After looking at a few insurers, I decided not to insure my dogs; I could not find a policy that made financial sense for us, given my dogs' ages and health histories.
Most of my dogs were too old to be insured at the time I adopted them (I believe Epona cuts off at 4 years old, Animalia cuts off at 7 - someone please correct me if I am wrong), or had a pre-existing medical condition/ genetic defect that meant most on-going treatment or future illness that could be deemed to be related to the condition would have been excluded from coverage.
For those that were insurable, the cost of premiums turned out to be higher than my annual veterinary costs.
I have found routine care to be surprisingly affordable here. Veterinary care for my young healthy dog runs maybe a few hundred a year (vacs, yearly check-up and the occasional visit for something one-off.). Also, my vet bills monthly so I don't have to pay at time of service.
But - specialist care can be quite expensive; one should be prepared. We've had a horrible few months here, needing frequent hospitalization and specialist treatment (and no happy ending

) and costs ran into the many thousands.
But YMMV. Look at the insurance policies carefully, speak to an agent to make sure you understand just what would and would not be covered - and then decide if insurance is right for your situation, or not.
Animalia:
http://www.haustier-versicherung.ch/
Epona:
http://www.epona.ch/german/chiens.html
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Do be aware, though, that in many cantons an owner is required to carry private liability insurance to cover any damage a dog might do. (For instance, in SZ owners must carry 3 Mio. coverage.) This is usually included in your household insurance policy, and generally runs CHF 20-50 per year.
Check with the folks at your Gemeinde as to what you are required to have, and then speak with your insurance agent.