April 6, 2016
I thought we could talk about bladders today. Before you grit your teeth, let me say that it’s bound to be a lighter subject than body issues that lead to discussions of Milk of Magnesia or Preparation H. A far better organ system for public discussion. Bladders hold a deep fascination for my office staff. Instead of guessing how many jelly beans are in a jar, they often wait spell-bound to see how much urine that little dog can release on a waiting room plant. One client who frequents our hospital has a particularly clever little Yorkie who always manages to spray out a puddle despite our diligence and speed. Unfailingly, the good woman will say “My, he’s never done that before.”
Each day the kidneys filter the blood that flows through your veins, removing waste and impurities. Most of the blood continues to recycle to the rest of the body, but a small percentage of fluid and the filtered waste must be eliminated for continued good health. This fluid is called urine. In most mammals urine looks like a clear watery fluid, usually a shade of yellow, and is composed of excess body water, salts, and other waste. The yellow color is caused by the pigment urochrome, a breakdown product from hemoglobin. When dehydrated, the urine color may be darker yellow or orange as this pigment concentrates, indicating the need to drink more water. Each beat of the heart sends 20-25% of that blood flowing straight to the kidneys. Once urine is manufactured in the kidneys it travels from the kidneys via little tubes called ureters to the bladder, the holding tank in the body’s plumbing system. It is stored there until the pet voluntarily decides to empty their bladder, through another single tube called the urethra, to the outside. The act of emptying the bladder is called micturition or urination or voiding or peeing. Of course, all of these body parts can develop problems of their own, but the most common diseases revolve around the kidneys or the bladder. Kidney infections are not nearly as common as bladder infections, though often people confuse the two. Bladder infections may be caused by bacteria ascending up the urethra, because the bladder is the first stop from the “outside”. Today we will limit the discussion to dogs as the bladder problems seen in cats are often quite different in cause and treatment.
Prada’s Mom suspected a bladder infection when she observed blood in the urine. Female dogs are affected more often than males. Some affected pets may strain to urinate or may urinate very frequently or in unusual places. Although some dogs are depressed, Prada, a tiny snow-white Maltese, appeared bouncey and pain free. An examination was performed to determine if the bladder wall felt normal or was thickened. The bladder may have unusual “lumps” which could be cancerous growths or actual bladder “stones”, real rock-like growths that can fill the inside of the bladder. A urine sample was taken to analyze for bacteria, crystals, blood and other signs of disease. Sometimes the urine must be cultured to determine what kind of bacteria is affecting the dog and which antibiotic will best treat the infection. Because this was Prada’s second bladder infection in one year, a culture test was performed after obtaining her urine sample by cystocentesis, a sterile needle tap directly into the bladder. This method is preferred for a bacterial culture over a “catch” of urine because there will be no contamination from the pet’s hair or the environment as the sample is obtained. Chronic or repeat bladder infections may lead to the formation of bladder stones due to the chronic irritation of the bladder lining. These will require surgical removal in most cases. Bladder infections should never be minimalized as they can in turn ascend further up to the kidneys, which is potentially life threatening. Prada’s culture highlighted the best antibiotic choice for her and she responded quickly to her medication.
There is a small but significant obstacle to the pursuit and study of diseases of the bladder : obtaining the sample. Home catch, free catch, cystocentesis…. Apparently this has confounded veterinarians long before me! One very old veterinary text book neatly summed it up thusly : “Take about a dessert-spoonful of the dog’s urine (which you must use your own judgement how to obtain: place, for instance, a clean damp sponge at a spot where you think the animal will stale)…..”. Good to know I’m not alone!
Christine B. McFadden, DVM