Do not give the uristat, that can cause problems for your dog. The clavamox dose would be too high, you would need about 375 or more mg from a viszla and the liquid is only 15 mg/ml. You can try to offer as much liquids as you can such as gatorade or water and encourage her to dilute her urine until you can get in tomorrow. Your vet may want to culture the urine and give a specific antibiotic depending on the test. If you give a dose of antibiotic it will interfere with the test results as well.
Let me know if you have more questions.
Dr. Debbie
Veterinarian
Full time practicing companion animal veterinarian.