Urinary Tract / Kidney Stones (Cystine) in Dogs

By PetMD Editorial on Jul. 2, 2008

Urolithiasis (Cystine) in Dogs

Urolithiasis is a medical term referring to the presence of crystals or stones in the urinary tract. When the stones are made up of cystine – a normal compound found in the body – they are called cystine stones. These stones can also be found in the kidneys and in the tubes connecting the kidneys to the animal's bladder (ureters).

Urolithiasis affects both dogs and cats, and are primarily found in adult animals. As far as dogs breeds: Dachshunds, English Bulldogs, Newfoundlands, Staffordshire Bull Terriers, and Welsh Corgi Dogs are more susceptible to cystine stones. On the other hand, Siamese and domestic shorthairs show the highest likelihood for stone formation in cats.

In most cases, the stones can be dissolved and removed without surgery, giving the animal a positive prognosis.

Symptoms and Types

Typical symptoms can include increased frequency of urination (pollakiuria), difficulty or painful urination (dysuria), and an abnormal flow of urine (post-renal uremia).

Causes

The exact cause for urolithiasis is not currently known. In some animals, however, the inability to process proteins or amino acids has led to the development of cystine stones.

Diagnosis

Ultrasounds and X-rays are often performed to determine the size, shape, and location of the stones, helping the veterinarian come up with an appropriate treatment regimen. A urine test can also detect the presence of stones.

In some cases, a scope with a camera on the end (urethrascope) is used to examine the inside of the urinary tract for any abnormalities.

Treatment

The veterinarian will usually recommend using treatment options such as a special diet and medication -- N-(2-mercaptopropionyl)glycine (2-MPG) -- to reduce and eliminate the stones without surgery.

Living and Management

Follow all recommended dietary changes and administer prescribed medication. This will help prevent a recurrence of the stones. It is also important to bring the animal back to the veterinarian's office to ensure the stones have been successfully dissolved.