Dog Owner's Home Veterinary Handbook.pdf - Mr. Walnuts

SEX AND REPRODUCTION • 453
embryonic loss are chromosomal abnormalities and fatal genetic defects in
the pups.
Pregnancy can be diagnosed at three to four weeks by palpating the bitch’s
abdomen. This should only be done by an experienced breeder or veterinarian.
Using ultrasonography, it is possible to diagnose pregnancy as early as 18
days after the first breeding, although most breeders wait until 21 to 28 days.
Ultrasounds are excellent for diagnosing pregnancies but tend to underestimate
the number of puppies.
Checking blood levels of the hormone relaxin may also confirm a bitch’s
pregnancy. This is done at about 30 days into the pregnancy. X-rays are usually
taken about 45 days into the pregnancy and are excellent for determining
how many pups are present.
If a bitch is found to be pregnant and later does not deliver puppies, one of
two things must have happened: Either her puppies were reabsorbed or she
miscarried (aborted).
Fetal reabsorption can occur at any time from fertilization through about
the 40th day of gestation. The products of conception are absorbed back into
the mother’s body. Some bitches exhibit malaise, fever, loss of appetite, and a
thin, bloody, or purulent vaginal discharge. In early fetal reabsorption, symptoms
usually are absent and the pregnancy and reabsorption go unnoticed.
Thus the problem is often mistaken for failure to conceive.
Abortion is defined as death of the fetus followed by expulsion of the products
of conception. Abortion generally occurs during the last three weeks of
gestation. The signs of abortion are vaginal bleeding and the passage of tissue.
These signs may not be observed if the bitch is fastidious and consumes all
expelled tissue.
A well-recognized cause of third-trimester abortions and stillbirths is brucellosis.
Herpesvirus is another cause of late abortions, stillbirths, a decrease
in the number of pups per litter, and female infertility. Occasionally, a bacterial
infection will cause an abortion. Culprit bacteria include E. coli, camphylobacter,
mycoplasma, and streptococcus. Drugs that can induce abortion
include corticosteroids and chloramphenicol.
Bitches who suffer repeated early pregnancy losses or abort on successive
pregnancies should be suspected of having uterine infection or a progesterone
deficiency. Progesterone deficiency (called hypoluteoidism) is caused by failure
of the corpora lutea of the ovaries to secrete enough progesterone to support
placental attachment. The condition recurs with subsequent pregnancies
and becomes a likely consideration when a bitch repeatedly fails to maintain
a pregnancy.
Causes of sporadic abortion include a serious illness with a high fever during
pregnancy (such as distemper or leptospirosis), violent activities such as
jumping from heights, a blow to the abdomen, and improper feeding and prenatal
care.