Your Pet’s Health & Urine

In addition to blood tests, an analysis of the urine is a very
important way for your veterinarian to monitor your pet’s
health. A urinalysis can provide clues to medical problems that
are not apparent in blood tests.

Obtaining a Urine Sample

Please note that when bringing your pet to the veterinarian for
a urinary problem or for a test to evaluate your pet’s urine,
please try to prevent your pet from urinating at home or in the
hospital yard just before bringing it in for its appointment. It
is easier for your veterinarian (and your pet) to have urine in
the bladder when a urine sample is needed or an evaluation of
the bladder must be done. There are several techniques which may
be used to obtain a urine sample from your pet.

Cystocentesis

The best method for obtaining urine samples when testing for
infection is by using a sterile technique to avoid
contamination. This is usually done by a technique called
cystocentesis (tapping the bladder using a small needle and
syringe). This can be done easily and painlessly by placing the
animal on its back or side and by palpating (feeling) the
bladder and by using ultrasound to guide the tap.

Catheterization

Another technique for obtaining a urine sample is by
catheterization by placing a catheter into the urethra. This is
easiest with male dogs which tolerate this procedure well or
with anesthetized male cats. It is rarely done on female dogs
(only for very precisely measuring urine output or for special
contrast studies of the bladder) or almost never on female cats.
When done on male dogs and cats, it is usually done not only to
obtain a urine sample but as a treatment when small crystals or
stones can get lodged in the penis and the animal cannot
urinate. These can be pushed back into the bladder where they
can be more easily removed with surgery or treated medically.

Free catch

A “free catch” technique can be used to obtain a urine sample.
This usually necessitates the owner slipping a clean container
under the pet when s/he urinates. This sample may be used to
check for elements and specific gravity of the urine but cannot
be used to rule out infection.

Urinalysis

There are many tests that may be performed on a urine sample to
provide important information.

Specific gravity

This indicates your pet’s ability to concentrate urine. A low
specific gravity can indicate poor kidney function, some
toxicities and dehydration.

pH

This indicates acidity or alkalinity of the urine. Monitoring
the pH is important in preventing some infections as well as
preventing various crystals and stones from forming in the urine.

Elements

These include: glucose (present with diabetes), ketones (present
with uncontrolled diabetics), bilirubin (present with some forms
of liver disease or anemia), protein (present with some types of
kidney problems).

Sediment

These include: blood (present with infection, inflammation,
tumors, trauma), white blood cells (present with infection),
casts (present with some toxicities and infection) and crystals
(present with certain foods, bladder stones and toxins).

Urine culture and sensitivity

Urinary tract infections (UTI’s) are amongst the most common
medical problems that occur in dogs and cats. While most
affected animals will show signs of straining to urinate, going
small amounts frequently, having accidents in the house, asking
to go out more often or making many trips to the litter box,
many do not show signs (asymptomatic).

Animals especially at risk for UTI’s are those in kidney
failure, those with crystals and/or bladder stones (which harbor
infection) and diabetics (bacteria likes the sugar in the
urine). For these individuals, detecting infection is all the
more important. An untreated UTI can lead to more serious
diseases such as kidney infections (pyelonephritis) or systemic
infections (sepsis).

To detect infection, there are several techniques. Sometimes,
the analysis of the urine itself may reveal the presence of
bacteria and/or white blood cells. However, this test alone will
not find infections in very dilute urine, nor does it tell the
veterinarian what type of bacteria it is and what type of
antibiotic is best to treat it. For this information, it is
necessary to do a urine culture and sensitivity, usually through
an outside laboratory.

Even without any obvious signs of infection, geriatric pets and
all pets with chronic kidney failure should have a urine culture
done every 6-12 months to screen for UTI’s since these pets are
at high risk for infection.

Recommendations for Treatment of UTI’s

One episode of a UTI: These infections can often be treated with
a broad spectrum antibiotic that is most likely to be effective
against common bacteria affecting the urinary tract.

Recurrent UTI’s: A culture and sensitivity is especially
important to determine which bacteria are involved and to which
antibiotic they are most sensitive. Sometimes, the bacteria can
change with each UTI. Ideally, after the initial culture is
done, a follow up culture is done about 5-7 days after stopping
the antibiotics to make sure that all the bacteria has been
eliminated.

If recurrent infections have been in your pet’s history, it is
recommended that urine cultures be done once a month for 3
consecutive months, and every 4-6 months thereafter. Also, it is
important to rule out an underlying cause for these recurrent
infections such as stones or tumors. Xrays and ultrasound are
useful to assess the bladder for these conditions.

UTI’s that are poorly responsive to antibiotic treatment These
animals should have radiographs and/or an ultrasound done to
evaluate their bladders and kidneys for the presence of stones,
crystals, debris, polyps and tumors, all of which can result in
a poor response to antibiotics or recurring infections. After
the initial culture is done, a follow-up urine culture should be
done about 5-7 days into treatment while on antibiotics and
again 5-7 days after stopping a regime of antibiotics (generally
given a minimum of 3 weeks).

Both of these follow-up cultures should be negative. If the
first follow-up culture is positive, the antibiotic should be
changed. If the second one is positive, a urine culture should
be repeated to determine if there is a change in the bacteria or
its sensitivity to antibiotics. A longer course of prescribed
antibiotic treatment is indicated. Occasionally, your
veterinarian may propose an extended course of antibiotic to be
given over several months with urine tests while on the course
of treatment.

Additional Diagnostics: Radiographs and Ultrasound

Radiographs can be used to find some but not all bladder stones.
Not all stones are “radio-opaque”, that is, not all will appear
on a plain radiographs. Sometimes, they can be detected only by
using a special dye study (a contrast cystogram) when dye is
injected into the bladder to highlight the stones. A dye study
is usually needed to see masses of the bladder as well.

Ultrasound is often used to rule out causes of recurrent urinary
problems, and it allows the veterinarian to see inside the
bladder to evaluate for polyps, masses and stones which often
not seen on an xray. Incidental findings of a thickened bladder
wall, polyps, masses, stones or flocculent material (floating
debris) are all reasons for doing a urine culture to rule out an
infection that may be present but not yet causing signs.

Urinary bladder stones

There are several types of bladder and kidney stones. While
kidney stones can occur, bladder stones are more common in
animals. The most common types of stones, based on composition,
are phosphate, urate, cystine and oxalate. Others include:
xanthine, sulfanilamide, carbonate and silica. Mixed stones,
that is, a combination of these types, can occur as well.

Treatment and prevention

Most bladder stones require surgical removal. While stones
originate in the bladder, they sometimes will move down the
urethra and cause straining for female animals and obstruction
for male animals. It is important that the stone be analyzed to
determine its composition so that preventative measures can be
taken since most stones will recur otherwise. This may involve a
diet change and/or medications.

Each stone, depending on its composition, will require a
different treatment regime to change in pH, minimizing certain
elements in food such as magnesium or calcium, increasing urine
production etc. Some stones, especially struvite stones in dogs,
are associated with infection. Depending on their size and the
discomfort experienced by the animal, they may necessitate
surgical removal or they may be amenable to medical treatment.
Only struvite stones can be dissolved with medication and diet
change. However, the infection must be treated as well. Even
after the stones’ surgical removal or dissolution, urine
cultures should follow the same protocol as “recurrent UTI’s”.

If you have questions regarding these tests and the treatment
protocols, don’t hesitate to contact your veterinarian.

The above is general veterinary information. Do not begin
any course of treatment without consulting your regular
veterinarian. All animals should be examined at least once every
12 months.