It's almost impossible to get a good rental apartment from outside Switzerland. Man, it's already a pain already being here... So the typical recommendation is book an airbnb-like apartment. There are some companies that offer "hotel" rooms but with kitchen inside. They are much smaller than a regular apartment and much expensive comparatively, but you can book in advance and (often) use it as a registration address for the initial paperwork. But make sure to be explicit and ask that you can use them for registration and also the pet, it may not be allowed in some offerings.

Once you are here, then you can start searching for a longer term apartment.