Urinalysis
Examination of the urine can give almost as much useful information about
the health of your Beardie as the CBC and Biochemistry profile, and should
be part of each wellness visit to the vet as well as when your dog has
problems relating to urination These can include an increase or decrease
in urination, difficulty urinating, blood in the urine, a foul or unusual
smell to the urine or an odd coloration If you suspect a urinary tract
infection it is best if the vet collects urine directly from the bladder
via a needle inserted through the abdominal wall near the belly button
This is called cystocentesis Urine that passes from the body via the
normal route or via catheter is likely to pick up the bacteria normally
present on the dogs hair or in the prepuce or vulva, or which have been
introduced into the bladder via the catheter However, if the vet
accidentally punctures a blood vessel during cystocentesis there may be
blood in the sample which wasnt present in the urine Urine should be
analyzed within 20 to 30 minutes after it leaves the body, or the
composition will start to change For this reason it is better if the
urine can
be collected at your vets office
Physical Characteristics
Color Normally the urine is yellow to amber becoming darker as the urine is
more concentrated Red urine indicates the presence of blood hematuria
In this case, the urine is usually cloudy and clears when spun in a
centrifuge If the discoloration occurs mostly at the start of urination
it indicates a problem in the urethra or the genital tract, if it occurs
mostly at the end of urination the source is probably the bladder
Other abnormal colorants would include bilirubin - the pigment from bile -
that makes urine dark yellow to brown with a yellow foam Steroids, some
antibiotics and other drugs can increase levels of bilirubin, while
ascorbic acid vitamin C can reduce it Bilirubin levels in urine may
precede the increase in blood causing jaundice Hemoglobin blood pigment
and myoglobin muscle pigment will turn urine a reddish brown
Porphyrins - substances that help form various substances in the body but
especially hemoglobin - give acid urine a pink fluorescence in ultraviolet
light Drugs and vitamins can also alter the color of the urine
Transparency Urine is usually clear when voided, but becomes cloudy if
left
to stand, as the salts precipitate and form crystals Cloudy urine doesnt
necessarily indicate pathology, but should be examined microscopically
Besides crystals, cells, blood, mucus, bacteria, casts and sperm may cause
urine to appear cloudy
Odor Bacterial enzymes called ureases cause ammonia to form in urine, and
the longer it has been retained or allowed to sit the stronger the smell
will be If urine smells of acetone nail polish remover it suggests
ketosis - where the body uses fat rather than glucose for energy Certain
drugs also impart characteristic odors to urine
Volume Volume is usually not measured as part of the urinalysis The 24-
hour production may be measured if the rare condition of diabetes insipidus
where the dog cannot concentrate its urine or psychogenic polydipsia in
which the dog continues to drink in excess of its bodys needs are
suspected If your Beardie seems to pee a lot make note of how much he is
drinking and vice versa This is useful information for your vet
Possible causes of increased urine volume in addition to those mentioned
are acute or chronic kidney disease, diabetes mellitus pancreas doesnt
produce enough insulin, liver failure,
Cushings disease, increased blood
calcium, or pyometra Reduced urine volume is also associated with acute
kidney disease, dehydration, shock, terminal chronic kidney disease or
urinary tract obstruction
Urine Concentration This is usually measured as specific gravity
However, this can vary greatly in normal animals depending on their
hydration status A dog with a specific gravity greater than 1030 is
presumed to be able to concentrate urine adequately If there is a concern
about how well the dog can concentrate urine, the first urine of the day
after being deprived of water overnight is most informative
Chemical Characteristics
Protein The amount of protein present in urine should be evaluated with
regard to the specific gravity The less concentrated the urine the more
significant the presence of protein - proteinuria If there is significant
protein in the urine then the source must be determined Blood can
indicate hemorrhage into the urinary tract, while white cells alone
indicate inflammation of the urinary tract, although not the location of
the problem Very high values of protein - in the absence of blood or
cellular sediment with or without casts - is typically
