National prevalence of Giardia infection in dogs and cats presenting to clinics with vomiting and/or diarrhea was examined using the IDEXX SNAP Giardia test kit. Veterinary practices across the United States were sent an invitation to participate in the survey and asked to use the test on fecal samples from the target population. The survey requested that the clinics report the results of 20 or more tests. A total of 21,092 results were reported, comprised of 16,114 dogs and 4,978 cats. Analysis of the data (excluding the handful of results reported from Puerto Rico) showed a Giardia prevalence of 15.6% among dogs tested, and 10.8% among cats. This difference was statistically significant (p < 0.001). Regional categorization into Northeast, Southeast, West, and Midwest drew out significant (p < 0.001) differences in prevalence in most cases for dogs; the differences were not significant for cats. These differences and other variables are currently being examined with this and additional data sets. We conclude on the basis of the SNAP test diagnostic that Giardia is a common enteric agent among dogs and cats with gastrointestinal signs.