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Bladder stone (animal)
Encyclopedia
Bladder stones or uroliths are a common occurrence in animals, especially in domestic animals such as dog
s and cat
s. Occurrence in other species, including tortoise
s, have been reported as well. The stones form in the urinary bladder
in varying size and numbers secondary to infection
, dietary influences, and genetics
. Stones can form in any part of the urinary tract in dogs and cats, but unlike in humans, stones of the kidney
are less common and do not often cause significant disease, although they can contribute to pyelonephritis
and chronic renal failure
. Types of stones include struvite
, calcium oxalate
, urate
, cystine
, calcium phosphate
, and silicate
. Struvite and calcium oxalate stones are by far the most common.
with crystals is by the far the biggest factor in stone formation. This oversaturation can be caused by increased excretion of crystals by the kidneys, water reabsorption by the renal tubules resulting in concentration of the urine, and changes in urine pH
that influence crystallization. Other contributing factors include diet, frequency of urination, genetics, current medications, and the presence of a urinary tract infection
.
The stones form around a nidus
, which can consist of white blood cell
s, bacteria
, and organic matrix mixed with crystals, or crystals alone. The nidus makes up about two to ten percent of the mass of the stone. It is possible for the nidus to be made of a different type of crystal than the rest of the stone, also known as epitaxial growth
.
) (giving the appearance that the animal is urinating blood) but sometimes there may be no signs at all. Painful urination or straining to urinate are other signs. Urinary tract infections are commonly associated with bladder stones. Smaller stones may become lodged in the urethra
, especially in male animals, causing urinary tract obstruction
and the inability to urinate. This condition causes acute renal failure
, hyperkalemia
, septicemia, and death within a few days.
. Most types of stones will appear readily in an x-ray, urate and occasionally cystine stones being the most common exceptions. Stones smaller than three millimeters may not be visible. Ultrasonography is also useful for identifying bladder stones. Crystals identified in a urinalysis
may help identify the stones, but analysis of the stones is necessary for identification of the complete chemical composition.
is necessary. In male dogs with recurrent urinary tract obstruction a scrotal urethrostomy creates a permanent opening in the urethra proximal to the area where most stones lodge, behind the os penis. In male cats, stones lodge where the urethra narrows in the penis. Recurrent cases can be treated surgically with a perineal urethrostomy, which removes the penis and creates a new opening for the urethra.
To prevent recurrence of stones, special diets can be used for each type of stone. Increasing water consumption by the animal dilutes the urine, which prevents oversaturation of the urine with crystals.
Struvite
stones are also known as magnesium ammonium phosphate stones due to their chemical composition - MgNH4PO4·6H20. Often there is a small amount of calcium phosphate present. They form at a neutral to alkaline pH of the urine. Bacterial infections contribute to their formation by increasing the pH of the urine through the urease
enzyme in dogs. More than 90 percent of dogs with struvite stones have an associated urease-producing bacterial infection in the urinary tract, but in cats struvite stones usually form in sterile urine. The appearance of the stones vary from large solitary stones to multiple smaller stones. They can assume the shape of the bladder or urethra.
Dissolution of the struvite stones depends on acidification of the urine through diet or urinary acidifier
s. Special diets for dissolution also have reduced protein
, phosphorus
, and magnesium
, as well as increased salt to increase water consumption and dilute the urine. The diet needs to be fed exclusively, but it can only be fed for a few months total due to potential side effects. Contraindication
s to this diet include heart failure, liver failure
, kidney failure, pancreatitis
, hypertension
(high blood pressure), and hypoalbuminemia
(low serum albumin
). Prevention of struvite stones is with a similar diet with milder restrictions.
Certain dog breeds are predisposed to struvite stones, including Miniature Schnauzer
s, Bichon Frise
s, and Cocker Spaniels. They are the most commonly reported bladder stone in female dogs and in ferret
s (pregnant ferrets may be especially predisposed). For frequency in cats, see below.
Calcium oxalate
stones form in an acidic to neutral urine. Two types naturally occur, calcium oxalate monohydrate, or whewellite
(CaC2O4·H2O), and calcium oxalate dihydrate, or weddellite
(CaC2O4·2H2O). Their appearance can be rough, smooth, spiculated
, or jacks
tone. Calcium oxalate stones form more readily in animals with hypercalcaemia
, which can caused by Addison's disease
or certain types of cancer
. Hypercalcaemia results in hypercalciuria
, which can also be caused by Cushing's syndrome
or hyperparathyroidism
.
There is no recommended diet to dissolve calcium oxalate stones. For prevention a diet low in protein and oxalate
s and high in magnesium, phosphorus, and calcium is recommended. Increased dietary magnesium and phosphorus decreases the amount of calcium in the urine, and increased dietary calcium reduces absorption of oxalates from the intestines. Potassium citrate
has been recommended as a preventative for calcium oxalate stone formation because it forms a soluble complex with oxalates and promotes the formation of alkaline urine.