found in kidney
disease primarily affecting the glomeruli - the parts of the kidney where
blood filtration takes place If the kidney disease affects the tubules
where active and passive exchange of water and electrolytes occurs protein
levels will be low to moderate Most kidney disease affects both glomeruli
and tubules though, and protein levels will be relatively high Transitory
mild increases in proteinuria associated with temporary changes in
glomerular permeability can occur in fever, heart disease, seizures, shock
or muscular exertion Non transient proteinuria is usually divided into
prerenal - hemoglobin, myoglobin and other low molecular weight proteins
can be excreted if their concentration in the blood is high; renal or
postrenal - due to urinary tract infections or hemorrhage Recently,
urinalysis has begun to include measurement of microalbumin in the urine
This is considered elevated if the level is greater than 25 mg/dl This
test is used as an early detection tool for detecting kidney disease before
significant damage to the kidneys has already occurred as it will have when
levels of albumin in the urine are detectable by standard tests
Glucose If blood levels
of glucose exceed the capacity of the tubules to
resorb it, then glucose appears in the urine This usually happens when
blood glucose is greater than 180 mg/dl Problems with the renal tubules
themselves rarely cause a problem, certainly in Beardies Diabetes
mellitus is the primary rule-out for glucosuria
Ketones Ketonuria is present before ketones are detectable in the blood
It indicates the excessive breakdown of fat and/or deficient carbohydrate
metabolism It can result from diabetes mellitus, starvation or low
carbohydrate high fat diets
Bilirubin If bile flow is obstructed bilirubin is released into the blood,
and from there into the urine In dogs it will be detected in urine prior
to detection in the blood This is important as it will allow earlier
detection of gall bladder and/or liver disease However, it is non
specific, and a positive result may also be due to the breakdown of red
cells in the blood vessels or from hemoglobin in the urine
Occult Blood Positive tests indicate blood, hemoglobin or myoglobin in the
urine If it is blood, red cells will be found in the sediment, and some
of these will have broken releasing hemoglobin into the urine It
usually
indicates a problem in the lower urinary or genital tract unless blood is
collected by cystocentesis in which case it is probably an artifact If
hemoglobin is present in the urine it will not clear on centrifugation,
erythrocytes will usually not be present, and plasma will also be reddish
in color It usually indicates an intravascular hemolytic anemia
Myoglobin produces brown rather than red urine, that doesnt clear on
centrifugation, but plasma will be clear There will be no evidence of
anemia Its presence indicates muscle disease
Urobilinogen can only be measured in fresh urine as it degenerates quickly
It is formed in the gut from bilirubin so that it can be resorbed and used
to make more bile acids Its presence in the urine indicates that the bile
duct is not completely blocked Levels vary dramatically though and
absence does not prove the bile duct is blocked Levels increase in
hemolytic diseases and also if there is reduced functional liver mass
pH pH is a measure of the acidity or alkalinity of the urine The healthy
kidneys maintain optimal blood pH by secreting hydrogen or bicarbonate ions
into the urine as necessary It can only be measured in
absolutely fresh
urine as urine loses carbon dioxide if left to stand making it more
alkaline High protein diets make urine more acid Cystitis and other
causes of urine retention make urine more alkaline as urea is converted to
ammonia The pH of the urine determines which types of crystals and
uroliths stones may form Certain drugs can affect urine pH, while urine
pH can affect the efficacy of certain drugs to treat urinary tract disease
Sediment Examination
The quantity of sediment in urine depends on how concentrated it is, so
values must be evaluated taking the urines specific gravity into
consideration The method of collection will also influence the type and
amount of sediment present due to contamination outside the urinary system,
or bleeding during cystocentesis
Epithelial cells are of three types Squamous epithelial cells slough off
from the urethra, vagina and prepuce and are of no diagnostic significance
Transitional epithelial cells come from the upper urethra, bladder,
ureters and the pelvis of the kidney - the part where the filtered urine
collects before passing via the ureters to the bladder They are only of
