Canine Bladder Infections: Part I

“Rocky” – Photo Credit: Shirley Zindler

If you’ve lived your life with dogs, chances are you’ve cared for one with a bladder infection. The normal urinary bladder is sterile, meaning devoid of bacteria. Infection occurs when bacteria find their way into the bladder and set up housekeeping. Bacterial cystitis (medical-speak for a bladder infection) is a super common diagnosis in the canine world. The term urinary tract infection (UTI) is often used synonymously with bacterial cystitis. Technically speaking, a UTI can mean infection anywhere within the urinary tract, and is not specific to the bladder.

Bacterial cystitis occurs most commonly in female dogs. This is attributed to the fact that compared to males, female dogs have a shorter urethra, the conduit through which urine flows from the bladder to the outside world. With only a short distance to travel in female dogs, bacteria have an easier time migrating from the skin surface up into the urinary bladder. There is no breed predisposition for bladder infections. However, small breed dogs are more susceptible to some of the underlying causes of infection described below.

Causes of infection

While not always easy or even possible to diagnose the cause of infection, there are several underlying issues that make it easier for bacteria to colonize and thrive within the urinary bladder. Anything that disrupts the normal architecture of the urinary tract or reproductive tract (the two are anatomically connected) predisposes to infection. Examples include:

  • Stones within the urinary tract
  • Tumors or polyps within the urinary or reproductive tracts
  • Foreign body within the urinary or reproductive tracts
  • Anatomical birth defects within the urinary or reproductive tracts
  • Prostate gland or testicular disease
  • Vaginal, vulvar, or uterine disease

Urine that is less concentrated (more dilute) than normal creates an environment that is bacteria-friendly. So, it‘s not unusual for bacterial cystitis to accompany diseases associated with increased thirst and increased urine volume, such as kidney failure, liver disease, some hormonal imbalances. Bladder infections occur commonly in dogs with diabetes mellitus, a hormonal imbalance that creates dilute urine. The sugar in the urine of diabetic dogs creates an ideal growth media in which bacterial organisms thrive.

Suppression of the immune system caused by disease or medication promotes bladder infections. Prednisone, a commonly prescribed anti-inflammatory medication, causes urine dilution along with immunosuppression. Not surprisingly, approximately one third of female dogs receiving prednisone develop spontaneous bladder infections.

Symptoms of infection

If ever you’ve experienced a bladder infection you know just how miserable the symptoms can be. Dogs vary a great deal in terms of how dramatically they show evidence of a bladder infection. Some exhibit every symptom in the book while others demonstrate none whatsoever. Additionally, symptoms can arise abruptly or gradually. Every dog reads the textbook a little bit differently!

Symptoms most commonly observed in association with canine bladder infections include:

  • Straining to urinate
  • Urination in inappropriate places
  • Increased frequency of urination
  • Blood within the urine
  • An unusual odor to the urine
  • Urine leakage
  • Increased thirst
  • Excessive licking at the penis or vulva

It is unusual for plain and simple bladder infections to cause lethargy, loss of appetite, or fever. Such “systemic” symptoms, in conjunction with documentation of bacteria within the urinary bladder, create suspicion for infection elsewhere within the urinary or reproductive tracts (kidneys, prostate gland, uterus).

It’s important to remember that dogs are creatures of habit, and any change in habit is a big red flag beckoning you to take notice. Filling the water bowl more than usual? Is your girl squatting more frequently than normal on her morning walks? Is she waking you up in the middle of the night to to go outside to urinate? Has your well house-trained dog begun urinating in the house? All such symptoms are worthy of medical attention. For your dog’s sake, please don’t blame urinary issues on negative behavior before first ruling out an underlying medical issue.

Stay tuned for Canine Bladder Infections: Parts II and III. These articles will discuss diagnostic testing and treatment.

Has your dog ever had a bladder infection? If so, what symptoms did you observe?

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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7 Comments on “Canine Bladder Infections: Part I

  1. On a partially-related note, my rescue Doberman was spayed as an adult dog three years ago when I adopted her, and recently developed a bit of a urine leakage issue.

    After testing it was deemed not to be an infection of any type but, instead, was diminished sphincter control (which apparently isn’t uncommon in spayed adult females).

    My vet indicated there were a couple of prescriptions that could be tried, but she told me not to try ‘doggy diapers’ as that could promote bladder infection.

    Happily, the prescription has worked wonderfully and with no side-effects that we’re aware of.

