Due to the peculiarities of a bitch's reproductive system, it is possible for a bitch to whelp, from a single natural mating, as early as 59 days and as late as 72. In order to derive the maximum benefit from scanning more that one scan is necessary. I offer repeat scans across the pregnancy to monitor progress.
* Interim scans are performed, either to ensure that a later conception will not be missed, or to follow up any perceived abnormality or possible abortion. It should be noted that the accuracy of final foetal numbers is not possible to guarantee.
It is relativity easy to count in the earliest stage how many foeti are present, however, some foeti will fail to survive and will either be reabsorbed (early in pregnancy) or mummified (later in pregnancy) and passed during the whelping process.
Single foeti are of particular concern as many of these pregnancies do not lead to a start of the whelping process. If not delivered, the foeti will die at around 66 days from mating. Knowing the date the pup is due becomes of paramount importance (see First Scan).
26 - 29 days from mating
To give likely whelping date and estimate of foetal numbers.
Dependent upon need
Clinically necessary scans may be performed in the interim period according to need (see below).
56 - 59 days from mating
To examine foetal size and presentation to enable decisions to be made once labour commences.