The only vacuum cleaner that will properly lift pet hair from carpet is one with a rotating brush assembly, no amount of suction will lift hairs that are embedded into the carpet, you need the physical brush contact to lift them.
I have a new fangled `top o the range suck the pattern off the carpet `one but when I need to get the pet hairs up i dig out the ancient big windsock bag thing that my mam used back in the Boer war days....still working with the odd belt replacement! Now I dont know if they still make ones with the rotating brush but if they do...that`s yer only man.