That is definitely a common cockchafer. There is an almost identical specimen
here.
What I've been able to determine is that they're harmless, if a bit alarming. They're known for being quite loud flyers (they buzz noticably) and very clumsy too. Does your furry friend have a habit of crashing into walls and the like?
If you're interested, they are indeed related to scarabs (as well as june bugs and some other common pests) and the adult form is pretty harmless.It's a leaf-eater, but generally goes after either oaks or conifurs, so unless you have one of those trees in your flat you should be alright. They only live a few weeks, so your infestation will be fairly short-lived.
The bad news is that if given a chance to mate, a female will lay around 80 eggs which will eventually hatch into the (much more destructive) grubs, although the full development cycle takes 4-5 years. They go after roots and underground vegetation and the preferred area for eggs is under loose soil in the vicinity of such a food source; if you have nothing of that nature around you should be okay.
The Wikipedia article.