diagnostic significance in cases of
transitional cell cancers Renal
epithelial cells come from the kidney tubules and are often hard to
distinguish from the slightly smaller white cells
Red Blood Cells More than 4 or 5 RBCs erythrocytes per high power field
indicates hemorrhage due either to trauma or inflammation of the urinary
tract In concentrated urine they can have an irregular outline, and in
dilute urine they may lyse Certain yeasts can also resemble RBCs
White Blood Cells More than 5 to 8 WBCs leukocytes per high power field
indicates pus in the urine that may or may not be septic They are usually
seen with bacteria in the urine, but bacteria can occur without pus WBCs
break down as urine is left to stand, and also in dilute and alkaline
urine
Casts These elongated structures form on a skeleton of mucoprotein produced
in the distal tubules of the kidneys when the urine is acidic - alkaline
urine tends to dissolve them Anything present in the distal tubules at
the time of formation will be embedded in the cast While they indicate
changes in the tubules, they can be seen in healthy individuals, and do not
measure the severity of kidney disease They are discharged
intermittently, so their absence also
does not rule out kidney disease
Hyaline casts are hard to detect, and are composed solely of mucoprotein
Granular casts are the most common type and contain plasma proteins and any
tubular debris They are similar to epithelial casts, although these also
contain epithelial cells sloughed from the lining of the tubules Waxy
casts lack granular content and are wide and often have broken ends They
are degenerating cellular or granular casts and indicate chronic tubular
damage Fatty casts contain globules of fat from degenerating tubular
epithelial cells Erythrocyte casts indicate hemorrhage or inflammation in
the kidneys and leukocyte casts kidney inflammation
Mucus indicates irritation of the urethra, or genital secretion Fat may
be seen and is of no pathological significance Sperm may also be present
Bacteria These can be divided into rods longer in one dimension or cocci
basically round and can occur singly or in chains They are best
identified using stains As a general rule, there must be 30,000
bacteria/ml present before they can be visualized microscopically Urine
is sterile only until mid urethra, so bacteria seen on free catch or
catheterized urine specimens are
of questionable diagnostic significance
While it may be acceptable veterinary medicine to prescribe antibiotics
which are generally efficacious to dogs with a first or rare urinary tract
infection, culture and sensitivity to antibiotics in vitro must be
determined for dogs with recurrent or persistent infections and the urine
must be obtained via cystocentesis to avoid contamination
Parasites Those parasitic structures that may be seen in urine include
Diotophyma renale - the giant kidney worm, which dogs can get from
ingesting infected raw fish or frogs; Capillaria plica eggs - dog bladder
worm, dogs become infected by eating infected earthworms; microfilaria of
Dirofilaria immitis, the dog heartworm While budding yeasts and segmented
hyphae may be seen in urine, fungi are purely contaminant artifacts
Crystals Precipitation will depend upon the pH of the urine and the
solubility and concentration of the crystalloid Crystals are identified
by their shape, color and whether they dissolve in acids or alkaline
solutions Only when crystals become large enough to form stones or
uroliths do they usually have clinical significance The following
crystals may indicate potential
pathology
Ammonium biurate can occur with portal venous systemic shunts and other
liver diseases
Tyrosine may be associated with liver disease
Cystine is caused by altered protein metabolism, usually congenital
cystinuria - seen most often in Chihuahua, Dalmatians, Dachshunds, Tibetan
spaniels, Landseer Newfoundlands, bulldogs, and basset hounds
Sulfonamide These crystals are seen in dogs that have been treated
excessively with sulfa antibiotics
Oxalates These may be normal, but are also seen in dogs with ethylene
glycol antifreeze and certain plant toxicities
Hippuric acid These may also occur with ethylene glycol ingestion
Struvite or triple phosphate These crystals form in alkaline urine While
struvite calculi are the most common type of urinary stone, crystals are
usually present without stones
Uroliths
The formation of stones in the urinary tract is not usually diagnosed by
urinalysis However, they usually present with straining to urinate, blood
in the urine prompting the owner to bring the dog for urinalysis, others
