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Kidney Stones in Cats: What You Need to Know

Posted June 01, 2015 in Cat Diseases & Conditions A-Z

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Kidney stones form in cats for a few different reasons. The different causes ultimately predict which type of nephro (kidney) + lith (stone) is most likely to form. And the type of stone affects what treatments might help. Cats with small kidney stones really may have no signs at all. Kidney stones may show up on x-rays of the belly that are being taken for unrelated reasons, as a so called “incidental” finding. Since kidney stones in cats don’t seem painful, why should we worry about them?

A kidney stone that allows normal urine flow out may be one that your vet watches closely, but ultimately leaves untreated. However, if the stone gets very large, or if little pieces break off and lodge in the ureter (the long narrow tube that connects each kidney to the urinary bladder), it likely becomes very painful. Kidney colic—signaled by abdominal pain, malaise and even vomiting—may result; the kidney may swell and be damaged. If this should happen simultaneously to each kidney, and the blockage persists, your kitty will likely become critically ill from the disrupted flow of urine. If you think your cat’s abdomen is painful, or his urinations change in any way, please contact your veterinarian right away. A urinary obstruction is a life threatening emergency that must be treated!

Signs of kidney stones in cats
The signs and symptoms of kidney stones could include:

Diagnosis of kidney stones in cats
Most stones usually show up readily on plain radiographs, but small stones may be hidden behind intestinal contents. Another reason that simple x-rays may not give enough information is because certain stones just don’t show up well.  An example would be a urate stone, which might occur as a result of liver disease. Once a stone has been diagnosed, your vet will want to do some tests to help with predicting the stone type. Tests are needed also to assess what impact the stone(s) may be having on your cat’s kidney health, and whether other conditions may be present that might increase the risk of stones. Testing may include:

  • Complete blood count (CBC)
  • Blood chemistry with electrolytes — Testing for evidence of kidney disease and risk factors for stone formation
  • Urinalysis— The urine quality may predict kidney disease and help identify bacterial infection or crystals that may help predict stone type
  • Urine culture with susceptibility— To identify bacterial infection and the best antibiotic choice(s)
  • Abdominal radiographs (x-rays)— To examine the size and shape of the kidneys and look for urinary stones
  • Systemic blood pressure— To identify an important complication of kidney disease
  • Abdominal ultrasound— This will help verify the location of any stones and the suspected degree of any obstruction
  • Contrast radiography— Dye studies may be needed to confirm blockage and help to show the contribution that each kidney makes to urine production.

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Celeste has more than 20 years of experience in the veterinary industry and is an Internal Medical Consultant as well as a valued member of IDEXX’s Pet Health Network team since 2015.