OK, looks like somebody needs a little Estonian lesson 

 ::My   dog    ran       away    Mu   koer   jooksis   ära 

 ::This dog  is    mine    See  koer on    minu oma 

 ::So wherever you have gotten your conviction that 'mu' means 'mine' and not 'my', you are flatly wrong. 'Mine' in Estonian is 'minu oma', not 'mu'. So I also deleted absolutely wrong sentence in the article that mu koer is literally 'dog of mine'.