Like it or not, your furry friend is a potential reservoir of infection for you. Multiple species of giardia exist: Some infect potentially any mammal, while other species are more animal-specific. Your doctor can make the best recommendation, but if you are a healthy adult, you are less likely to get giardia from your dog.
If your dog is having diarrhea, you should take her to the veterinarian for evaluation to diagnose the cause, which could be contagious. Your dog may be infected by drinking from a contaminated water source, which can infect you. Puppies and dogs in kennels appear to shed more giardia than sole-pet canines. Your dog may be able to infect you, although this transmission is not fully understood.