Progesterone in Dogs: Assessment of Heat and Whelping

Martin For dog breeders, one of the most difficult parts of breeding can be identifying the right time to mate. Female dogs usually have just two seasons a year, and the fertile window can be very small. Even though a bitch might show bleeding and behavioural signs of heat for over 2 weeks, her fertile window might be as narrow as just a few days. progesterone testing is one of the ways breeders can identify this period.

Breeding during the fertile window

Progesterone testing is often a vital part of timing in dog breeding.
Progesterone testing is often a vital part of timing in dog breeding.

Chaguanas Breeders often travel long distances to mate their bitches, and a wasted trip can be expensive and stressful. Generally, male dogs will be able to tell when a bitch is receptive to mating, but this is not always accurate. Additionally, artificial insemination is becoming more popular in the dog world. Using this technique, it is particularly essential to know exactly when to inseminate the bitch, and there is no male dog present to sniff out the correct time.

http://sculpsureinwestpalmbeach.com/metronidazole At the other end of pregnancy, as whelping approaches, knowing when a bitch is going to whelp can be very helpful. While this can usually be estimated from the date of mating, some dogs might whelp earlier or later than others. In some breeds of dog, especially brachycephalic breeds like pugs and Frenchies, bitches can have great difficulty whelping. Owners instead sometimes opt for an elective Caesarean section. In these cases, timing is important, as too soon and the puppies might not be ready to be born, but too late and they could encounter problems.

http://lovegodlovelife.org.uk/page/84/ Progesterone measurement can assist in decision making in both of these circumstances. Progesterone levels begin to rise in bitches just before ovulation and remain high throughout pregnancy. A dramatic drop then occurs around 48 hours before parturition. Although progesterone tests usually require a blood sample, the information gathered is often well worth it.

Assessment of different methods of measuring progesterone

In 2010, Moxon et al. conducted a comparative study of three different methods of measuring the level of progesterone in blood samples from bitches. The Guide Dogs Breeding Centre takes blood samples from their bitches as part of their reproductive management, so it was a valuable opportunity. The study compared three methods, using radioimmunoassay (RIA) as the “gold standard”. The other two tests were a quantitative ELISA (Ridgeway Science) and a semi-quantitive ELISA. A total of 60 blood samples were analysed twice using the quantitative ELISA and the semi-quantitative ELISA and a further two samples were sent to two different labs offering RIA analysis.

Analytical results by all methods were categorised as low (<3ng/mL), intermediate (3 – 9.9ng/mL) or high (≥10 ng/mL). The two sets of RIA analyses were similar, with 22 or 23 samples categorised as low progesterone, 21 as intermediate and a further 17 or 16 as high. There was 100% agreement of the quantitative ELISA at low progesterone samples with the RIA results, 57.1% (12/21) agreement of intermediate samples and 76% of high progesterone with the RIA results. Likewise, for the semi-quantitative ELISA there was 95.5% agreement at low progesterone, 42.9% at intermediate and 100% at high progesterone compared with the RIA results.

Sensitivity, specificity, positive and negative predictive values and accuracy values were then calculated for each ELISA and are summarised in the table below.

ParameterCalculationQuantitative ELISASemi-quantitative ELISA
SensitivitySE=TP/(TP+FN)70.6100
SpecificitySP=TN/(TN+FP)10095.5
Positive predictive valuePPV=TP/(TN+FN)10073.9
Negative predictive valueNPV=TN/(TN+FN)7177.8
AccuracyAccuracy = (TP+TN)/(TP+FP+TN+FN)9089.2
TP: true positive, TN: true negative, FP: false positive, FN: false negative

Results

Overall there was 76.7% agreement of the quantitative ELISA with the RIA and 78.3% agreement between the semi-quantitative ELISA and RIA. The inter-assay coefficient of variation for the quantitative ELISA was 23.4% and 11.7% for the semi-quantitative ELISA.

The authors also calculated the theoretical costs of running one, five and ten samples per week for a year. If one sample was run per week the cost was comparable for each of the methods (between £686 and £738). This, however, excluded the purchase of a reader that was necessary for the quantitative ELISA. As the number of samples increased then the quantitative ELISA became the most cost-effective with an annual cost of £1133 for 10 samples per week, compared with £2640 for the semi-quantitative ELISA and £7280 for the RIA.

The RIA has the disadvantage of a longer turnaround time as the sample has to be dispatched and the results awaited. The semi-quantitiative ELISA will tend to be early in showing a high progesterone value and so several matings may be possible before the end of heat, whereas the quantitative will tend to show a high level later. To compensate for the latter the authors recommend that mating begins as soon as progesterone reaches 6ng/mL.

Conclusions

In short, progesterone measurement is a useful tool for bitch owners to time mating and as an indicator of whelping. Measurement requires a blood sample to measure the levels in plasma but the value is often worth the intervention. Veterinary surgeons offering progesterone measurement as a service subsequently have a choice of tests available. The quantitative ELISA is cost effective when a practice processes large numbers of samples each year, and when the practice has a plate reader.

Reference

Moxon R et al, 2010. Technical and financial evaluation of assays for progesterone in canine practice in the UK. Veterinary Record 167 528 – 531