Cystitis in Dogs

Ultrasound of bladder showing thickened bladder wall which can happen due to various reasons.

Basics

Cystitis means inflammation of the bladder, and the term is used as a general description for any disease that causes inflammation of the bladder.

What Causes Cystitis?

Several diseases and conditions can cause cystitis. The most common cause of cystitis in dogs is a bacterial infection. Other common causes include bladder stones, tumors or polyps in the bladder, and abnormal anatomy (especially in female dogs). Some dogs will experience interstitial or sterile cystitis, a condition that causes inflammation and associated clinical signs without any infection. You may have heard of this type of inflammatory cystitis (interstitial cystitis) in people.

Clinical Signs of Cystitis

The most common clinical sign of cystitis is blood in the urine (hematuria). Cystitis also causes discomfort and pain. Dogs with cystitis may spend several minutes squatting and straining (dysuria) to produce only a small amount of urine, and they may urinate more frequently than normal (pollakiuria). Many pet owners observe their pet squatting frequently and dribbling little spots of urine in multiple locations. Cystitis caused by bacterial infections usually causes hematuria and dysuria.

Bladder Stones and Other Causes

Bladder stones, caused by excessive amounts of crystalline minerals in the urine, frequently form because of bladder infections. The crystals have sharp edges, and the stones can have rough surfaces that cause irritation as they rub against the bladder wall. In severe cases, the bladder stones may block the urethra and obstruct the flow of urine, which is a potentially life-threatening condition.

Tumors or polyps are usually not irritating to the bladder but can cause bleeding and straining to urinate. A urethral diverticulum is an abnormal anatomical defect consisting of a small pouch in the bladder or urethra wall. Bacteria can easily get into this pouch and create an infection that is difficult to treat without surgical removal of the pouch.

Diagnosis of Cystitis

A history of bloody urine, straining to urinate, and urinating more frequently is strong evidence of some form of cystitis. When any or all of these signs are seen, several tests are appropriate. The first group of tests includes urinalysis, urine culture, and bladder palpation (feeling with the fingers).

A urinalysis consists of several tests to detect abnormalities in the urine and urine sediment. These are generally adequate to confirm cystitis, but they may not tell us the exact cause.

Urine culture and sensitivity testing determines if bacteria are present and what antibiotics are likely to be effective in killing them. Bacteria cause most cases of cystitis in dogs and are usually eliminated easily with the appropriate antibiotic.

Bladder palpation is the first diagnostic test for bladder stones, as stones may be large enough to be felt by your veterinarian.

Advanced Diagnostic Testing

If cystitis is present but the culture is negative for bacteria and bladder stones cannot be felt, advanced tests may be required, which include:

Ultrasound examination to evaluate the bladder. This technique uses sound waves to visualize stones as well as tumors and polyps. Ultrasound can identify bladder wall thickening and is often done without sedation or anesthesia.
Bladder X-rays to evaluate the bladder for common types of stones. Some stones require contrast X-rays for detection due to their mineral composition.
Contrast X-rays are a three-step process that allows visualization of stones, tumors, polyps, and wall thickening. This requires sedation or general anesthesia.

If your dog shows other signs of illness, such as increased production of urine, fever, poor appetite, or lethargy, cystitis may be a symptom of a more serious problem. Additional tests like a biochemistry profile, complete blood count (CBC), or clotting profile may be needed.

How Is Cystitis Treated?

Treatment is based on the underlying cause of cystitis:

Bacterial infections are generally treated with antibiotics.
Some bladder stones can be dissolved with special diets, while others require surgical removal (see handout “Bladder Stones in Dogs” for more information).
Benign bladder polyps can usually be surgically removed. Malignant bladder tumors are more difficult to treat successfully.
A bladder diverticulum, which is an anatomical defect, should be surgically removed.

Pain Relief and Supportive Care

In the initial stages of treatment, many cases of cystitis require pain relief or anti-inflammatory medication to relieve discomfort and improve urine outflow. Once the discomfort is relieved, many patients benefit from increased water consumption (either by drinking more or eating a moist diet), which helps flush out bacteria, inflammatory debris, and dissolved crystals from the bladder.

Advanced Conditions and Testing

If your dog shows signs of systemic illness (e.g., increased urination, fever, lethargy), cystitis may be a secondary symptom of a more serious condition such as diabetes mellitus, Cushing's disease, or kidney disease. In such cases, further tests such as a biochemistry profile and complete blood count (CBC) may be necessary to assess organ function.