Historical tradition
In the Russian language there are rules that separate the names into different types. Anthroponyms are names of people, names of nicknames of animals. It turns out that in the very rules of the Russian language laid the separation of names for animals and humans.
Earlier, when the Church had in Russia more influence to name animals human names was strictly forbidden. Every person's name is Holy. Give the dog a human name – is to insult the patron Saint.
There is another reason to give human names to animals is undesirable. Your family could be when a man with that name and it turns out that you thus insult the memory of our ancestors, if you call your kitty, Masha, and the yard dog Danko. It turns out that the name human name is belittled and ceases to mean anything, either.
The ethical side
There is another reason why it is undesirable to give the animals human names. For example, no one is immune from the fact that one day your son or daughter brings home her lover, whose name coincides with the name of your pet, so better not to risk and to call their Pets traditional names.