Dog breeds possible prone to calcium oxalate stones include Miniature Schnauzer
s, Lhasa Apso
s, Yorkshire Terrier
s, Miniature Poodles, Shih Tzu
s, and Bichon Frise
s. They are the most common stone in male dogs. Calcium oxalate stones are also common in domestic rabbit
s. Rabbits are prone to hypercalciuria due to intestinal absorption of calcium not being dependent on vitamin D
and a high fractional urinary excretion of calcium. The urine will appear thick and creamy or sometimes sandy. Small stones and sand can be removed using urohydropropulsion. Prevention is through reducing calcium intake by feeding more hay and less commercial rabbit pellets, and by not using mineral supplements.
College of Veterinary Medicine has done detailed analysis of uroliths from animals since 1981 and has noted changing trends in feline uroliths. In 1981, struvite stones were the most common type in cats, making up 78 percent of submitted samples, with only 2 percent comprising calcium oxalate stones. In the mid 1980s there was a substantial increase in the number of calcium oxalate samples, and between 1994 and 2002, 55 percent of feline stones were calcium oxalate and 33 percent were struvite. This may have been caused by the use of dissolution diets for struvite stones in cats and modification of other diets to prevent struvite crystal formation. These modifications predisposed to calcium oxalate crystal formation. However in 2004, struvite stones once again surpassed calcium oxalate stones 44.9 percent to 44.3 percent, and in 2006, 50 percent of stones were struvite and 39 percent were calcium oxalate. This may have been due to the increased use of diets designed to prevent calcium oxalate crystal formation, which because of increased magnesium in the diet and decreased acidity of the urine help promote struvite crystal formation.
Urethra
l plugs in cats are usually composed of struvite crystals and organic matter.
Urate (C5H4N4O3) stones, usually ammonium urate (NH4·C5H4N4O3) or sodium urate monohydrate (Na·C5H4N4O3×H2O), form in an acidic to neutral urine. They are usually small, yellow-brown, smooth stones. Urate stones form due to an increased excretion of uric acid
in the urine. Dalmatian
s (especially males) and to a lesser extent Bulldog
s are genetically predisposed to the formation of urate stones because of an altered metabolism of purine
s. Dalmatians have a decreased rate of urate hepatic transport, leading to only about 30 to 40 percent conversion of urate to allantoin
, compared with greater than 90 percent conversion in other breeds. Dogs with portosystemic shunt
s or endstage liver disease also have increased uric acid excretion in the urine due to reduced conversion of uric acid to allantoin
and ammonia
to urea
. Urate stones make up about six percent of all stones in the cat.
Urate stones can be dissolved using a diet with reduced purines that alkalinizes and dilutes the urine. Allopurinol
is used in dogs with altered purine metabolism to prevent the formation of uric acid. Feeding a diet high in purines while simultaneously administering allopurinol can result in the formation of xanthine
(C5H4N4O2) stones.
((SCH2CHNH2COOH)2) stones form in an acidic to neutral urine. They are usually smooth and round. They are caused by increased urine excretion of cystine (a relatively insoluble amino acid) in dogs with a defect in renal tubule reabsorption of cystine. Dietary reduction of protein and alkalinization of the urine may help prevent formation. Medications such as D-penicillamine and 2-MPG contain thiol
, which forms a soluble complex with cystine in the urine. Dog breeds possibly predisposed to formation of cystine stones include Bulldogs, Dachshund
s, Basset Hound
s, Chihuahua
s, Yorkshire Terriers, Irish Terrier
s, and Newfoundland
s. In Newfoundlands, cystinuria is inherited as an autosomal recessive trait, but in the other breeds it is a sex linked
trait and found primarily in male dogs.
, also known as hydroxyapatite (Ca10(PO4)6(OH)2), stones form in neutral to alkaline urine. They are usually smooth and round. Calcium phosphate is usually a component of struvite or calcium oxalate stones and is infrequently a pure stone. They form more readily with hypercalcaemia. Dog breeds possibly predisposed to calcium phosphate stone formation include Yorkshire Terriers, Miniature Schnauzers, and Cocker Spaniels.
(SiO2) stones form in acidic to neutral urine. They are usually jackstone
in appearance. There is possibly an increased incidence associated with dogs on diets that have a large amount of corn gluten
or soybean
hulls. Dog breeds possibly predisposed include German Shepherd Dog
s, Golden Retriever
s , Labrador Retriever
s, and Miniature Schnauzers.
