Canine Urinary Tract Infection
Causes
Bacterial urinary tract infections (UTI) are common in dogs. Infection can
occur at a single site, setting off inflammation in the kidneys (pyelonephritis), ureters (ureteritis),
bladder (cystitis), urethra (urethritis) or the prostate gland (prostatitis); at multiple sites;
or in the urine (bacteriuria). Upper UTIs include pyelonephritis, pyelitis and ureteritis. Lower
UTIs include urethritis and cystitis.
Clinical Signs (Symptoms)
Clinical signs (objective evidence) of UTI include:
- Painful or difficult urination (dysuria)
- Increased frequency of urination (pollakiuria)
- Increased volume of urination (polyuria)
- Excessive thirst (polydipsia)
- Pus in the urine (pyuria)
- Blood in the urine (hematuria)
- Crystals in the urine (crystalluria)
- Lower back (lumbar) pain
Dysuria, frequency, urgency, hematuria or lumbar pain suggests
kidney diseases such as urolithiasis (formation of urinary calculi or mineral salt "pebbles"),
abnormal growth in the bladder (neoplasm), kidney (renal) masses or urinary obstruction. (Urolithiasis
is most common in these breeds: miniature schnauzer, dachshund, Dalmatian, pug, bulldog, Welsh corgi,
basset hound, beagle and terrier.)
Of course, some of these clinical signs are also associated with other diseases, so a veterinarian's
task is to differentiate the specific cause of the dog's clinical condition from other possible causes.
Anatomy of the Canine Urinary Tract
The urinary system eliminates
waste by-products and excess water from the body. Kidneys, which weigh about 1.5 to 2 ounces (42.5 to 56.7 grams),
purify the blood through a filtration process.
The canine urinary tract has upper (proximal) and lower (distal) portions. The upper urinary tract
consists of the kidneys and ureters, tubes that connect the kidneys to the bladder. The lower urinary
tract consists of the bladder and the urethra, which is surrounded by the prostate gland in males.
The urinary tract is normally sterile except for the distal urethra. Pathogens usually invade by
ascending the tract, entering through the urethra and spreading proximally.*
* The Readers Digest Illustrated Book of Dogs, revised edition 1989.
Diagnosing Canine Urinary Tract Infections
Making a differential diagnosis is the process of determining the specific
cause of a dog's urinary tract infection (UTI) in preparation for treatment. A thorough evaluation
should include questions about the dog's history.
- What breed is the dog?
- How old is the dog?
- How often does it urinate?
- How much urine is produced?
- Anything unusual about the appearance or odor of the urine?
- Is the dog excessively thirsty?
- Has the dog broken house-training?
- When were the symptoms first noticed?
- Has the dog been treated for previous urinary tract infections? When and how?
- What has the dog been eating?
Physical Examination
The veterinarian will examine the dog carefully, giving special attention to
the organs of the upper and lower urinary tract.
- The bladder should be felt, or palpated.
- The external genitalia should be examined.
- A rectal examination allows evaluation of the distal urethra in both sexes and of the prostate in male dogs.
- If the dog is unable to control urination (incontinent), a neurologic exam should also be conducted.
Upper UTI often affects kidney function. Special radiographic techniques can
identify renal scarring caused by pyelonephritis, which should be treated differently than other UTI. Renal
calculi act as foreign bodies and perpetuate infection. Magnesium ammonium phosphate calculi also grow as
a result of infection and can injure the kidneys.
Lower UTI is often associated with urinary tract obstruction, urolithiasis and congenital anomalies
of the lower urinary tract and trauma. Although treating lower UTI is important for the animal's
continued health, these infections may have little effect on kidney function.
Treating Canine UTI
For more information on treating canine UTI, visit the following: PRIMOR® (sulfadimethoxine ormetoprim) Tablets, NAXCEL® (ceftiofur sodium) Sterile Powder, and ZENIQUIN® (marbofloxacin) Tablets.
PRIMOR, as with all sulfonamides and potentiated sulfonamides, may be associated with adverse events including polyarthritis, urticaria, facial swelling, fever, hemolytic anemia, polydipsia, polyuria, gastrointestinal signs, seizure and neurological disorders. PRIMOR should not be used in dogs with marked liver damage, blood dyscrasias, or in those with a history of sulfonamide hypersensitivity.
As with all drugs, NAXCEL should not be used in animals found to be hypersensitive to the product.
ZENIQUIN, as with all fluoroquinolones, is not recommended for use in immature dogs during the rapid growth phase, or in dogs known to be hypersensitive to fluoroquinolones. The most common adverse reactions observed during clinical studies were decreased activity, loss of appetite, vomiting and diarrhea.
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