Dog: Urinary Tract Infection

General information

Other common/scientific names: bladder infection, cystitis, urethritis, UTI, kidney infection, pyelonephritis

The urinary tract consists of the kidneys, ureters (tubes that carry urine from the kidney to the bladder), the urinary bladder and the urethra that carries urine outside the body. A urinary tract infection can be an infection of any of these structures. However, when we speak of a urinary tract infection in dogs, we are usually referring to a bladder infection or cystitis. Infections of the ureters and kidneys, while rare, are more serious conditions.

Abb. GGNHY37T: Schematic illustration of the canine female urinary and reproductive organs.


Bacteria are the most common cause of urinary tract infections. Bacteria normally live around the urethral opening (opening of the urethra where urine exits the body). The dog’s own immune system should prevent these bacteria from entering the urinary tract. When the immune system is compromised or weakened these bacteria can ascend the urethra and cause an infection.

Female dogs are more prone to bladder infections because their urethras are shorter and wider than males. Bacteria have a shorter distance to travel in a female in order to invade the bladder. Female dogs which are spayed are more apt to develop urinary incontinence due to hormonal changes. In these dogs, the bladder sphincter does not function properly and the sphincter allows urine to leak, making these dogs more likely to develop bladder infections. And, dogs with bladder stones or urolithiasis have a higher incidence of bladder infections.

Cardinal symptom

Urge to urinate


A bacterial infection can cause irritation and inflammation to the bladder. This irritation can result in urethral spasms and pain. Because of this, dogs have the urge to urinate but many times produce no urine. So a dog may be seen squatting and straining with a urinary tract infection. Conversely, dogs may be unable to hold their urine and therefore urinate in an inappropriate place such as the house. Other signs of a bladder infection may include hematuria (bloody urine) and increased water consumption. Some dogs with urinary tract infections show no symptoms. On the other hand, if the kidneys are involved, the symptoms can be more severe and include fever, vomiting and lack of appetite.

Abb. GGNHBP4Y: Hematuria (bloody urine).
This is a photograph of a sample of bloody urine from a dog with cystitis.


A presumptive diagnosis can be made from the history and physical examination. A urinalysis is a diagnostic test performed to analyze the urine. This test consists of two parts: the first examines different properties of the urine such as pH, specific gravity (concentration), amount of protein, blood, glucose, ketones and other biochemicals. This is performed by using a special reagent strip dipped in the urine.

Abb. GMRFIPC7: Urinalysis Stick.
This is a photo of the reagent strip used for identifying different properties of urine.

The second part of the urinalysis involves examining the sample under the microscope for abnormal cells, bacteria and crystals. Abnormalities found in the urinalysis can aid in diagnosing a urinary tract infection.

Ideally, a culture and sensitivity is also performed on dogs suspected of having a urinary tract infection. The culture part of this test incubates the urine to determine if bacteria are present. Any bacteria growing in the urine is then identified. The sensitivity part of this test determines which antibiotic(s) is needed to treat the identified bacteria.

Radiographs and ultrasonography are used in cases of recurring cystitis to examine the bladder for chronic thickening, urolithiasis(bladder stones) or bladder cancer.


Most urinary tract infections are treated with antibiotics. These infections need to be treated for 2-4 weeks. If urethral spasms and pain are present antispasmodics and pain medications may be used. Dogs with repeated bladder infections may need to be fed a prescription diet to help control and prevent bladder stones.


Prognosis is good for simple, uncomplicated cases of urinary tract infections. However, if the infection involves bladder stones or the kidneys, successful treatment is more challenging.


Dogs with bladder infections should be encouraged to drink more water and urinate more frequently to help flush the bacteria from the bladder. This can be accomplished by providing plenty of fresh, clean water. If needed, the water can be flavored with broth to enhance drinking. Canned food has more moisture and can also be fed. Dogs should be walked or let outside frequently to increase voiding.

It is important to administer all medications as instructed by your veterinarian. Stopping the antibiotic to soon, even if the dog is showing improvement, can result in recurrence or future bacterial resistance.

Update version: 4/24/2014, © Copyright by
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