Your friend has misunderstood some of the provisions of the new Animal Welfare law (TschV, TschG).
There are indeed rules requiring an owner to keep certain species in multiples, as these are social animals needing the company of their own kind for their mental well-being.
This does not include dogs. While one is encouraged to provide regular contact with other dogs
if possible, and if in the best interest of the individual dog one is not required to keep multiple dogs.
(In fact, most landlords, many neighbors, and some cantonal dog tax schemes actively discourage multiple dog ownership... but that's a whole new discussion.)
You can find information on what is required for the species you wish to keep on the BVet website - look for the 'Tier Richtig Halten' series of brochures. (Hunde Richtig Halten, Katzen Richtig Halten, Meerschwein Richtig Halten, etc.)
http://www.bvet.admin.ch/tsp/index.html?lang=de
ETA: For those interested, the text of the TschG is here:
http://www.admin.ch/ch/d/sr/455/index.html
And the TschV here:
http://www.admin.ch/ch/d/sr/455_1/index.html
.