I’m a dog lover.
Yes @Mahek ! We had a German Shepherd female that abandoned and even threw the puppy downstairs once she found it didn’t have hind legs.
In my opinion dogs do that to conserve resources, most importantly food (milk). In the jungle lionesses abandon their cubs if the food is scarce. Desperate times call for desperate measures and sometimes mothers will eat their offspring, an unfortunate event in the animal world. This type of cannibalism is called filial cannibalism .
Rats, along with other rodents are known to commit infanticide. They often have large litters of baby rats, or pups, which typically means that many of these young may be malnourished, sick or deformed. Mother rats may kill the weaker offspring in order to provide more resources to her healthier offspring.
Even for puppies many things are on first come basis. The strongest puppy will drink most of the milk by reaching first and also by pushing away others. Its Survival of the fittest!!.
Humans have a different value set. Such things appear strange even abhorrent to us. This is what makes us HUMAN!!!