Dog
The domestic dog is a domesticated form of the gray wolf, a member of the Canidae family of the order Carnivora. The term is used for both feral and pet varieties. The dog may have been the first animal to be domesticated, and has been the most widely kept working, hunting, and companion animal in...
s and cat
Cat
The cat , also known as the domestic cat or housecat to distinguish it from other felids and felines, is a small, usually furry, domesticated, carnivorous mammal that is valued by humans for its companionship and for its ability to hunt vermin and household pests...
s. Occurrence in other species, including tortoise
Tortoise
Tortoises are a family of land-dwelling reptiles of the order of turtles . Like their marine cousins, the sea turtles, tortoises are shielded from predators by a shell. The top part of the shell is the carapace, the underside is the plastron, and the two are connected by the bridge. The tortoise...
s, have been reported as well. The stones form in the urinary bladder
Urinary bladder
The urinary bladder is the organ that collects urine excreted by the kidneys before disposal by urination. A hollow muscular, and distensible organ, the bladder sits on the pelvic floor...
in varying size and numbers secondary to infection
Urinary tract infection
A urinary tract infection is a bacterial infection that affects any part of the urinary tract. Symptoms include frequent feeling and/or need to urinate, pain during urination, and cloudy urine. The main causal agent is Escherichia coli...
, dietary influences, and genetics
Genetics
Genetics , a discipline of biology, is the science of genes, heredity, and variation in living organisms....
. Stones can form in any part of the urinary tract in dogs and cats, but unlike in humans, stones of the kidney
Kidney
The kidneys, organs with several functions, serve essential regulatory roles in most animals, including vertebrates and some invertebrates. They are essential in the urinary system and also serve homeostatic functions such as the regulation of electrolytes, maintenance of acid–base balance, and...
are less common and do not often cause significant disease, although they can contribute to pyelonephritis
Pyelonephritis
Pyelonephritis is an ascending urinary tract infection that has reached the pyelum or pelvis of the kidney. It is a form of nephritis that is also referred to as pyelitis...
and chronic renal failure
Chronic renal failure
Chronic kidney disease , also known as chronic renal disease, is a progressive loss in renal function over a period of months or years. The symptoms of worsening kidney function are unspecific, and might include feeling generally unwell and experiencing a reduced appetite...
. Types of stones include struvite
Struvite
Struvite is a phosphate mineral with formula: NH4MgPO4·6H2O. Struvite crystallizes in the orthorhombic system as white to yellowish or brownish-white pyramidal crystals or in platey mica-like forms. It is a soft mineral with Mohs hardness of 1.5 to 2 and has a low specific gravity of 1.7...
, calcium oxalate
Calcium oxalate
Calcium oxalate is a chemical compound that forms needle-shaped crystals, known in plants as raphides. A major constituent of human kidney stones, the chemical is also found in beerstone, a scale that forms on containers used in breweries...
, urate
Uric acid
Uric acid is a heterocyclic compound of carbon, nitrogen, oxygen, and hydrogen with the formula C5H4N4O3. It forms ions and salts known as urates and acid urates such as ammonium acid urate. Uric acid is created when the body breaks down purine nucleotides. High blood concentrations of uric acid...
, cystine
Cystine
Cystine is a dimeric amino acid formed by the oxidation of two cysteine residues that covalently link to make a disulfide bond. This organosulfur compound has the formula 2. It is a white solid, and melts at 247-249 °C...
, calcium phosphate
Calcium phosphate
Calcium phosphate is the name given to a family of minerals containing calcium ions together with orthophosphates , metaphosphates or pyrophosphates and occasionally hydrogen or hydroxide ions ....
, and silicate
Silicate
A silicate is a compound containing a silicon bearing anion. The great majority of silicates are oxides, but hexafluorosilicate and other anions are also included. This article focuses mainly on the Si-O anions. Silicates comprise the majority of the earth's crust, as well as the other...
. Struvite and calcium oxalate stones are by far the most common.
Formation of bladder stones
Oversaturation of urineUrine
Urine is a typically sterile liquid by-product of the body that is secreted by the kidneys through a process called urination and excreted through the urethra. Cellular metabolism generates numerous by-products, many rich in nitrogen, that require elimination from the bloodstream...
with crystals is by the far the biggest factor in stone formation. This oversaturation can be caused by increased excretion of crystals by the kidneys, water reabsorption by the renal tubules resulting in concentration of the urine, and changes in urine pH
PH
In chemistry, pH is a measure of the acidity or basicity of an aqueous solution. Pure water is said to be neutral, with a pH close to 7.0 at . Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline...
that influence crystallization. Other contributing factors include diet, frequency of urination, genetics, current medications, and the presence of a urinary tract infection
Urinary tract infection
A urinary tract infection is a bacterial infection that affects any part of the urinary tract. Symptoms include frequent feeling and/or need to urinate, pain during urination, and cloudy urine. The main causal agent is Escherichia coli...
.
The stones form around a nidus
Enterolith
An enterolith is a mineral concretion or calculus formed anywhere in the gastrointestinal system. Enteroliths are uncommon and usually incidental findings but, once found, they require at a minimum watchful waiting...