  2. I justvwentbthrough spending 1200.00 on a bladder infection for my dog! He is 12.5 and started leaking in bed, alot. His urine has
    D a strong odor and he had increased thirst. I took him to a new vet since my vet moved. She said his liver and spleen were huge and she suspected cabcer, she had to do an xray. He was hurt during the xray, he couldnt walk for a week. His spleen and liver were fine. She wanted to get urine sample with needle, she wouldnt culture te urine sample from free catch. Gave antibiotic and charged 900.00!! He wasnt better after 2.5 weeks, took him to another vet who ran culture from free catch and prescribed the right antibiotic. Charged 300.00. The first vet stuck him 6 times to get blood, wish i never took him there, he still has a problem with his leg. This vet said i was a ” red flag” patient because i was. Nervous when they took him in the back for an xray. What a horrible experience!

  3. Hello,
    Almost 2 years ago my 2 year old male German Shepherd developed a UTI. He seemed fine on Saturday and when he got me up during the night I didn’t think much of it at first. He had gotten me up every night and still does, its just him. But when he wanted to go out every hour I was at a loss as to what was going on, especially in my half asleep state. In the dark even with the back yard light on, but without my glasses, I didn’t appreciate the color of the urine. By about 0730 he was not only straining to urinate but his urine was the color of merlot. I took him to the emergency vet and he was diagnosed with a UTI, no prostate enlargement noted. My vet, the breeder and I wracked our brains trying to figure out a cause but came up with nothing, he has not had one since. I just thought you might enjoy a medical mystery that I hope is never repeated.

  4. For Caryn: I don’t know what Dr. Nancy will say about D-Mannose for dogs, but I can tell you, it worked GREAT for me.

  5. I’ve got a 4.5/yr old female Lab who has been generally healthy, but has had frequent UTI infections with eColi in her bladder, bloody urine spotting while sleeping, and she has typically had very diluted urine other than first thing in the AM. We tested her several times for diabetes mellitus (neg) and did a full ultrasound review of the whole system to rule out anything upstream of the bladder (neg), and haven’t found any underlying cause. The last occurrence she was put on Baytril for 6 weeks to be sure we killed any possible hidden infection. Since then I’ve kept her on a daily dose of cranberry concentrate capsules (Pharmaca), which my vet told me would prevent the eColi from binding, and that seems to be working. Fortunately for her, she falls into the camp that doesn’t seem to be bothered by UTI much if at all.

  6. Yes, my previously flawlessly house trained female dog started waking up in puddles on and off during the day. Vet said she “maybe” had struvite crystals and treated with antibiotics. No improvement. It was suggested she wasn’t completely emptying her bladder so I taught her to eliminate on cue so that when I took her outside, she would pee at least twice. No improvement. Another vet suggested “spay incontinence” which I somehow doubted since she’d been spayed at age 2.

    I’m a biologist and I love data so I’d been recording how much she was drinking daily, and what she was eating. At the time I was making home-prepared foods for her (following Pitcairn’s recipes) since we lived in a developing country where it was impossible, at that time, to get high quality, fresh dog food. Looking at the data carefully, I could see it wasn’t every day that Maggie was incontinent.

    Eventually, I narrowed it down to the days I was feeding beef … with a little fresh parsley, added as the green. This was about 10 years ago, when not as much information was available on the internet. So it took a a little googling to reveal that parsley has a diuretic effect. Once I eliminated parsley from Maggie’s diet, no more incontinence.

    The take home lesson for me was to be very careful with herbs and that it is well worth keeping a health and diet journal for your dog. Hope this story helps someone!

  7. I’m looking forward to reading more – my 13 year old neutered male tripawd is having UTIs every 2-3 months and we cannot figure out why. He’s on a homecooked balanced diet through a reputable nutrition consultant, lives in a very clean home, is otherwise healthy and blood work is done every 3 months (spotless!). He never had them until he hit 13 years.

    I know he’s getting one when he sleeps in later than usual, goes to bed earlier, is a little more lethargic and groans when I lift him into his wheelchair/cart. I immediately discontinue the cart and do shorter / more frequent walks (to avoid lifting especially near that area!) and call in the abx. Within 1-2 days he’s perky and acts like a 2 year old again. Once the abx are done, he’s not nearly as happy and perky but he’s not lethargic and pained.

    It’s an interesting system.

    I was debating adding D-Mannose to his daily diet but will keep reading to find out what you have to say too.