Urolithiasis, also known as urinary tract stones, is a collective term for kidney stones, ureteral stones, bladder stones and urethral stones. Clinically, it is characterized by difficulty urinating, pain at the obstruction site, and hematuria.

【Cause】

The reasons for the formation of urinary stones are not yet fully understood. It is generally believed to be related to factors such as monotonous food or excessive mineral content, insufficient drinking water, mineral metabolism disorders, changes in urine pH, urinary tract infections and lesions, etc.

Imbalance of colloid and crystal: Normal urine contains a variety of dissolved crystal salts (phosphate, urate, oxalate, etc.) and a certain amount of colloidal substances (mucin, nucleic acid, mucopolysaccharide, cystine acid, etc.), they maintain a relative equilibrium state. Once this balance is out of balance, that is, when the crystal exceeds the normal saturation concentration, or when the colloidal substance continuously loses its stable intermolecular structure, salt precipitation and colloid precipitation will occur in the urine, and then condense into stones.

Metabolic disorders: Such as hyperparathyroidism, excessive secretion of parathyroid hormone, etc., which can cause mineral metabolism disorders in the body, causing excessive urinary calcium, and factors such as excessive estrogen levels in the body, which can promote urinary stones. Formation.

Urinary tract lesions: Urinary tract lesions are an important condition for stone formation.

① When urinary tract is infected, urinary tract inflammation can cause tissue necrosis, coupled with the accumulation of inflammatory exudates and bacteria, the core of the stone can be formed, and the periphery is surrounded by mineral salts and colloidal substances that condense to form stones. In addition, many bacteria such as Staphylococcus, Proteus, and Salmonella can decompose urea into ammonia, making the urine alkaline, which can easily cause the precipitation of calcium phosphate, calcium carbonate, etc., which is conducive to the formation of urinary tract stones.

② When the urinary tract is obstructed, it can cause hydronephrosis, causing urine retention, which can easily lead to infection, crystal precipitation, and stone formation.

③When there are foreign bodies (sutures, catheters, blood clots, bacteria, exfoliated cells, etc.) in the urinary tract, they can become the core of stones, and crystalline salts in urine settle on their surfaces to form stones.

Urinary stones are mainly formed in the kidneys (renal tubules, renal calyces, renal pelvis), and then migrate to the bladder and continue to grow in the bladder. Therefore, the bladder is considered to be the most common place for urinary stones in dogs and cats. Most uroliths in the renal tubules are fixed, but stones in the renal pelvis or bladder are mobile, and some may cause obstruction when they migrate to the ureters and urethra. The blocked area of ​​the stone irritates the urinary tract mucosa, causing local mucosal damage, inflammation, and bleeding, causing the urinary tract smooth muscle to spasm and contract, causing renal abdominal pain. Difficulty urinating or anuria due to urinary tract obstruction, fluid accumulation in the bladder, leading to bladder paralysis or even rupture.

【Symptoms】

The clinical symptoms of urolithiasis are related to the obstruction location, size, andThe degree of tissue damage varies.

Kidney stones: They are mostly located in the renal pelvis. There are often no obvious symptoms in the early stage of kidney stone formation. Later, symptoms of pyelitis appear, such as hematuria, tenderness in the kidney area, slow walking, and a stiff and nervous gait. In severe cases, hydronephrosis can occur.

Ureteral stones: acute abdominal pain, vomiting, the affected dog or cat is unwilling to move, shows pain, arches its back when walking, and has pain on palpation of the abdomen. When the ureter is unilaterally or incompletely blocked, hematuria, pyuria, and proteinuria may be seen; if both ureters are completely blocked at the same time, anuria will enter the bladder, resulting in anuria or anuria, often leading to pyelonephritis.

Bladder stones: Sick dogs and cats have difficulty urinating, hematuria and frequent urination, but the amount passed out each time is small. Increased bladder sensitivity. When stones are located in the neck of the bladder, urination may be difficult and painful. Larger stones can often be felt upon palpation.

Urethral stones: mostly occur in male dogs and cats. When the urethra is incompletely blocked, urination will be painful, the urine will flow out in drops or intermittently, and sometimes there will be blood in the urine. If the urethra completely blocks the elbow, anuria and renal abdominal pain will occur. The bladder is extremely full, and the sick dog or cat tries hard but does not see urine being discharged. Prolonged time may cause bladder rupture or uremia.

【Diagnosis and differential diagnosis】

The diagnosis can be made based on clinical symptoms, urethral probing and X-ray examination results. Some bladder stones are accompanied by polyps or bladder tumors.

The common urinary stones in dogs and cats are as follows:

(1) Phosphate urinary stones: white or off-white, formed rapidly, can form antler-shaped stones, and often occur in alkaline mucus. X-ray imaging is faint.

(2) Oxalate urinary stones: brown in color, rough and spiny on the surface, hard in texture, easy to damage the urinary tract and cause hematuria, and occur in alkaline urine. The X-ray characteristics are that there are deep markings in the urinary stones, which are mulberry-shaped, with acupuncture-like edges and radiate outwards.

(3) Urate uroliths: light yellow in color, smooth in surface, hard in texture, often occur in acidic urine. X-ray imaging is faint.

(4) Cystine uroliths: The surface is smooth and can pass through X-rays. They are not easy to be visualized on X-rays, so they are called "translucent stones" and occur in acidic urine.

(5) Carbonate uroliths: white in color, crunchy in texture, occurring in alkaline urine.

【Treatment】

The treatment principle is to eliminate stones mainly and symptomatic treatment is supplemented.

Diet and drug treatment: For cases of incomplete obstruction or mild illness, foods with low mineral content and rich in vitamin A are given, combined with the traditional Chinese medicine Paishi Decoction, plenty of clean drinking water, and diuretics to dilute the urine.It can increase urinary output and flush the urinary tract so that small stones can be excreted with urine. For phosphate, oxalate and carbonate stones, acidic food or acid preparations (such as chloride plating, etc.) can be given to acidify the urine to promote the dissolution of the stones and the improvement of the condition. For urate and cystine stones, it is advisable to take sodium bicarbonate to alkalize the urine, which can also prevent stone formation and promote stone dissolution. In addition, for urate stones, 4 mg/kg of isosurinol can be taken orally daily to prevent urate coagulation. For cystine stones, D-penicillamine can be used at 15-30mg/kg per day to turn it into a soluble cystine complex and be excreted in the urine.

Surgical treatment: For larger stones and associated urinary tract obstruction, urethrotomy or cystotomy must be performed promptly to remove the stones. If there are bladder polyps or bladder tumors, they need to be surgically removed at the same time. If the stones are few and small, ultrasonic lithotripsy can be used.