, which can consist of white blood cell
White blood cell
White blood cells, or leukocytes , are cells of the immune system involved in defending the body against both infectious disease and foreign materials. Five different and diverse types of leukocytes exist, but they are all produced and derived from a multipotent cell in the bone marrow known as a...
s, bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
, and organic matrix mixed with crystals, or crystals alone. The nidus makes up about two to ten percent of the mass of the stone. It is possible for the nidus to be made of a different type of crystal than the rest of the stone, also known as epitaxial growth
Epitaxy
Epitaxy refers to the deposition of a crystalline overlayer on a crystalline substrate, where the overlayer is in registry with the substrate. In other words, there must be one or more preferred orientations of the overlayer with respect to the substrate for this to be termed epitaxial growth. The...
.
Symptoms
Bladder stones may cause blood in the urine (hematuriaHematuria
In medicine, hematuria, or haematuria, is the presence of red blood cells in the urine. It may be idiopathic and/or benign, or it can be a sign that there is a kidney stone or a tumor in the urinary tract , ranging from trivial to lethal...
) (giving the appearance that the animal is urinating blood) but sometimes there may be no signs at all. Painful urination or straining to urinate are other signs. Urinary tract infections are commonly associated with bladder stones. Smaller stones may become lodged in the urethra
Urethra
In anatomy, the urethra is a tube that connects the urinary bladder to the genitals for the removal of fluids out of the body. In males, the urethra travels through the penis, and carries semen as well as urine...
, especially in male animals, causing urinary tract obstruction
Urinary retention
Urinary retention, also known as ischuria, is a lack of ability to urinate. It is a common complication of benign prostatic hyperplasia , although it can also be caused by nerve dysfunction, constipation, infection, or medications...
and the inability to urinate. This condition causes acute renal failure
Acute renal failure
Acute kidney injury , previously called acute renal failure , is a rapid loss of kidney function. Its causes are numerous and include low blood volume from any cause, exposure to substances harmful to the kidney, and obstruction of the urinary tract...
, hyperkalemia
Hyperkalemia
Hyperkalemia refers to the condition in which the concentration of the electrolyte potassium in the blood is elevated...
, septicemia, and death within a few days.
Diagnosis
When symptoms indicate bladder stones, the first step is usually to take an x-rayX-ray
X-radiation is a form of electromagnetic radiation. X-rays have a wavelength in the range of 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz and energies in the range 120 eV to 120 keV. They are shorter in wavelength than UV rays and longer than gamma...
. Most types of stones will appear readily in an x-ray, urate and occasionally cystine stones being the most common exceptions. Stones smaller than three millimeters may not be visible. Ultrasonography is also useful for identifying bladder stones. Crystals identified in a urinalysis
Urinalysis
A urinalysis , also known as Routine and Microscopy , is an array of tests performed on urine, and one of the most common methods of medical diagnosis...
may help identify the stones, but analysis of the stones is necessary for identification of the complete chemical composition.
Treatment
Reasons for treatment of bladder stones include recurring symptoms and risk of urinary tract obstruction. Some stones can be dissolved using dietary modifications and/or medications. Small stones in female dogs may possibly be removed by urohydropropulsion, a nonsurgical procedure. Urohydropropulsion is performed under sedation by filling the bladder with saline through a catheter, holding the dog vertically, and squeezing the bladder to expel the stones through the urethra. Bladder stones can be removed surgically by a cystotomy, opening of the bladder. Stones lodged in the urethra can often be flushed into the bladder and removed, but sometimes a urethrotomyUrethrotomy
A urethrotomy is an operation which involves incision of the urethra, especially for relief of a stricture. It is most often performed in the outpatient setting, with the patient being discharged from the hospital or surgery center within six hours from the procedure's inception.Urethrotomy is a...
is necessary. In male dogs with recurrent urinary tract obstruction a scrotal urethrostomy creates a permanent opening in the urethra proximal to the area where most stones lodge, behind the os penis. In male cats, stones lodge where the urethra narrows in the penis. Recurrent cases can be treated surgically with a perineal urethrostomy, which removes the penis and creates a new opening for the urethra.
To prevent recurrence of stones, special diets can be used for each type of stone. Increasing water consumption by the animal dilutes the urine, which prevents oversaturation of the urine with crystals.
Struvite stones
Struvite
Struvite is a phosphate mineral with formula: NH4MgPO4·6H2O. Struvite crystallizes in the orthorhombic system as white to yellowish or brownish-white pyramidal crystals or in platey mica-like forms. It is a soft mineral with Mohs hardness of 1.5 to 2 and has a low specific gravity of 1.7...
stones are also known as magnesium ammonium phosphate stones due to their chemical composition - MgNH4PO4·6H20. Often there is a small amount of calcium phosphate present. They form at a neutral to alkaline pH of the urine. Bacterial infections contribute to their formation by increasing the pH of the urine through the urease
Urease
Urease is an enzyme that catalyzes the hydrolysis of urea into carbon dioxide and ammonia. The reaction occurs as follows:In 1926, James Sumner showed that urease is a protein. Urease is found in bacteria, yeast, and several higher plants. The structure of urease was first solved by P.A...
enzyme in dogs. More than 90 percent of dogs with struvite stones have an associated urease-producing bacterial infection in the urinary tract, but in cats struvite stones usually form in sterile urine. The appearance of the stones vary from large solitary stones to multiple smaller stones. They can assume the shape of the bladder or urethra.
