Dear Dr. Thompson: Our 9-year-old lab has had her third bladder infection in the last four months. Each starts out the same. She has accidents and needs to go out more often and we start seeing blood. Our veterinarian has prescribed antibiotics each time and she gets better, but we are wondering why she has started having these infections so often.
ANSWER: Recurring bladder infections for the first time in a dog her age usually have an underlying problem that results in the symptoms you are seeing. An occasional bladder infection can develop, but when they keep coming back it warrants some further investigation.
The first step is to have your veterinarian evaluate the concentration of the urine. If she has an underlying disease that results in her drinking more or not concentrating her urine properly, her natural defenses may be affected. Kidney disease, diabetes, or other hormonal problems can all start out with increased thirst and urinations, but sometimes what people see are recurring bladder infections. If your veterinarian finds her urine to be too diluted or she has sugar or excessive protein in her urine, she will need further tests to determine the cause.
Bladder stones can also cause the recurring signs you are dealing with. The stones irritate the lining of the bladder, which you notice as bloody urine or straining. The stones also have a rough, porous surface and bacteria can attach or hide out on them. Antibiotics will temporarily relieve the symptoms but not fully clear the problem. An ultrasound of the bladder or an X-ray will normally find the stones. For larger stones, surgery usually is needed to remove them.
Unfortunately, older dogs can develop a tumor in the bladder. This tumor will bleed periodically and bacteria can stick to its rough surface, resulting in recurring infections. There is a screening test for the urine, but it has a number of false positives. An ultrasound is the best way to examine the lining of the bladder to evaluate if any tumors may be present. If they are near the top of the bladder and are small they can be removed with good results. If they are down toward the bottom or neck of the bladder your options may be limited.
If your veterinarian does not find another underlying cause, sometimes antibiotic-resistant bacteria may be developing. This does not occur as commonly as in people, but we do see increasingly difficult-to-treat bacterial bladder infections in pets. Your veterinarian will need to collect urine directly from the bladder to send to the lab to grow and see what type of bug is present and what antibiotics it may be susceptible to.
It takes a few days, but it will tell you exactly what type of antibiotic is the best choice to fully clear the infection. This problem can be frustrating, but determining the root issue will save you and your pet even more hassles.
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