It is imperative that the reader understand that this article is strictly for information and educational purposes only.  Any diagnosis and/or test(s) must be performed by a qualified veterinarian.

     The owner should be one of the first people to notice that there is something strange with Fido.  Since a dog cannot talk our language, we have to talk theirs.  One of the first things that change when the dog is ill, are habits.  Many problems are asymptomatic (without clinical signs).  Habits, however, signal that the dog is his old self, or that something is wrong.  When a dog refuses, or limits, the amount of food he/she eats, is usually one of the first signs that there is a problem.
     We are going to concentrate on problems that have to do with the kidneys.  The kidney's have several functions, but the primary one is that of filtering the blood and extracting metabolic wastes and excesses, and voiding these wastes as urine.  Signs that the dog displays when there is a problem having to do with the kidneys are:  an unusual increase in thirst, increases in the frequency and/or volume that the dog urinates, a reluctance to urinate, a straining when urinating, and an abnormal odor or color of the voided urine.  Sometimes the owner just knows that something is wrong, even without any of these clinical signs.  A veterinarian is the only one that can tell you if there really is something going on that is not right.  They accomplish this through several different types of tests, the type chosen depends on what you, the owner, tells them about the dog's changed behavior or habits, and what they observe through examination of the dog.
     A urinalysis is a screening test that is performed to detect problems within the urinary tract, and some kidney abnormalities.  There are three primary methods for collecting urine from a dog for analysis.  One is a "free catch method" that, as it's name implies, is a manner of collecting the urine as the dog voids.  This is not a reliable way to collect a sample for testing for a bacterial infection, due to the increased probability of contamination of the sample.  Two preferred methods of collecting a sample of urine from a dog with limited risk of outside contamination are:
          1.  A sterile and flexible plastic tube, called an urinary catheter, is inserted through the urethra and into the bladder.
               (The urethra is the passage connecting the bladder to the exterior of the body.)
          2.  A small gauge needle is inserted through the abdominal wall directly into the bladder, and a sample of urine is withdrawn
               from the bladder into a syringe.  This procedure is known as cystocentesis.

     The urine sample can then be subjected to one or more tests.  A dipstick can be used to detect chemical abnormalities, it can tell the veterinarian if there is sugar, protein or blood present in the sample.  A refractometer is sometimes used in conjunction with the dipstick to measure how dilute, or concentrated, a urine sample is.   This particular test is referred to as the measure of the specific gravity of the sample.  Another test is that can be used is called centrifuging.  The sample is placed into a test tube, the test tube is sealed and placed into a centrifuge machine that spins the sample at very high speed.  This spinning causes a separation of material within the sample, and collects sediment onto the bottom of the tube.  A microscopic examination of this sediment helps the veterinarian to see the bacteria that may be present, or the inappropriate presence of a material within the sample (for example, blood cells).
     Blood samples may also be taken to measure the kidney's effectiveness in doing its job.  Two of the most common of these tests are
          1.  Blood Urea Nitrogen (BUN) - measures the kidney's ability to balance and remove nitrogen containing wastes from the
               blood.
          2.  Creatinine - a waste product of protein metabolism.

     It is important to note that studies are ongoing in veterinarian hospitals and universities.  Your veterinarian is best qualified to know the most recent developments in animal care.  Finding a veteriarian for your animals is every bit as important as finding a personal physician.  Your vet can be an important source to the better health and well being of that special animal in your family.