Nephrolithiasis (Kidney Stones) in Dogs

Nephrolithiasis is the condition marked by the presence of renal calculi or kidney stones.

One function of the urinary system is the removal of body wastes in liquid form. Some mineral wastes are only slightly soluble and may form crystals. If the transit time of crystal movement through the urinary system is prolonged, crystals may interact and grow into stones.

Causes

Several types of stones can affect cats and dogs. Each type of stone is often associated with its own specific cause. General causes include:

Underlying urinary tract infections or infection within the kidney

Genetic defects

Dietary factors or supplements

Administration of certain medications

Concurrent or underlying conditions or illness

Overall, kidney stones are slightly more common in the female dog and are generally seen in the middle-aged animal, although they can be seen in any age. There are different breed predilections for each type of calculi, and in the dog, although any breed can be affected, there is a predilection for the miniature schnauzer, miniature, poodle, Yorkshire terrier, Lhasa apso, shih tzu, bichon and cocker spaniel.

Urine retention and the formation of concentrated urine may predispose to calculi.

What to Watch For

Bloody urination

Abdominal pain

Recurrent urinary tract infections

Vomiting

Clinical signs depend on the exact location, size, shape and number of kidney stones. Affected individuals may have no clinical signs. Other signs such as painful urination or frequent urination may be seen in patients who have a concurrent lower urinary tract infection. Some patients may be extremely ill if they have associated kidney failure or severe infection.

Diagnosis

Complete blood count (CBC)

Biochemical profile

Urinalysis

Bacterial urine culture

Radiographs (X-rays)

Abdominal ultrasound or excretory urography

Treatment

Depending on the patient, recommended treatment options may vary.

Inactive nephroliths may only require periodic monitoring.

If the stones are an incidental finding or the pet is not having severe clinical signs, medical and/or dietary dissolution may be attempted. It is important for both you and your veterinarian to monitor your pet very closely during this period, as it is possible that not all stones can or will dissolve.

If the patient is in kidney failure or is having severe clinical signs associated with the presence of the stones, their removal, either surgical or by lithotripsy, would be recommended.

Antibiotic therapy is indicated in those patients with concurrent urinary tract infections.

Fluid therapy is indicated in those patients who are dehydrated, have severe infections, or have concurrent kidney failure.

Home Care

If your pet is on a stone dissolving diet, complete compliance is necessary. NO snacks or other diets are permitted, as these may negate the beneficial effects of the special diet. Administer all medication and return for follow-up as directed by your veterinarian.

If your pet is being treated for nephrolithiasis and suddenly seems ill, contact your veterinarian at once.

Preventative Care

Eliminating urinary tract infections may help prevent nephrolithiasis. Treating and controlling underlying disorders may help prevent recurrence of stones.