Summarize:

Your vet may give you a container in which to collect the urine. If not, use a container from home that you will not use again.  Shallow containers, such as aluminum pie plates, work really well for collecting urine from female dogs. Here are other container options:  Empty cream cheese container  Shallow food storage container A dirty container could contaminate your dog’s urine, making a urinalysis difficult to interpret. Once you’ve chosen a container, wash it with warm, soapy water. Make sure it’s completely dry before using it to collect the urine. With the container ready for use, put a leash on your dog and take your dog outside. Having your dog on a leash will make sure your dog can't get away when you try to collect a urine sample.  If you have a backyard, take your dog out to where she usually urinates.  Consider timing the collection for when you know your dog will need to urinate, such as first thing in the morning or after a meal. Pay close attention to your female dog as she gets ready to urinate. You may not have a lot of time to collect the urine once your dog starts to urinate, so make sure you’re ready to act quickly. You will slide the container between your dog’s back legs, so try to stand beside or slightly behind your dog. Collecting the urine should be a gentle but swift process. When your female dog squats and begins to urinate, approach her slowly. With one hand, gently slide the container between her back legs. Consider setting the container on the ground instead of holding it.  If you hold the container, you may get some urine on your hand. Have some disinfectant wipes or hand sanitizer nearby in case your hand gets urine on it. Make sure the urine gets in the container. You may need to reposition the container if the urine is hitting the ground. Let your female dog finish urinating before you move the container away.
Choose a container. Wash and dry the container. Take your dog outside on a leash. Let your dog squat to urinate. Position the container in the urine stream.