Acidifier
Acidifiers are inorganic chemicals that either produce or become acid.These chemicals increase the level of gastric acid in the stomach when ingested, thus decreasing the stomach pH.These are many types of acidifiers but the main four types are:...
s. Special diets for dissolution also have reduced protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
, phosphorus
Phosphorus
Phosphorus is the chemical element that has the symbol P and atomic number 15. A multivalent nonmetal of the nitrogen group, phosphorus as a mineral is almost always present in its maximally oxidized state, as inorganic phosphate rocks...
, and magnesium
Magnesium
Magnesium is a chemical element with the symbol Mg, atomic number 12, and common oxidation number +2. It is an alkaline earth metal and the eighth most abundant element in the Earth's crust and ninth in the known universe as a whole...
, as well as increased salt to increase water consumption and dilute the urine. The diet needs to be fed exclusively, but it can only be fed for a few months total due to potential side effects. Contraindication
Contraindication
In medicine, a contraindication is a condition or factor that serves as a reason to withhold a certain medical treatment.Some contraindications are absolute, meaning that there are no reasonable circumstances for undertaking a course of action...
s to this diet include heart failure, liver failure
Liver failure
Acute liver failure is the appearance of severe complications rapidly after the first signs of liver disease , and indicates that the liver has sustained severe damage . The complications are hepatic encephalopathy and impaired protein synthesis...
, kidney failure, pancreatitis
Pancreatitis
Pancreatitis is inflammation of the pancreas. It occurs when pancreatic enzymes that digest food are activated in the pancreas instead of the small intestine. It may be acute – beginning suddenly and lasting a few days, or chronic – occurring over many years...
, hypertension
Hypertension
Hypertension or high blood pressure is a cardiac chronic medical condition in which the systemic arterial blood pressure is elevated. What that means is that the heart is having to work harder than it should to pump the blood around the body. Blood pressure involves two measurements, systolic and...
(high blood pressure), and hypoalbuminemia
Hypoalbuminemia
Hypoalbuminemia is a medical condition where levels of albumin in blood serum are abnormally low. It is a specific form of hypoproteinemia.Albumin is a major protein in the human body, making up about 60% of total human plasma protein by mass...
(low serum albumin
Serum albumin
Serum albumin, often referred to simply as albumin is a protein that in humans is encoded by the ALB gene.Serum albumin is the most abundant plasma protein in mammals. Albumin is essential for maintaining the osmotic pressure needed for proper distribution of body fluids between intravascular...
). Prevention of struvite stones is with a similar diet with milder restrictions.
Certain dog breeds are predisposed to struvite stones, including Miniature Schnauzer
Miniature Schnauzer
The Miniature Schnauzer is a breed of small dog of the Schnauzer type that originated in Germany in the mid-to-late 19th century. Miniature Schnauzers developed from crosses between the Standard Schnauzer and one or more smaller breeds such as the Poodle and Affenpinscher.The breed remains one of...
s, Bichon Frise
Bichon Frisé
A Bichon Frise , is a small breed of dog of the Bichon type. They are popular pets, similar in appearance to, but larger than, the Maltese.-Etymology and History:...
s, and Cocker Spaniels. They are the most commonly reported bladder stone in female dogs and in ferret
Ferret
The ferret is a domesticated mammal of the type Mustela putorius furo. Ferrets are sexually dimorphic predators with males being substantially larger than females. They typically have brown, black, white, or mixed fur...
s (pregnant ferrets may be especially predisposed). For frequency in cats, see below.
Calcium oxalate stones
Calcium oxalate
Calcium oxalate is a chemical compound that forms needle-shaped crystals, known in plants as raphides. A major constituent of human kidney stones, the chemical is also found in beerstone, a scale that forms on containers used in breweries...
stones form in an acidic to neutral urine. Two types naturally occur, calcium oxalate monohydrate, or whewellite
Whewellite
Whewellite is a mineral, hydrated calcium oxalate, formula CaC2O4·H2O. Because of its organic content it is thought to have an indirect biological origin and this is supported by it being found in coal and sedimentary nodules. However, it has also been found in hydrothermal deposits where a...
(CaC2O4·H2O), and calcium oxalate dihydrate, or weddellite
Weddellite
Weddellite is a mineral form of calcium oxalate named for occurrences of millimeter-sized crystals found in bottom sediments of the Weddell Sea, off Antarctica...
