by Mark Silverio, DVM
Dealing with canine reproduction
can be a challenging and rewarding
experience. Breeding, pregnancy
and whelping can frequently take
place with a minimal amount of and
no veterinary intervention.
However, these events are not
always routine, and the breeding of
female dogs should only be
attempted by individuals who are
willing to put in extra time and
effort in caring for brood bitches
and to learn all they can about
canine reproduction.
Conscientious breeders will breed only bitches who have shown no signs of heritable disease and
have highly desirable traits in such characteristics as temperament, physical appearance or
hunting ability.

Normal beagles may go through their first heat cycle as early as six months, or as late as one and
a half years of age. They repeat the cycle every six to seven months. It is best to wait till the
second or third heat before breeding a young female for the first time. They tend to have less
problems and you get an idea of what the heat cycle will be for that particular dog.

The bitch should be brought to the veterinarian for a pre-breeding exam to check for infectious
disease (including Brucellosis, which is venereally transmitted) and internal parasites, and to make
sure she is properly vaccinated as she will pass on this immunity to her pups.

To decide when to breed, it is helpful to have some knowledge of canine reproductive physiology.
Proestrus is the stage of the bitch’s cycle during which one sees vaginal bleeding, an enlargement
of the vulva, an attraction by males; but the bitch will not allow mating. Proestrus
usually lasts 6 to 11 days. This is followed by estrus, or standing heat, which lasts 5 to 9 days. The
first day the bitch will allow breeding is the start of estrus and this stage ends when she will no
longer accept the male. Ovulation occurs in the middle or end of estrus, and the female’s eggs take
one to two days to be ready for fertilization. The simplest breeding tactic involves “teasing” the
bitch with any male dog on day 5 or 6 of Proestrus and repeating the procedure every two to
three days until the first day of estrus is determined. Then allow the bitch to be bred on her first
day of acceptance and continue to breed every second or third day until the end of estrus.

Some breeders worry that this will lead to fetuses of vastly different ages in one litter, but this is
not the case. All of the bitches eggs are released from the ovary over a 24 - 72 hour period, and all
will be fertilized over the same time frame, even if the breeding occurred over a nine or ten day

The most common cause for failure to conceive is poor timing. For these “problem” bitches, your
veterinarian can examine cells obtained from vaginal swabs to help determine what phase of the
estrous cycle the bitch is in. This is most informative if done every other day, starting on the fourth
or fifth day of Proestrus. A more accurate determination of the time of ovulation is possible if blood
progesterone level is checked. A sudden increase in progesterone will occur two to three days
before ovulation starts.

Artificial insemination (A!) may be useful if the bitch is cycling normally and the male is capable of
achieving ejaculation but other factors prevent natural mating. This is probably best accomplished
at the veterinarian’s office, where the doctor and staff collect the male’s
semen and, using sterile technique, deposit it into the female’s reproductive tract. Frozen semen
can also be used, if transportation of one dog to the other is impractical. Conception rates
following Al are lower than those seen with natural mating. Therefore, AI should be reserved for
those cases where natural breeding can not be achieved.

The normal pregnancy or gestation period lasts about 63 days. Pregnancy can be detected as
early as three or four weeks with ultrasound examination. You veterinarian may also be able to
palpate fetuses at that stage, but this is a less reliable method of detection. Radiographs (x-rays)
will not show fetal skeletons until 45 -50 days into gestation. It may be helpful to know the exact
number of puppies to expect at whelping time, so x-rays are still considered a useful tool.

In the last two weeks of pregnancy, the bitch should be provided with an area for whelping and
nursing her pups. Many breeders build a whelping box to meet certain criteria. It should be large
enough for the bitch to be down and still have room for a litter of puppies. The sides should be
high enough so that four to five week old puppies can not jump out. The wall of the box should
have a ledge near the floor to prevent a bitch that is lying down from crushing a puppy between
her and the wall. The ideal temperature for the box floor would be about 75 degrees F, which can
be accomplished with ordinary light bulbs.

The diet for a pregnant bitch should consist primarily or totally of a high-quality commercial dog
food. A diet balanced for feeding puppies will meet her increased demand for energy, protein and
minerals. The amount fed may be gradually increased during pregnancy, so that she may be
consuming 1 1/2 times as much at the end of pregnancy as she was at the beginning. (Two-thirds
of the growth of the fetus occurs in the last onethird of pregnancy). Calcium and other mineral
supplements should not be added to the diet already mentioned for normal pregnant bitches.
Those that have had eclampsia (caused by low blood calcium) after previous litters may benefit
from calcium supplements given in the last week of gestation and throughout lactation.

When unplanned matings occur, there are drugs capable of preventing or terminating pregnancy,
but none are considered very safe. Therefore, it is important to make sure you know when each
bitch is due to come into season and prevent “mismating,” rather than risk the dog’s health with
hormone treatments. Likewise, contraceptive medications are available that prevent a bitch from
going through Proestrus and estrus, in order to accommodate her owner’s schedule. However,
such agents have limitations, they can not be used for long time periods, they may affect behavior
and activity levels and are not recommended for use in brood bitches.