If a cat gets pregnant from a dog? - briefly
It is biologically impossible for a cat to become pregnant by a dog due to significant differences in their reproductive systems and genetic makeup. This interspecies mating does not result in offspring because the genetic material of dogs and cats are too different to successfully combine and develop into a viable fetus.
If a cat gets pregnant from a dog? - in detail
The notion of a cat becoming pregnant by a dog is biologically implausible due to significant differences in their reproductive systems and physiology. To fully understand this, it's essential to delve into the intricacies of mammalian reproduction.
Mammals are divided into two primary groups based on their placental structure: epitheliochorial (found in dogs) and endotheliochorial (common in cats). The placenta is a temporary organ that develops during pregnancy to facilitate the exchange of nutrients, waste products, and gases between the mother and the fetus. The structural differences in these placentas indicate a fundamental divergence in reproductive biology between dogs and cats.
Furthermore, the mating process itself is incompatible between species due to differing anatomical structures. Canine copulation involves a "tie" or "lock," where the male dog's penis swells within the female's vagina, preventing immediate separation after ejaculation. This mechanism is not present in felines and would cause significant trauma if attempted with a cat. Conversely, feline copulation does not involve such a locking mechanism, making interspecies mating physically challenging and potentially harmful to both animals.
Even if fertilization were to occur against these biological odds, the resulting embryo would face insurmountable genetic barriers. The chromosomal makeup of cats (38 chromosomes) differs significantly from that of dogs (78 chromosomes). This disparity makes it impossible for the two species' gametes (eggs and sperm) to successfully combine, as the chromosomes cannot pair up correctly during cell division.
In summary, the reproductive systems and genetic makeups of cats and dogs are too distinct for successful interspecies pregnancy. The physiological barriers and anatomical differences effectively prevent such a scenario from occurring in nature or under controlled conditions.