Amy,
It's fantastic that you are thinking of offering dog care services, there is a great deal of need for qualified dog sitters and carers - especially those who are able and willing to care for dogs with medical or other special needs.
Just a heads-up, though. Unlike just about every other country on the planet

, dog care is regulated here in Switzerland under the TSCV, and if you are considering setting up a commercial venture you may need to complete certain education courses and register with the cantonal veterinary office.
If you have any questions, contact the BVet to discuss what would be necessary given your specific business model.
Best of luck to you- there certainly is a great need for your services, and you should be able to do quite well.