The first thing that is convenient to know is how from a zygote (The cell resulting from the union of an ovum and a spermatozoon — including the organism that develops from that cell), the resulting cell from the encounter between the spermatozoid and the ovule which has been fertilized goes producing the subsequent cellular divisions and the changes that gradually operate in the embryo and the fetus, according to a rigorous calendar finally lead to the birth of a perfectly healthy puppy (or puppies). When you know with detail all the principal changes and the development of the embryo and fetus that takes place for 58 to 63 days of pregnancy, you can start taking into consideration other series of points.
- Why is it so hard to diagnose pregnancy in a bitch?
- Why is it difficult to calculate the number of puppies in the litter?
- Why should I have to take such and such measures to avoid the administration of certain products that can be toxic for the embryos?
- Or, how should I go preparing my dog for the moment of birth?
And you will be able to understand that it is possible that many breeders and dog owners – including myself – that take pride in being able to tell with total security if a female is pregnant or not by simply observing certain changes in her behavior.