Kidney Stones in Cats

About

Also known as nephroliths, kidney stones are rock-like formations that accumulate in the kidneys. There are different types of kidney stones and can be made up of struvite, calcium oxalate, urate, bile pigment, and calcium phosphate. The most common type of kidney stone is calcium oxalate.

The kidneys are two bean-shaped organs located near the spine in the abdomen which is made up of tiny filtering units called nephrons. Kidneys filter the blood to remove waste products, these are excreted out of the body via the urine.

Causes

There are several causes of kidney stones including dietary factors, urine retention (holding on too long to urinate), recurring urinary tract infections, certain medications, and genetics.

Symptoms

Cats with small stones may display no symptoms at all. Problems occur when stones pass from the kidney into the ureter and form a partial or full blockage.

• Straining to urinate
• Licking at the genitals
• Crying in the litter tray
• Frequent urination, often passing only small amounts of urine
• Blood in the urine
• Abdominal pain
• Vomiting
• Depression
• Enlarged kidneys due to fluid backing up in the kidneys

This is a medical emergency, a blockage can cause irreversible damage to the kidneys, along with a build-up of toxins in the bloodstream (uremia). Seek immediate veterinary care.

Diagnosis

The veterinarian will perform a physical examination, which may reveal swollen and/or tender kidneys. He will obtain a medical history from you including any symptoms you have noticed.

Diagnostic workup:

• Ultrasound or x-rays, which may reveal the presence of kidney stones
• Complete blood count
• Urinalysis to check kidney function, and may also reveal blood in the urine, bacteria, and the presence of small kidney stones
• Analysis of the stones

Treatment

Treatment will depend on the type of stones present, and if the cat is symptomatic. In some cases, there may be no treatment. However, where treatment is necessary, it may include:

• Medication or diet to dissolve the stones.
• Severe cases will require surgery to remove the stones.
• Extracorporeal shock wave lithotripsy (ESWL) is a technique using sound waves to break up the stones.
• Increase your cat’s water consumption to dilute the urine.
• Ensure your cat always has access to a clean litter tray so that he doesn’t hold onto urine for too long.

A cat who is blocked will need to be catheterised. Uremia is life-threatening and the cat will need to be stabilised first with IV fluids to treat fluid and electrolyte imbalances.

Cats will need to return to their veterinarian regularly for monitoring as kidney stones often will return. The test will include X-rays, urinalysis, and blood work. It will be necessary to monitor your cat’s urine pH and concentration.