Whether the bitch is bred or not, she should be confined during her period of heat. It is quite possible for one who has been bred to escape and be bred again by a stray dog. Such cases have been frequently known, some of the pups of such litters being thoroughbreds and some mongrels. No one puppy can
have two sires, but it is quite possible for the litter to be produced by the efforts of two males and for some of the puppies to be sired by each of the dogs.
The frequency with which a bitch may be bred is a subject of controversy. Some breeders who want production breed their matrons every time they come in heat. They ignore the fact that a bitch needs a rest period. If she is bred every heat, she has no chance to recover completely from whelping one litter before the next is on the way. Other breeders believe in mating every second heat, while still others skip every third period. I have found that either of these latter plans is satisfactory.
Be sure to make a note of the date of breeding. Then figure ahead sixty-three days and put a big red mark on your calendar, for this is the time you may expect the new arrivals. Puppies may be born a day or two either way of this date and still be normal, but since the period of gestation is so much shorter than in some of the other animals, much variation is dangerous. If your puppies should be more than two days late, you should consult your veterinarian—but be sure of your dates. I well remember my first litter which arrived, as I thought, one whole week late. It was not until months later that I discovered I had made a mistake in my calculations and that they were right on the day; but I went through enough suspense in that time to teach me to be more careful in the future.