Some lodging websites now offer the option of special searches for finding a petfriendly accomodation e.g. in a B&B in the center of Berlin, Germany and other destinations around the world. Berlin is one of the most pet friendly cities in Europe, offering visitors a choice of over 500 hotels, B&B's and other accommodation choices starting from under 40 euros. There are pet friendly options available at every price level, from economy to five star.
However, travelers should note that just because a B&B is listed as pet friendly doesn't mean that they won't charge extra to accommodate pets. In fact, it's quite common in Berlin for properties to charge extra fees to pet owners so you should investigate this in advance before booking. Good websites will include this information in the general hotel information the provide. You can find your place to stay via wimdu which is an example of a useful website for searching apartments in Berlin.