Why A Urine Sample Is So Important
Do you have any idea how much information is in a tiny amount of urine?
Urine. Most people hear the word and think, "Blech". But do you know what urine is? Just part of the liquid portion of your blood. Water, proteins, electrolytes...not much, really. And as long as the organism creating the urine doesn't have a urinary tract infection, it's even sterile--no bacteria!
The best thing about urine from a veterinarian's point of view is this: it's not very good at keeping secrets.
To be perfectly frank, it used to annoy the p!$$ out of me that we as veterinarians were constantly recommending fecal checks (you know, that at-least-once-a-year poop sample we ask for) but rarely asking for routine urinalyses. Sure, those poop samples can let us screen for worms, some of which are contagious to people, but URINE! Urine, that magical fluid, can help us spot an amazing variety of problems before your pet is even showing symptoms!
Let's start with the most obvious: urinary tract infections. Did you know that it is very common for dogs, especially female dogs, to have bladder infections without ever showing signs? Urinary tract infections in dogs can lead to the formation of bladder stones ($5 word: uroliths) which can block the urethra so your dog can't urinate--a surgical emergency that I'm sure you'd rather avoid. An infection in the urethra can go up to the bladder and from there to the kidneys, too, where it becomes a life-threatening problem. And all this can be going on without your dog showing any signs until it is almost too late.
What else can we look for in urine? The short story: signs of diabetes, Cushing's or Addison's disease, kidney failure, evidence of liver shunts, crystals (especially common in cats), bladder cancer, and stones that AREN'T caused by infection (some dogs are genetically prone to this).
The easiest way to collect urine, in my opinion, is this: take a wire coat hanger and straighten it out. Form a loop in one end. Place a plastic sandwich bag (a clean one! Don't confuse your vet with bread crumbs!) in the loop, folding the edges over the wire and taping them so the bag stays in place. First thing in the morning, take your dog out on a leash, and slip the bag under the urine stream. You may want to walk around with least/wire loop a few times before you actually intend to collect the sample, just to get your dog used to this strange device. Often only one teaspoon of urine is all your vet needs, although if there are abnormalities in the urine, they may need to collect more.
Even very young animals can be prone to serious issues that could show up in the urine. I've seen puppies die from bladder stones due to undiagnosed infections, and changes in urine have helped point me in the right direction with patients that were in liver failure. So, even if your vet isn't asking for a urine sample, if I were you, I'd take one in every year with that poop! Hey, why not? In my opinion, an ounce of urine is worth a pound of poop! ;)