The use of quantitative blood progesterone
estimations at specific times after the start of vulval bleeding
help to determine the best time for mating. This is very useful
in bitches with reduced fertility or those who have "missed"
on previous occasions due to unknown reasons.
Progesterone
(quantitative)
A blood sample should be taken
about day 7 post vulval bleeding. In most bitches the progesterone
concentration will be <3 nmol/L indicating that ovulation has
not occurred. If the progesterone level is above 6 nmol/L, ovulation
has occurred and depending on the actual level we will advise
when to sample again if required.
Interpretation
Progesterone <1.0 - 3.0 nmol/L Ovulation has not occurred, resample
3 -4 days Progesterone >6 nmol/L Ovulation has occurred, resample
again if required Progesterone 16 - 20 nmol/L Mate within 33
- 57 hours
Progesterone 20 - 38 nmol/L Mate within 9 - 33 hours
Progesterone >38 nmol/L Mate within 9 hours
Ovulation
detection in other species
Progesterone may be used to identify
that ovulation has taken place in a wide variety of species
by serial sampling to test progesterone concentration. Females
in anoestrus will normally have undetectable progesterone levels.
When ovulation occurs the progesterone rises and this rise can
be detected with a sensitive quantitative progesterone.
Detection
of Ovarian Tissue
Oestradiol
Oestradiol (E2) may be used to
detect the onset of oestrus in females or to detect ovarian
tissue in spayed females. A single sample may only be required
if the animal is showing signs of oestrus at the time of sampling.
In spayed animals it may be neccessary to do a GnRH
stimulation test to stimulate any ovarian tissue to produce
E2. Males with suspected sertoli cell tumours should be screened
with E2.
GnRH Stimulation
Test
1. Take a basal blood sample.
2. Inject i/v 0.32 µg Buserelin (Receptal, Hoechst). (A very
small volume of drug required (83µL) therefore it is advisable
to dilute the drug 1:10 with sterile water for injection and
then inject 0.83mL).
3. Take a further blood sample 3 hours later.
4. Label tubes clearly and request Oestradiol.
Interpretation
Males and females in anoestrus should have undetectable (<10.0)
levels of E2. Ovarian activity or abnormal testicular activity
will result in increased levels of E2. Sertoli cell tumours
in male dogs normally produce significant levels of oestrogens.
Each case must be carefully assessed and interpretation given
according to clinical history.