may be found on routine health check having no presenting signs
Calcium Oxalate These are found most often in miniature schnauzers, Lhasa
apsos and
Yorkshire terriers Risk factors include excessive dietary
calcium, protein, sodium and vitamin D all of which produce increased
calcium in the urine Dietary oxalates found in chocolate and peanuts as
well as ascorbic acid increase oxalate secretion High concentrations of
glucocorticoids whether natural or given as drugs and the diuretic
furosemide also increase calcium excretion Crystals of calcium oxalate
may be seen in the urine sediment Special diets do not dissolve these
stones They can either be flushed back into the bladder and removed
surgically or broken up with shock wave lithotripsy Even if blood calcium
remains normal, most affected dogs form new stones within three years
Calcium Phosphate These are also called apatite stones They form more
often in the kidneys than in the bladder Pure apatite stones are usually
associated with primary hyperparathyroidism kidney tubular acidosis or
excessive dietary calcium and phosphorus However, some apatite is usually
found in both struvite and calcium oxalate stones Crystals of some forms
of calcium phosphate may be seen on urinalysis Primary diseases must be
treated, but surgery or lithotripsy may be needed to remove
obstructive
stones Canned diets that reduce calcium excretion and restrict phosphorus
are used to prevent further stones forming too
Cystine Cystine, a non-essential amino acid, is normally present in low
concentrations in plasma and having been filtered out by the glomeruli is
resorbed by the proximal tubules of the kidneys In dogs with cystinuria
not only is the cystine not resorbed it may be actively secreted Cystine
dissolves in alkaline urine but forms crystals and stones in acid urine
Not all dogs with cystinuria form stones Stones can be dissolved by
adding 2-mercaptopropionyl glycine 2-MPG which compounds with cystine in
a more soluble form Urine alkalinizers and diets which reduce urinary
excretion of cystine while diluting urine concentration are used to manage
these uroliths
Struvite These uroliths are composed of magnesium ammonium phosphate
hexahydrate MAP aka struvite The formation of these stones requires
supersaturation of the urine with MAP and it is usually associated with
urinary tract infections caused by urease producing bacteria - especially
Staphylococcus, Proteus and Ureaplasma Urine has to be alkaline
Elevated urea in the urine from high protein
diets or the breakdown of
amino acids for other reasons also contributes to MAP formation Anatomic
and metabolic abnormalities that predispose dogs to urinary tract
infections are another risk factor While any breed may be affected
miniature schnauzers, dachshunds, poodles, Scottish terriers, beagles,
Pekingese, and corgis are at particular risk Struvite stones can be
dissolved using a special calculolytic diet This is to be used only for
the time it takes to dissolve the stones and should not be used long term
It must also not be used in a dog that requires more protein than is
present in the diet Any UTI should be treated with appropriate
antibiotics Urinary acidifiers and diligence in early detection and
treatment of urinary tract infections will help prevent recurrence
Urate Uric acid, sodium urate or ammonium urate uroliths occur in dogs
with impaired metabolism or uric acid and ammonia, they are frequently seen
in dogs with portosystemic shunts Dalmatians, bulldogs, miniature
schnauzers and Yorkshire terriers are at the greatest risk Urine is acid
and urate crystals will be seen Crystals can be dissolved by feeding a
low purine, urine alkalinizing diet Initially,
urinalysis should be
repeated every one to two months to detect recurrence as early as possible
If urate crystals are not detected this can increase to every 2-4 months
if the dog is clear for 6 months
Xanthine These uroliths occur if the dog is receiving allopurinol used to
treat uric acid uroliths as well as Leishmania and trypanosomiasis and
fails to convert xanthine to uric acid Some cases are congenital
Xanthine crystals are distinctive and can be seen in urine sediment
Stones must be removed surgically Allopurinol should be discontinued and
the dog put on a low purine diet
For a substance that we consider a waste product and rather unpleasant
urine can certainly give us a lot of information about the health of our
dogs With luck everything will be normal on your Beardies urinalysis, if
not I hope the above overview will help you understand any problems there
may be so that you can better discuss your Beardies health with your
veterinarian
Linda Aronson, DVM
Source:beaconforhealth.org
