We have H vaccinated every 3 years. This debate is discussed quite frequently. Some vets will only vaccinate every 3 years, some every year, and my vet mentioned that some where discussing the possibility of every 5 years.
It all depends on how you feel about vaccinations/over vaccinations, whether your insurance company are ok for you not to vaccinate, whether you put your dog in kennels......
In all honesty I would prefer not to vaccinate, titre testing has its positives (and its negatives), but after thinking about what I would do if I needed to board Hurley in kennels as an emergency I had him done. We will assess the next vaccination requirements next time round as there is an awful lot to think about.