Dogs have been known to give birth to as many as twenty-six puppies in a single litter. Be that as it may, most dog owners sooner or later will be faced with the problem of pregnancy in their pet. This problem should be met with pleasant anticipation, for there is no reason why, on this account, the operation of an efficient household should be even temporarily disrupted.
The average duration of pregnancy in the dog is from fifty-eight to sixty-five days, with most dogs giving birth on about the sixty-second day. During this period the vigorous animal usually thrives without any special change in its normal routine and gives birth without any assistance. However, there are some principles and suggestions of which every conscientious dog owner should be aware.
The animal should not be bred before it has reached full maturity, that is, not before it is about two years old. The narrowest margin of highest safety in breeding is between the ages of about two and seven years. Animals bred beyond these specified limits are much more prone to the various disease conditions associated with pregnancy. Habitual breeders often may be bred safely after the age of seven because their constitutions have long become accustomed to the rigors of pregnancy. But with the ordinary house pet it is best to remain within the above mentioned range. This does not imply that animals cannot be bred without danger before the age of two or over the age of seven. Breeding is often accomplished beyond this range with perfectly good results. But the range mentioned is still about the safest for the ordinary house dog.
Female dogs come into heat twice a year, for periods of approximately three weeks. The heat period is easily recognized by the obvious enlargement of the external female organs and the persistent discharge of a variable amount of blood. Meticulous animals constantly clean themselves during this period, so that often no blood is apparent. But the owner will rarely overlook the enlargement of the female organs. During this period dogs also show a certain amount of restlessness and increase in appetite.
The female in heat will most likely accept the male dog during the second week of the heat period. Matings toward the latter part of this week are most likely to result in pregnancy. This means that the best mating time is from about the tenth to the fifteenth day of the heat period.
The male dog has certain peculiar structural characteristics that are related to copulation. There is a bone in the penis of male dogs that assists the animal in achieving and maintaining an erection. There is a so-called “bulb” in the male penis, which after entrance into the female swells enormously and causes these animals to be “locked” together after emission occurs. There is no pain or danger associated with this “locking.” Usually it lasts from a few minutes to a few hours, with the average time being about twenty minutes. The owner should not interfere at this point, but allow nature to take its course. Veterinary intervention is rarely necessary.