Pyometra

Pyometra is a progesterone-mediated uterine disorder in bitches
and queens. Progesterone is the female hormone that works to
maintain pregnancy. All normal female dogs are naturally exposed
to tremendous concentrations of progesterone during the 45 to 75
days that follow the period of breeding (the period called
diestrus).

Progesterone places the nonpregnant uterus at risk for bacterial
infection. These bacteria are normally found in the vagina but
have infected the uterus by migrating through the cervix. A
bacterium called Escherichia coli is the most common cause of
pyometra in both bitches and queens.

The incidence of pyometra is thought to be greater in the bitch
than the queen because dogs are exposed to natural progesterone
more frequently than cats. An increased incidence of pyometra is
associated with estrogen administration in the bitch. Therefore,
estrogen should not be used as a treatment for “mismate” in
dogs. Administration of progesterone to queens can also
precipitate pyometra. Progesterone compounds should not be used
as anti-inflammatory or behavior-modifying drugs in intact
queens.

Pyometra can occur with or without vaginal discharge, depending
on the ability of uterine contents to flow through an open
(patent) or closed cervix. Closed cervix pyometra is more
serious because some of these dogs become ill before an owner
realizes there is a problem. In contrast, dogs with “open
cervix” pyometra can be recognized as having a problem earlier
because they usually have an obvious, malodorous, pus-colored
vaginal discharge before they become seriously ill.

Dogs with closed cervix pyometra may suffer from uterine
rupture, which can be as critical and life threatening as when
people have a ruptured appendix. In addition to the vaginal
discharge, the classic clinical signs of pyometra include
partial to complete loss of appetite, fever, lethargy, weight
loss, an unkempt appearance, vomiting and diarrhea, and
excessive thirst and urination. Blood and urine tests are
consistent with infection and may indicate involvement of other
organs that can be harmed by this severe disease. Abdominal
x-rays and ultrasonography can be useful in confirming the
diagnosis. Although it is rare, pyometra can occur in one
uterine horn with pregnancy in the other.

The best, least expensive, most reliable, quickest, and easiest
treatment for pyometra, after stabilization of your dog or cat
with intravenous fluids and antibiotics, is the spay
(ovariohysterectomy). This would not be the first and best
treatment only if your pet is younger than 6 years of age and a
valuable breeding bitch or queen. Medical treatment of open
cervix pyometra, using prostaglandin F2α. (PGF2α) and
appropriate antibiotics, has been successful in both the bitch
and queen. Antibiotics alone are almost never successful in
completely resolving pyometra.

PGF2α causes emptying of uterine contents and a lowering of
blood progesterone levels. The presence of live fetuses should
be ruled out by use of ultrasonography before treatment because
the drug causes abortion and because the treatment is not
usually successful if there are any remnants of previous
pregnancies in the uterus. Those dogs and cats should be spayed,
as should any dog or cat that is extremely ill. The PGF2α.
treatment should never be used for an extremely ill dog or cat.

Bitches and queens may need to be hospitalized for the
PGF2α treatment to enable administration of adjunct
supportive care, such as intravenous fluids and antibiotics, and
to permit monitoring of adverse effects and outcome of
treatment. The treatment protocol includes 5 to 7 days of
injections. Most can be treated on an outpatient basis because
dogs and cats treated with PGF2α should never be critically
ill.

Predictable physical reactions that occur after the
administration of this drug include restlessness, panting,
salivation, vomiting, diarrhea, urination, and dilatation of the
pupils (bitch and queen) and grooming, lordosis, and kneading
(queens). These reactions usually resolve within 5 to 60
minutes. After each subsequent injection, the reactions diminish
in severity and duration. Reactions are rarely considered severe
enough to warrant discontinuation of the drug.

A successful short-term response, defined as resolution of the
signs of pyometra, may not be evident at the completion of
PGF2α treatment. At the time of release from the hospital,
bitches and queens should have an improved appetite and normal
rectal temperature. However, the abnormal vaginal discharge may
be completely gone or may persist for another 5 to 10 days.

Reexaminations should be scheduled for 7 and 14 days after
completion of treatment. At 2 weeks after treatment, there
should be little or no vaginal discharge and the pet should be
otherwise healthy. Abdominal x-rays or ultrasonography can be
used to evaluate reduction in uterine size compared with that on
previous examinations.

Persistence of problems suggests that retreatment be considered.
A second series of injections for recurrent pyometra can be
successful and may be considered if the condition of the bitch
or queen permits. A successful long-term response is defined as
a return to normal estrous cycles and, if bred, conception and
carrying a litter to term.

Breeding at the next estrus is recommended to avoid potential
complications after progesterone’s effects on a nonpregnant
uterus. Prostaglandins do not resolve underlying uterine wall
disease. The overall successful conception rate after
PGF2α. treatment has been reported to be 40 to 82 per cent
in bitches and 85 per cent in queens.

The above is general veterinary information. Do not begin
any course of treatment without consulting your regular
veterinarian. All animals should be examined at least once every
12 months.