Mikhail Kasyanov has called it a "direct threat" and reported the video to the police.
Magomed Daudov said his leader's dog hates "hypocrites" and its "teeth itch."
Ramzan Kadyrov, who has previously condemned Apple, is now immortalized on an iPhone.
Journalist Elena Milashina says a family that came to her for help were forced to accept their teen daughter's wedding to a police chief, 47.
An opposition figure and friend of Boris Nemtsov called the official version of events a convenient lie.
Russian media outlets have been providing increasingly odd scenarios behind the death of the opposition leader.