Giardia is common here in Colorado. My vet gave my dog an initial shot for giardia and then a follow up booster. That was a couple of years ago and I thought it was wise to get the 2 shot series since she frequently drinks from streams and lakes as do most dogs. I was pleased that the dog did not get any giardia symptoms until I went back a year later for the annual giardia shot and the vet told me that the canine giardia shots had not proven to be very satisfactory & the vet was not giving them anymore as she considered it a waste of time and money.
So, I guess I have been lucky that my 8 dogs I have owned over 50 years have not had giardia symptoms as far as I know.
I do not know if Calif vets think giardia shots are of any value, but you might inquire.
