About 15% of dogs will have a urinary tract infection (UTI) at some time of their lives. The urinary tract is normally sterile but can get infected. Once a dog has had a urinary tract infection, there may be increased risk of getting another.
Though a dog can get an infection anywhere in the urinary tract; the bladder and urethra account for the vast majority of the infections.
Cystitis is the name for infection of the lining of the bladder.
- How do dogs get urinary tract infections?
- Factors that increase the possibility of a urinary tract infection
- Symptoms of urinary tract infections
- Diagnosis of urinary tract infections
- Treatment of urinary tract infections
- Why do some dogs get repeated urinary tract infections?
The majority of infections start by bacteria getting into the urethra from the outside. Most of the time, the dog’s immune system and the flow of urine will eliminate any bacteria that enter the mouth of the urethra.
Once bacteria have infected the urethra the infection will usually spread up the urethra to the bladder. Therefore, usually a urethral infection will precede a bladder infection.
Sometimes the infection will spread into the ureters and can occasionally get up into one or both kidneys. The longer a bladder infection is left untreated the higher the risk of kidney infection. (See The Dog Urinary System for a diagram and description of the system parts)
Though any dog can get a urinary tract infection there are certain conditions that predispose a dog to getting bladder infections.
- Bladder stones (e.g. struvites)
- Long term steroid use
- Cushing’s disease
- Bladder cancer
- Malformation of the bladder
- Going long periods of time between emptying the bladder
- Old dogs that have trouble completely emptying the bladder
- Prostatitis in non-neutered males
Unfortunately sometimes there may not be any obvious symptoms, at least at the beginning of the infection.
Symptoms can include;
- Frequent urination
- May have “accidents”
- Painful urination
- Urine may be cloudy
- Urine may contain blood
- Urine may have a smell
- Occasionally on close examination may see crystals in urine
- Frequent licking entrance to urethra – more common in females (vulva) than males (penis)
Infection of the urethra and the bladder generally do have other symptoms such as fever. However, if the kidneys have become infected symptoms such as fever, loss of appetite, lethargy or depression will often be present.
First diagnosis is by analysis of the urine. The presence of bacteria shows that there is an infection.
Your vet will also check to see whether there is any evidence of bladder stones in the urine.
If the infection is resistant to treatment or there are multiple urinary tract infections, then your vet will do a chemistry panel, a complete blood count, culture bacteria from the urine for a more complete identification and x-rays, to determine the if other causes such as a weak immune system or bladder stones are part of the problem.
Prompt treatment of a bladder infection is important. The longer treatment is delayed the increased risk of the infection spreading to one or both kidneys. Kidney infections can be difficult to treat.
Your vet will prescribe an antibiotic. The choice of antibiotic will depend on which type of bacteria the vet thinks is causing the infection. Usually a vet will want to start treatment immediately, and not wait for the bacteria to be cultured to confirm the preliminary diagnosis. The course of antibiotic will be for 2 to 3 weeks. Usually the vet will then check the urine to make sure that there are no longer any bacteria in the urine.
Urinary acidifiers may also be suggested. These will help stop bacteria sticking to the walls of the bladder and urethra and help stop the formation of struvites (bladder stones). Common supplements include those made from blackberries, raspberries and cranberries. Your vet may also suggest a special diet until the infection is gone.
- The entire antibiotic treatment not given to the dog
- Bacteria not killed by antibiotic
- Kidney infection
- Another disease such as diabetes
- Immune system suppressed
- Bladder cancer or malformation of the bladder
- Urinary incontinence
- Old dog that can no longer completely empty bladder
- Bladder stones
Despite being told to give the whole course of an antibiotic, it is not uncommon for people to stop before the entire antibiotic is finished. The main reason for this is that a dog is “better” and does not need the rest of the antibiotic.
Often though most of the bacteria are killed there are few bacteria still alive. These bacteria can grow and divide and an infection can build again. Worse some of these bacteria that have survived the antibiotic can become resistant to the antibiotic. The result is that this particular antibiotic will no longer kill these bacteria. Bacterial resistance is becoming a major problem since there are now many types of bacteria that used to killed by a range of antibiotic but now cannot be controlled by these antibiotics.
Always finish a course of antibiotics unless they are making your dog sick. In this case, talk to your vet and often they will give you a different antibiotic. Take the whole course of the new antibiotic to make sure that the bacteria are killed.
The antibiotic may not be appropriate for the type of bacteria, or the bacteria may be resistant (previously sensitive, but has now unaffected by the antibiotic – see section above) to an antibiotic. A vet will use their experience to determine the best antibiotic to use. Since bladder infections can spread to the kidney, most vets will start antibiotic treatment immediately and not wait for the bacteria to be cultured for complete identification. So, occasionally the antibiotic may not be the correct one for the type of bacteria, or alternatively the strain of bacteria may have developed resistance.
As stated above kidney infections can be quite hard to treat. If a dog has a kidney infection, then the kidneys can re-infect the rest of the urinary tract.
Steroids reduce inflammation by suppression the immune system. Therefore, dogs that are on steroids long term are more likely to get repeat urinary tract infections.
When there is bladder cancer or other malformation of the bladder, the inside of the bladder will not be totally smooth, there will be areas where bacteria can “hide”. Also often urine will be trapped in an area and so any bacteria is this residual urine will not be flushed out when the bladder is emptied.
Some old dogs may have neurological problems that make it harder for them to empty their bladder. This incomplete flushing of the bladder increases the risk of bladder infections and makes them harder to treat.
Bladder stones provide a good surface for bacteria to attach and make it harder to completely eliminate an infection. For more information see Why do bladder stones form?
About 15% of dogs will get a urinary tract infection (UTI) at some time in their lives. There may not be any obvious symptoms particularly at the start of the infection. Common symptoms include painful urination, frequent urination, and cloudy and/or bloody urine. Treatment is with antibiotics.
Factors that increase the likelihood of, and recurrence of an infection include bladder stone, diabetes, Cushing’s disease, long term steroid use, bladder cancer and old dogs that cannot completely empty their bladder.