Slide a clean, dry ladle under the dog as posturing for urination begins to collect the sample. Pour the urine into a clean, dry, preferably covered container. Refrigerate sample if you are unable to bring it to the office within a few hours.
Thoroughly clean and dry your cat's litterbox. It is helpful to use a liner as well. Place some unpopped popcorn kernels in the box. When your cat urinates, pour the urine into a clean, dry container. This is NOT an ideal sample since there is a large chance of contamination but it often can give us some useful information. Refrigerate sample if you are unable to bring it to the office within a few hours.
If you can't catch a sample...
One of our veterinarians can often obtain a urine sample by cystocentesis, which is the process of withdrawing urine directly from the bladder. If you anticipate using this technique it is best not to let your dog urinate for a couple of hours prior to the visit and to try to avoid any temptation to urinate on the way into the office. It doesn't take long to get a sample if there is urine in the bladder. Samples taken in this manner can be used for culture (to check for bacteria in the urinary tract) and are usually better for determining if there are abnormal cells in the urine when it is in the bladder since it doesn't pass through the urethra and vagina prior to being collected. Sometimes the bladder is too small to get a sample this way and we may need to keep your pet for a few hours to allow the bladder to fill. The procedure does not seem to be very painful (just the needle stick) and most dogs tolerate it very well.