Canine Urolithiasis
Urolithiasis is a disease caused by the presence and effects of
uroliths (stones) or calculi or excessive amounts of crystals in
the urinary tract. The disease is referred to by many names,
including cystitis, urethritis, urinary calculi, bladder stones,
or kidney stones. As in humans, these stones and crystals can
form anywhere in the urinary tract of the dog, including the
kidney, urethra, or most commonly, the bladder. These crystals
or stones irritate the lining of the urinary tract, causing
changes in the lining, blood in the urine, and often pain. In
some cases the crystals or stones will block or partially block
the flow of urine, making urination painful or impossible.
Signs of Canine Urolithiasis
A dog with urolithiasis will exhibit some or all of the
following symptoms: frequent urination (often in unusual
places), bloody urine, dribbling urine, straining, weakness,
depression, loss of appetite, vomiting and pain. If your pet has
any of these symptoms, you should contact your veterinarian
immediately. In some cases without appropriate diagnosis and
treatment, your dog could face a life threatening situation.
Stones can block the urine flow, prevent elimination of
poisonous wastes and cause death. It is important to know that
not every dog with canine urolithiasis exhibits all of these
symptoms.
Definition of Terms
Your veterinarian may use some terms in describing urolithiasis
with which you are not familiar. These terms include cystitis,
crystaluria, urolith, and urethral obstructions.
Cystitis is an inflammation of the urinary bladder. This
condition occurs because of a bacterial or possibly a viral
infection which results from the irritation caused by crystals
and stones in the bladder. Cystitis may contribute to the
formation of additional stones within the bladder.
Crystaluria denotes the presence of crystals in the urine.
Crystals form when minerals bind together. The bound crystals
are not as soluble as the unbound form and may result in mineral
deposits, much like the deposits commonly found in a teapot or
coffee maker.
When more and more of these crystals join together, they form a
urinary stone or urolith. There are several different types of
stones and each should be treated or prevented differently. It
is important for your veterinarian to know what type of stone
your dog has.
Urethral obstruction occurs when stones or an accumulation of
crystals partially or completely block the tube through which
urine is excreted. This is very painful and is a medical
emergency.
Important Factors
There is no single cause of canine urolithiasis. Yet, there are
a number of important factors. They are:
Age: Urolithiasis may appear in your dog when it is less than
two months old, but most stones occur in dogs two to ten years
of age.
Sex: Urolithiasis appears to occur with equal frequency in
adults of both sexes. However, because the urethra of the male
is longer and narrower than the female's, urethral obstruction
is more common in males.
Breed: Small breeds, including the Welsh Corgi, Miniature
Schnauzer, Pug, Lhasa Apso, Pekingese and Yorkshire Terrier are
more commonly affected than are large breeds. The Beagle,
Dachshund, Dalmatian, Bulldog, Basset Hounds, Cairn Terrier and
Scottish Terrier are also susceptible.
Confinement and Exercise: Infrequent urination, as a result of
confinement, lack of regular exercise, or low water intake,
contribute to the formation of crystals and uroliths.
Diet: High levels of some minerals in the diet, such as
magnesium, phosphorus, and sometimes calcium, have been directly
linked to canine urinary bladder stone formation. A diet with
excess protein can also contribute to stone formation.
In most cases, stones are made up of only one type of crystal,
but on occasion, different crystals may be mixed within the same
stone. Each type of stone is affected by different nutrients and
characteristics of the diet. Therefore, it is important to know
what type of stone your dog has.
Diagnosis of Canine Urolithiasis
If your veterinarian suspects your dog may have uroliths, he or
she may perform some or all of these diagnostic tests: abdominal
palpation, to feel stones present in the urinary bladder;
urinalysis, to determine the types of crystals present; urine
culture with antibiotic sensitivity, to determine if bacteria
are present in the urinary tract and the appropriate antibiotic
with which to treat these bacteria; and radiographic examination
(possibly with contrast media), to see if stones are present and
their location in the urinary tract. To evaluate how well your
pet is responding to therapy, your veterinarian may periodically
repeat some of these tests. Therefore, you will need to bring
your pet in for rechecks as directed by your veterinarian.
Treatment/Management
If the urinary tract is blocked, your veterinarian will have to
correct the blockage and empty the dog's urinary bladder. Then,
your dog will be further examined to determine the stone type
and appropriate therapy. Your pet may need to stay at the
hospital during this process. In the past, urinary bladder
stones have been surgically removed and for some stones, surgery
may be the only effective treatment. But for most stones, there
is an alternative.
In most cases, stones may be dissolved by feeding a special diet
with reduced amounts of certain minerals and protein, or a
special diet plus medication. If an infection is present,
antibiotics are also necessary. Special diets work by reducing
the mineral building blocks or urinary stones in the urine.
These diets affect the urine pH and increase urination to help
flush the urinary tract.
If your veterinarian recommends dissolving the stones by feeding
a Prescription Diet