by Gemma Langerhuizen

Created on: January 03, 2007   Last Updated: July 14, 2010

Dogs,like other domestic species (especially the horse) will more often than not vary greatly in the signs of pregnancy they exhibit. Behavioural signs are most definitely NOT reliable, especially during the earlier stages of pregnancy.

Palpation is the most common method for determining pregnancy in the canine but this only has a fairly narrow time-period over which it is deemed reliable:

Abdominal palpation is usually done between days 25-29 after the first mating/insemination has occurred. Uterine swellings in the bitch are usually only obvious/distinct during palpation between days 20-35 after the successful breeding (as there is usually more than 1 mating this timing is usually done based on first attempt)which leaves only a 10-15 day window of opportunity. If upon first examination there are no discernible swellings then it is advisable to book a second consultation for the following week (this is often the case when the bitch has conceived at second or third mating instead of first).

The fetuses should be distinctly palpable as separate entities approximately 1 month after conception has occurred (roughly day 26-30). After this time, however, swelling of the uterus may make it almost impossible to feel any distinct swellings until approximately day 45-50 when the individual puppies should once again be discernible.

As with all diagnostic techniques, however, there is the possibility of false-negatives and false positives. False-negatives can frequently occur in the smaller breeds due to the difficulties posed by the average size of the fetuses and the small area available for palpation. Also, there is the possibility that the fetuses may be positioned towards the underside of the ribs making palpation difficult if not impossible.

Another cause of false-negatives can be small litter sizes or inability to palpate due to the bitch tensing her abdominal muscles. False-positives in the bitch are often common when there is an underlying problem (eg, a uterine infection such as pyometra) but these problems are usually associated with other more obvious symptoms such as: depression, lack of appetite, polydypsia/polyurea (excessive drinking/excessive urination) and often an unpleasant smelling vaginal discharge.

A much more effective way of diagnosing pregnancy is ultrasound (although this is usually more expensive) as this is useful for not only confirming pregnancy but diagnosing the stage of pregnancy as well. It is a non-invasive procedure(may require small amount of sedation) that can confirm pregnancy as early on as day 19-20. It will also give you a more accurate idea of the relative sizes of the puppies (which can be very useful for predicting if there are likely to be any complications with the birth due to size).

Fetal viability (likelihood of survival) can also be determined by ultrasound by paying close attention to heart beats from day 25-28 (normal is approx 200 beats per minute and an absence of a beat would show fetal death) and fetal movement from day 34-36.

Ultrasound is especially useful between days 32-45 as it is too late for palpation and too early for radiographs (x-rays). Radiographs are not useful until around days 45-50 as the fetal skeleton is not sufficiently developed enough to be seen clearly before this point. Radiographs are more often than not used to do 'puppy counts' (useful for whelping/birthing) and to check for any obvious skeletal abnormalities:

There are also several blood tests which can be done to confirm pregnancy in the bitch (eg, plasma relaxin concentrations which increase upon fetal implantation).

All of the above techniques should only be carried out by licensed professionals!

Learn more about this author, Gemma Langerhuizen.
Click here to send this author comments or questions.