Part I of this series provided you with information about causes and symptoms of bladder infections. Part II addressed how to diagnose this common canine malady. This segment will discuss management of this disease. Those of you who have dogs with recurrent bladder infections will want to pay particularly close attention.

Management of first time offenders

For dogs experiencing their first bladder infection, the treatment of choice is a 7 to 14 day course of an antibiotic. Performing a urinalysis and urine culture is ideal, but antibiotic sensitivity testing really isn’t necessary with first timers as it is unlikely that the bacteria will have developed any antibiotic resistance.

The antibiotic chosen should be one that is known to be effective against bacteria that most commonly infect the urinary tract. Successful treatment is based on the resolution of symptoms along with normal urinalysis results and a negative urine culture performed two to three weeks following completion of antibiotic therapy.

Management of repeat offenders

For some dogs with bladder infections, the minute the course of antibiotics is completed, the symptoms begin all over again. With these guys it’s really important to do some diagnostic digging to hopefully hone in on and eliminate the underlying cause of their recurrent infections. In addition to the urine testing described above, this investigation begins with an extremely thorough physical examination (including a rectal examination) looking for any abnormality that might predispose to bladder infections. In males, such abnormalities might be an enlarged or painful prostate gland or an infection within the sheath (pouch surrounding the penis). In females, one should check for an infection in the skin fold partially covering the vulva.

If the physical exam and urine testing are not revealing, the next step is blood work (complete blood cell count and chemistry profile) looking for any clues. Specific testing to rule out Cushing’s Disease (a hormonal imbalance commonly associated with recurrent bladder infections) may be recommended.

Abdominal ultrasound comes next. This test allows inspection of the kidneys, the prostate gland, and the urinary bladder in search of stones, tumors, polyps, and anatomical defects. Unless they are significantly diseased, ultrasound does not do a good job imaging the “three U’s”: the uterus, the urethra, and the ureters (the ureters are the structures that transport urine from the kidneys to the bladder). Ultrasound creates no discomfort for the dog so sedation is usually not needed. Clipping the hair over the belly is necessary for good visualization (something the dog could care less about, but the human at the other end of the leash may object to). Buyer beware: the information gleaned from ultrasound is extremely user-dependent. This skill has a steep learning curve, and the more experience the ultrasonographer has, the greater the likelihood the results will be meaningful.

If all of the above testing does not reveal the underlying cause of recurrent infections, the final diagnostic steps are contrast studies (urethrogram, pyelogram) in which dye is used to visualize portions of the urinary tract not seen with ultrasound. These studies are performed using x-rays or computed tomography (CT scan).

Antibiotic therapy

The ideal way to manage recurrent bladder infections is to define and remove the underlying cause. In some cases, this underlying problem is not definable and/or treatable. When this happens, the judicious use of antibiotic therapy is key to keeping the dog comfortable and preventing issues that can arise secondary to chronic infection (bladder stones, spread of infection to the kidneys or bloodstream).

Choosing the most appropriate antibiotic regimen relies on multiple urine culture results including bacterial identification and antibiotic sensitivity testing. Just as in human medicine, some urinary tract bugs manage to develop a resistance pattern to multiple if not all antibiotics. Patients with such resistant infections are tricky to manage. They may need big gun antibiotics (many of which have significant potential side effects) or, if feasible, some “time off” from any antibiotic exposure with hopes that the bacteria will revert back to a more normal pattern of antibiotic sensitivity. If your dog has recurrent bladder infections, anticipate multiple urine cultures over time. Without these results a veterinarian is treating “in the dark”, and this is definitely not in the best interest of the patient.

For dogs with recurrent bladder infections, there are a two ways antibiotic therapy is typically managed:

Long-term, low-dose therapy

An antibiotic is selected based on urine culture results and the dog is treated at the standard dosage for 14 days. After 14 days, the total daily antibiotic dosage is reduced by 50 to 75 percent and is administered once daily at bedtime. This time of day is chosen because it precedes the longest stretch of urine retention (assuming the dog does not work the graveyard shift). This regimen will continue for months or even years, following a strict schedule of recheck urine cultures to verify the absence of bacteria. Long-term, low-dose antibiotic therapy is a safe and often effective means to manage recurrent bladder infections (in dogs and in people).

Pulse therapy

An antibiotic is selected based on urine culture results and the dog is treated at the standard dosage for 14 days. Just as with the protocol described above, a urine culture is repeated 7 to 10 days after treatment begins to make sure that the antibiotic has successfully eliminated the bacteria. If not, a different antibiotic is chosen and the process begins again. After 14 days, therapy is discontinued for three weeks after which pulse therapy is begun. This involves treating the dog with the antibiotic (at the standard dosage) for one week each month. There should be three-week, treatment-free intervals between treatment weeks. Pulse therapy may be continued for months to even years. Periodic urine culture results determine if a change in game plan is needed.

Additional therapies

Cranberry extracts may help prevent recurrence of some bladder infections. Cranberries contain compounds called proanthocyanidins (PAC’s) that prevent bacteria from adhering to the inner lining of the bladder wall. If the bugs can’t adhere to the bladder wall they are incapable of colonizing, multiplying, and causing infection. This PAC effect works only against E. coli, the bacteria most commonly cultured from canine bladder infections. Be aware that not just any cranberry formulation will do. Essential for success is the presence and bioactivity of PAC’s within the product. If interested in using cranberry extract, be sure to check with your veterinarian for his or her product and dosage recommendation. By the way, the notion that cranberries prevent infection by acidifying the urine is nothing more than an old wives’ tale.

Cranberry extracts may help prevent recurrence of some bladder infections

Probiotics may help prevent recurrent bladder infections. This is based on the notion that altering bacterial populations in the gut will alter bacterial populations in the feces. Given that fecal microorganisms that linger on the hair coat may be the source for some bladder infections, probiotics may (emphasis on “may”) have a beneficial effect. If you decide to try a probiotic get the most bugs for your buck by purchasing a product with the highest concentration of microorganisms.

Methenamine is a drug that may help prevent bladder infections. It is converted to a dilute formaldehyde product within the bladder where it acts as an antiseptic. Methenamine is effective only in a very acidic environment (the urine pH must be low). For this reason, it is often administered with a urinary tract acidifier.

Cleansing the skin area surrounding the vulva two to three times daily provides benefit for some female dogs with recurrent bladder infections. I recommend using baby wipes for this purpose. The hope is that the concentration of normal bacteria hanging out on the skin surface will be lessened, thereby lessening the likelihood of bacterial migration up into the urinary bladder.

If your dog continues to experience recurrent bladder infections despite your family veterinarian’s best efforts, I encourage scheduling a consultation with a veterinarian who specializes in internal medicine. Visit the American College of Veterinary Internal Medicine on line to find such a specialist in your neck of the woods.

Okay, time to lay it on me! If you are struggling (or have struggled) with a dog with recurrent bladder infections I want to hear from you. What have you tried? What has worked well and what has not?

Nancy Kay D.V.M.
Diplomate, American College of Veterinary Internal Medicine
Author of Speaking for Spot: Be the Advocate Your Dog Needs to Live a Happy, Healthy, Longer Life
Author of Your Dog’s Best Health: A Dozen Reasonable Things to Expect From Your Vet
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