(CaC2O4·2H2O). Their appearance can be rough, smooth, spiculated
Spicule
Spicules are tiny spike-like structures of diverse origin and function found in many organisms, such as the copulatory spicules of certain nematodes or the grains on the skin of some frogs.In sponges, spicules perform a structural function....
, or jacks
Jacks
Jacks is a playground game for children....
tone. Calcium oxalate stones form more readily in animals with hypercalcaemia
Hypercalcaemia
Hypercalcaemia is an elevated calcium level in the blood. . It can be an asymptomatic laboratory finding, but because an elevated calcium level is often indicative of other diseases, a workup should be undertaken if it persists...
, which can caused by Addison's disease
Addison's disease
Addison’s disease is a rare, chronic endocrine disorder in which the adrenal glands do not produce sufficient steroid hormones...
or certain types of cancer
Cancer
Cancer , known medically as a malignant neoplasm, is a large group of different diseases, all involving unregulated cell growth. In cancer, cells divide and grow uncontrollably, forming malignant tumors, and invade nearby parts of the body. The cancer may also spread to more distant parts of the...
. Hypercalcaemia results in hypercalciuria
Hypercalciuria
Hypercalciuria or hypercalcinuria is the condition of elevated calcium in the urine. Chronic hypercalcinuria may lead to impairment of renal function, nephrocalcinosis, and renal insufficiency....
, which can also be caused by Cushing's syndrome
Cushing's syndrome
Cushing's syndrome is a hormone disorder caused by high levels of cortisol in the blood. This can be caused by taking glucocorticoid drugs, or by tumors that produce cortisol or adrenocorticotropic hormone or CRH...
or hyperparathyroidism
Hyperparathyroidism
Hyperparathyroidism is overactivity of the parathyroid glands resulting in excess production of parathyroid hormone . The parathyroid hormone regulates calcium and phosphate levels and helps to maintain these levels...
.
There is no recommended diet to dissolve calcium oxalate stones. For prevention a diet low in protein and oxalate
Oxalate
Oxalate , is the dianion with formula C2O42− also written 22−. Either name is often used for derivatives, such as disodium oxalate, 2C2O42−, or an ester of oxalic acid Oxalate (IUPAC: ethanedioate), is the dianion with formula C2O42− also written (COO)22−. Either...
s and high in magnesium, phosphorus, and calcium is recommended. Increased dietary magnesium and phosphorus decreases the amount of calcium in the urine, and increased dietary calcium reduces absorption of oxalates from the intestines. Potassium citrate
Potassium citrate
Potassium citrate is a potassium salt of citric acid with the molecular formula C6H5K3O7. It is a white, slightly hygroscopic crystalline powder. It is odorless with a saline taste....
has been recommended as a preventative for calcium oxalate stone formation because it forms a soluble complex with oxalates and promotes the formation of alkaline urine.
Dog breeds possible prone to calcium oxalate stones include Miniature Schnauzer
Miniature Schnauzer
The Miniature Schnauzer is a breed of small dog of the Schnauzer type that originated in Germany in the mid-to-late 19th century. Miniature Schnauzers developed from crosses between the Standard Schnauzer and one or more smaller breeds such as the Poodle and Affenpinscher.The breed remains one of...
s, Lhasa Apso
Lhasa Apso
The Lhasa Apso is a non-sporting dog breed originating in Tibet. It was bred as an interior sentinel in the Buddhist monasteries, who alerted the monks to any intruders who entered...
s, Yorkshire Terrier
Yorkshire Terrier
The Yorkshire Terrier is a small dog breed of terrier type, developed in the 19th century in the county of Yorkshire, England to catch rats in clothing mills. The defining features of the breed are its size, to , and its silky blue and tan coat...
s, Miniature Poodles, Shih Tzu
Shih Tzu
The Shih Tzu is a breed of dog weighing with long silky hair. The breed originated in China and is among the earliest breeds. Shih Tzu were officially recognized by the American Kennel Club in 1969...
s, and Bichon Frise
Bichon Frisé
A Bichon Frise , is a small breed of dog of the Bichon type. They are popular pets, similar in appearance to, but larger than, the Maltese.-Etymology and History:...
s. They are the most common stone in male dogs. Calcium oxalate stones are also common in domestic rabbit
Domestic rabbit
A domestic rabbit, or more commonly known as simply the rabbit, is any of the several varieties of European rabbit that have been domesticated....
s. Rabbits are prone to hypercalciuria due to intestinal absorption of calcium not being dependent on vitamin D
Vitamin D
Vitamin D is a group of fat-soluble secosteroids. In humans, vitamin D is unique both because it functions as a prohormone and because the body can synthesize it when sun exposure is adequate ....
and a high fractional urinary excretion of calcium. The urine will appear thick and creamy or sometimes sandy. Small stones and sand can be removed using urohydropropulsion. Prevention is through reducing calcium intake by feeding more hay and less commercial rabbit pellets, and by not using mineral supplements.
