A bacterial infection that leads to inflammation of the bladder is called acute cystitis, which is also known as a bladder infection or urinary tract infection. The urinary tract includes the kidneys, ureters (tubes where urine flows from the kidney to bladder), bladder and urethra (tube that takes the urine from the bladder out of the dog). While the infection is typically in the bladder, any part of the urinary tract could become infected.

Acute cystitis in dogs occurs when there is an inflammation of the urinary bladder, typically due to a bacterial infection.

Should your dog be experiencing acute cystitis, you may notice:

In some cases, no symptoms will be seen.

Types 

Acute cystitis is usually caused by a bacterial infection of the urinary bladder; however, it could also be due to infections of the kidney, ureters or urethra. While much less common, fungi and viruses can also lead to infection of the urinary tract.

The majority of cases of acute cystitis in dogs that are due to bacterial infections are considered ascending, meaning that the cause of the infection came from the intestinal tract of the dog and made its way or ascended to the bladder (or even the kidneys) by way of the anus and urethra, leading to infection. Typically your dog’s defense systems will stop bacteria (or anything else) from making its way up the urinary tract and growing there. When it doesn’t, infection occurs. Acute cystitis is more likely to occur in female dogs than in male dogs.

There are factors that may predispose your dog to experience acute cystitis. These include: 

In order to diagnose acute cystitis, your veterinarian will conduct a physical examination which will include feeling your dog’s abdomen to see about changes in the bladder. He will ask you questions as to your dog’s reproductive status, whether there have been recent changes in your dog’s drinking habits and urination, changes in appetite, and whether he has recently lost weight. You may also be asked about any previous illness and what medications your dog has taken or is currently taking. 

Your veterinarian will conduct tests to confirm that acute cystitis is present, as well as eliminate other possible reasons for your dog’s symptoms. Your veterinarian may collect urine through cystocentesis  or catheterization, in order to conduct a urine test to determine the presence and concentration of leukocytes, white blood cells, erythrocytes, red blood cells and crystals. Your dog’s urine may also be viewed under a microscope for bacteria, though it is important to note that even without bacteria being present, your dog may still have a urinary tract infection. The pH of the urine may be checked as a very high pH or alkaline urine will point to a urinary tract infection.

Typical treatment for acute cystitis (bacterial) includes 2-3 weeks of antibiotics. Sensitivity testing may be recommended by your veterinarian as this will point to the best antibiotics to eliminate the bacteria causing the infection. Your veterinarian may decide to skip sensitivity testing and treat your dog with Penicillin or an antibiotic derived from it as they can attain high concentrations in the urine. It is important that you administer the full course of antibiotics to your dog, even if his symptoms are resolved.

During and after treatment for acute cystitis, your veterinarian may take additional urine samples in order to make sure that the infection has been resolved. It is a good idea to encourage your dog to urinate regularly.

Should your dog have repeated infections, your veterinarian may conduct more tests to understand if there are any conditions that are predisposing your dog to recurrent infections. These tests may include contrast x-rays, ultrasonography, cystoscopy, and additional blood tests. Should any be found, your veterinarian will recommend the appropriate treatment for the underlying condition.

When your dog experiences recurrent infections, your veterinarian may take regular urine samples, for example every 1-3 months, to ensure that the infection has not returned and treat it if it has. Should there be no underlying condition responsible for recurrent infections, your veterinarian may recommend your dog take a low-dose of antibiotics on a long-term basis to prevent recurrent infections.