog near my house so I'm concerned. Since she went into heat I have been watching the changes in her body from begining to now. She now has more pronounced teats and she is still a little bit swollen, IS she pregnant? Can dogs mate through chain link fence in 20 minutes or less time? Are bigger teats Just a sign that she is maturing (a dog breeder I know sujested that)? When can a vet tell me if she is pregnant? Any advice would be welcomed.

Yes, they can mate through a chainlink fence, and a 'slip-mating' would be over in seconds. Was it her first season? Because the physical changes after the first season generally never quite subside - the vulva will remain larger than it was pre-puberty. And she is likely to have a phantom to a greater or lesser degree anyway.

What is a phantom and is it harmful to my dog?

A phantom pregnancy is when a bitch has physical reactions similar to those of pregnancy after a season, even when she hasn't been mated. It's a natural thing that happens with wild canines that have a pack structure. She may become 'broody', start nesting and produce milk at the time when she would have whelped if she were genuinely pregnant.

If she decides to have a bad one life will be unpleasant for her for a while, so keep an eye out for the symptoms. You could start giving her raspberry leaf tablets now until her 'whelping time' and give her lots of walks and an interesting life to 'jolly her out of it'.