Frequency of struvite and calcium oxalate stones in cats
The Minnesota Urolith Center at the University of MinnesotaUniversity of Minnesota
The University of Minnesota, Twin Cities is a public research university located in Minneapolis and St. Paul, Minnesota, United States. It is the oldest and largest part of the University of Minnesota system and has the fourth-largest main campus student body in the United States, with 52,557...
College of Veterinary Medicine has done detailed analysis of uroliths from animals since 1981 and has noted changing trends in feline uroliths. In 1981, struvite stones were the most common type in cats, making up 78 percent of submitted samples, with only 2 percent comprising calcium oxalate stones. In the mid 1980s there was a substantial increase in the number of calcium oxalate samples, and between 1994 and 2002, 55 percent of feline stones were calcium oxalate and 33 percent were struvite. This may have been caused by the use of dissolution diets for struvite stones in cats and modification of other diets to prevent struvite crystal formation. These modifications predisposed to calcium oxalate crystal formation. However in 2004, struvite stones once again surpassed calcium oxalate stones 44.9 percent to 44.3 percent, and in 2006, 50 percent of stones were struvite and 39 percent were calcium oxalate. This may have been due to the increased use of diets designed to prevent calcium oxalate crystal formation, which because of increased magnesium in the diet and decreased acidity of the urine help promote struvite crystal formation.
Urethra
Urethra
In anatomy, the urethra is a tube that connects the urinary bladder to the genitals for the removal of fluids out of the body. In males, the urethra travels through the penis, and carries semen as well as urine...
l plugs in cats are usually composed of struvite crystals and organic matter.
Urate stones
Uric acid
Uric acid is a heterocyclic compound of carbon, nitrogen, oxygen, and hydrogen with the formula C5H4N4O3. It forms ions and salts known as urates and acid urates such as ammonium acid urate. Uric acid is created when the body breaks down purine nucleotides. High blood concentrations of uric acid...
in the urine. Dalmatian
Dalmatian (dog)
The Dalmatian is a breed of dog whose roots are often said to trace back to Dalmatia, a region of Croatia where the first illustrations of the dog have been found. The Dalmatian is noted for its unique black- or brown-spotted coat and was mainly used as a carriage dog in its early days...
s (especially males) and to a lesser extent Bulldog
Bulldog
Bulldog is the name for a breed of dog commonly referred to as the English Bulldog. Other Bulldog breeds include the American Bulldog, Olde English Bulldogge and the French Bulldog. The Bulldog is a muscular heavy dog with a wrinkled face and a distinctive pushed-in nose...
s are genetically predisposed to the formation of urate stones because of an altered metabolism of purine
Purine
A purine is a heterocyclic aromatic organic compound, consisting of a pyrimidine ring fused to an imidazole ring. Purines, including substituted purines and their tautomers, are the most widely distributed kind of nitrogen-containing heterocycle in nature....
s. Dalmatians have a decreased rate of urate hepatic transport, leading to only about 30 to 40 percent conversion of urate to allantoin
Allantoin
Allantoin is a chemical compound with formula C4H6N4O3. It is also called 5-ureidohydantoin or glyoxyldiureide. It is a diureide of glyoxylic acid....
, compared with greater than 90 percent conversion in other breeds. Dogs with portosystemic shunt
Portosystemic shunt
A portosystemic shunt , also known as a liver shunt, is a bypass of the liver by the body's circulatory system. It can be either a congenital or acquired condition....
s or endstage liver disease also have increased uric acid excretion in the urine due to reduced conversion of uric acid to allantoin
Allantoin
Allantoin is a chemical compound with formula C4H6N4O3. It is also called 5-ureidohydantoin or glyoxyldiureide. It is a diureide of glyoxylic acid....
and ammonia
Ammonia
Ammonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...
to urea
Urea
Urea or carbamide is an organic compound with the chemical formula CO2. The molecule has two —NH2 groups joined by a carbonyl functional group....
. Urate stones make up about six percent of all stones in the cat.
Urate stones can be dissolved using a diet with reduced purines that alkalinizes and dilutes the urine. Allopurinol
Allopurinol
Allopurinol is a drug used primarily to treat hyperuricemia and its complications, including chronic gout.- Mechanism of action :...
is used in dogs with altered purine metabolism to prevent the formation of uric acid. Feeding a diet high in purines while simultaneously administering allopurinol can result in the formation of xanthine
Xanthine
Xanthine , is a purine base found in most human body tissues and fluids and in other organisms. A number of stimulants are derived from xanthine, including caffeine and theobromine....
(C5H4N4O2) stones.
