You not only need permission from your landlord, but you might also need a building permit from the Gemeinde Bauamt. If that is the case, whether you or your landlord, as the owner, would need to put in the application is another question. If you need a permit there will be fees attached. Of course.
To give you an idea, in my area anything that stands over 60cm needs either a building permit or written agreement from all neighbors bordering the property (or all living in a Quartier.) Non-permanent structures under 2 (or is it 4?) m2 and 2(ish)m high can usually be erected with signed agreement from neighbors, larger non-permanent structures and all permanent structures need a building permit. Be aware that one neighbor refusing permission nixes the project, unless you then go through formal chanels to apply for a permit. But that's here - your Gemeinde/neighborhood might be far more lax.
If you can get away with a simple neighbor's agreement, be aware that the usual objection to a dog house is noise - so when you put together your petition, make sure you are ready to discuss barking, as well as how long the doggies will be in the house, and whether the dogs will ever be there when you are away from the property. And do mention that this is only for the dogs' comfort, that they are indeed house dogs, will be kept warm and snuggly in the house at night, etc. (Tierschutz concerns might arise.) It might help to pop round to ask the neighbors to sign with the doggies in tow - when people see how lovely they are, they will be less likely to refuse.
But then you might get lucky, and find that you don't need any kind of permit. First step would be to speak to your landlord.
As for where to find a house - as mentioned Landi, as well as Hornbach and B/H have kits to make a wooden ones that looked pretty easy to assemble. If you need something bigger than a standard dog house, look into children's playhouses or small garden sheds - with some minor tweaking these might work.
You can also get dog houses from any of the big pet stores, such as these from Meiko:
http://www.meiko.ch/index.cfm?shopca...0354803FC0F4D3
But the best option might be to speak to Papa Goose, EF's own skilled handyman and problem solver - who is himself the proud owner of a small herd of labradors.
Good luck with your project.