Canine Bladder Infections: Part III

Photo Credit: Susannah Kay

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.

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?

Best wishes,

Nancy Kay, DVM

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
Recipient, Leo K. Bustad Companion Animal Veterinarian of the Year Award
Recipient, American Animal Hospital Association Animal Welfare and Humane Ethics Award
Recipient, Dog Writers Association of America Award for Best Blog
Recipient, Eukanuba Canine Health Award
Recipient, AKC Club Publication Excellence Award
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Please visit to read excerpts from Speaking for Spot and Your Dog’s Best Health.   There you will also find “Advocacy Aids”- helpful health forms you can download and use for your own dog, and a collection of published articles on advocating for your pet’s health. Speaking for Spot and Your Dog’s Best Health are available at,, local bookstores, and your favorite online book seller.



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6 Comments on “Canine Bladder Infections: Part III

  1. Hi Penny,

    Thanks for sharing your experiences in response to my blog post. Here are a few things to consider. Some dogs normally have crystals without any issues whatsoever. Given that your dog has had crystals in the face of infection makes me more concerned about them. Either now or if you want to wait and see if infection recurs, I strongly encourage an abdominal ultrasound examination (as described in my blog post). X-rays can miss some bladder stones and certainly won’t allow visualization of something like a growth within the bladder. By the way, the fuller your girl’s bladder can be when the ultrasound is performed, the better. I hope this helps.
    Best of luck,

    Dr. Nancy

  2. My spayed female had a stubborn UTI with struvite crystals and a pH of 9. My vet put her on clavamox for two weeks and had me switch her food to Science Diet CD, and put her on “Bladder Support”. After two weeks, it was better, but there were now calcium oxalate crystals instead of struvite. He said to continue the diet and increase the bladder support to twice a day. Two weeks later, she had even more crystals and more signs of infection, so he did an x-ray to rule out bladder stones, and we did a cystocentesis for a culture. I asked about putting her back on the same diet she’d been on for 8 years with no problems, and discontinuing the supplement, which he agreed with. The next day he called me and said that it had already bloomed with a nasty staph infection. Back on Clavamox for two weeks, then another uninalysis, that showed crystal fragments, and a pH of 8. Continued clavamox for two more weeks. Another urinalysis showed still some crystal fragments, but no signs of infection, and a pH of 7, so he told me to just keep an eye on her and that maybe it would just be the norm for her. I then read about switching dogs onto distilled water when they are prone to crystals, so I asked my vet about it and he said it was worth a try. It’s been a little over a week and I’ll have her tested at the end of week two. Your thoughts would be greatly appreciated.

  3. Just a shout-out for the cranberry product Solaray Cran-Actin. It was the first product (and maybe still one of the few/only products) that included an assay of the active compound in the manufacture of each batch. I found it significantly more effective than other products. Also, it is in capsule form so it will not pass through the digestive tract undissolved like some tablets tend to do.

  4. Dr. Kay,

    The first thing I would rule out in a spayed female is an inverted vulva with a thick hymen. No amount of antibiotics work when there is an anatomical issue at hand. Unfortunately, many vets can overlook this condition.

  5. Thank you for this article, and I am glad that you mentioned cranberry extract therapy as a preventative. I had a black lab with Cushing’s Disease who developed bladder infections, and the cranberry extract worked wonders in keeping the infections from recurring. Once the animal has developed an infection I do believe that antibiotics are imperative, but if you know your dog is prone then the cranberry extract can be a great help. After Buster’s last course of antibiotics, I started him on the cranberry extract a few times per week and his infections did not recur. It may not work in every case but it certainly worked for him (works for many people, too!).

  6. Dr. Kay:

    Thank you for these wonderful articles! I wrote after the second part saying that my standard poodle had recovered nicely after a course of antibiotics, but a month later the infection has returned. I have no income to pursue any other treatment and the Banfield Charitable Trust is generous, but not enough for the recommended treatment. He is clearly uncomfortable and we go outside about every two to four hours. At 15 years old, he has done exceptionally well all his life and been very healthy. Your article is very timely and we will do the best we can. Thank you so much!