Cystine stones
CystineCystine
Cystine is a dimeric amino acid formed by the oxidation of two cysteine residues that covalently link to make a disulfide bond. This organosulfur compound has the formula 2. It is a white solid, and melts at 247-249 °C...
((SCH2CHNH2COOH)2) stones form in an acidic to neutral urine. They are usually smooth and round. They are caused by increased urine excretion of cystine (a relatively insoluble amino acid) in dogs with a defect in renal tubule reabsorption of cystine. Dietary reduction of protein and alkalinization of the urine may help prevent formation. Medications such as D-penicillamine and 2-MPG contain thiol
Thiol
In organic chemistry, a thiol is an organosulfur compound that contains a carbon-bonded sulfhydryl group...
, which forms a soluble complex with cystine in the urine. Dog breeds possibly predisposed to formation of cystine stones include Bulldogs, Dachshund
Dachshund
The dachshund is a short-legged, long-bodied dog breed belonging to the hound family. The standard size dachshund was bred to scent, chase, and flush out badgers and other burrow-dwelling animals, while the miniature dachshund was developed to hunt smaller prey such as rabbits...
s, Basset Hound
Basset Hound
The Basset Hound is a short-legged breed of dog of the hound family. They are scent hounds, bred to hunt rabbits and hare by scent. Their sense of smell for tracking is second only to that of the Bloodhound....
s, Chihuahua
Chihuahua (dog)
The ' is the smallest breed of dog and is so named for the state of Chihuahua in Mexico. Chihuahuas come in a wide variety of sizes, head shapes, colors and coat lengths.-History:...
s, Yorkshire Terriers, Irish Terrier
Irish Terrier
The Irish Terrier is a dog breed from Ireland, one of many breeds of Terrier.The Irish Terrier is an active and compactly sized dog that is suited for life in both rural and city environments. Its harsh red coat protects it from all kinds of weather....
s, and Newfoundland
Newfoundland (dog)
The Newfoundland is a breed of large dog. Newfoundlands can be black, brown, gray, or black and white. They were originally bred and used as a working dog for fishermen in the Dominion of Newfoundland, now part of Canada. They are known for their giant size, tremendous strength, calm dispositions,...
s. In Newfoundlands, cystinuria is inherited as an autosomal recessive trait, but in the other breeds it is a sex linked
Sex linkage
Sex linkage is the phenotypic expression of an allele related to the chromosomal sex of the individual. This mode of inheritance is in contrast to the inheritance of traits on autosomal chromosomes, where both sexes have the same probability of inheritance...
trait and found primarily in male dogs.
Calcium phosphate stones
Calcium phosphateCalcium phosphate
Calcium phosphate is the name given to a family of minerals containing calcium ions together with orthophosphates , metaphosphates or pyrophosphates and occasionally hydrogen or hydroxide ions ....
, also known as hydroxyapatite (Ca10(PO4)6(OH)2), stones form in neutral to alkaline urine. They are usually smooth and round. Calcium phosphate is usually a component of struvite or calcium oxalate stones and is infrequently a pure stone. They form more readily with hypercalcaemia. Dog breeds possibly predisposed to calcium phosphate stone formation include Yorkshire Terriers, Miniature Schnauzers, and Cocker Spaniels.
Silicate stones
SilicateSilicate
A silicate is a compound containing a silicon bearing anion. The great majority of silicates are oxides, but hexafluorosilicate and other anions are also included. This article focuses mainly on the Si-O anions. Silicates comprise the majority of the earth's crust, as well as the other...
(SiO2) stones form in acidic to neutral urine. They are usually jackstone
Jacks
Jacks is a playground game for children....
in appearance. There is possibly an increased incidence associated with dogs on diets that have a large amount of corn gluten
Gluten
Gluten is a protein composite found in foods processed from wheat and related grain species, including barley and rye...
or soybean
Soybean
The soybean or soya bean is a species of legume native to East Asia, widely grown for its edible bean which has numerous uses...
hulls. Dog breeds possibly predisposed include German Shepherd Dog
German Shepherd Dog
The German Shepherd Dog , also known as an Alsatian or just the German Shepherd, is a breed of large-sized dog that originated in Germany. The German Shepherd is a relatively new breed of dog, with its origin dating to 1899. As part of the Herding Group, the German Shepherd is a working dog...
s, Golden Retriever
Golden Retriever
The Golden Retriever is a medium-sized breed of dog. They were historically developed as gundogs to retrieve shot waterfowl such as ducks and upland game birds during hunting and shooting parties. As such, they were bred to have a soft mouth to retrieve game undamaged and have an instinctive love...
s , Labrador Retriever
Labrador Retriever
The Labrador Retriever is one of several kinds of retriever, a type of gun dog. A breed characteristic is webbed paws for swimming, useful for the breed's original purpose of retrieving fishing nets. The Labrador is the most popular breed of dog by registered ownership in Canada, the United...
s, and Miniature Schnauzers.