Urinary Tract / Kidney Stones (Calcium Phosphate) in Dogs

Urinary tract stones and kidney stones are made of different minerals and chemical compounds. Many of these stones require the same form of treatment after the diagnosis. Stones that are within the bladder are called urolithiasis, and stones that occur in the kidneys are known as nephroliths. Bladder stones, rather than kidney stones, are more common in dogs; however, calcium phosphate stones are more commonly found in the kidneys than in the bladder.

Urolithiasis is a painful disorder where uroliths, or stones, are present in the urinary tract and bladder, and nephroliths are stones which are present in the kidneys. Both types of stones are caused by the calcification of minerals and mineral compounds that build up in the kidneys and bladder.

Urinary tract or kidney stones have several unique symptoms, and some of them are quite noticeable to the dog owner, alerting them that something could be wrong. Symptoms include:

• Increased, sporadic urination
• Difficulty urinating
• Pain, or straining, when urinating 
• Blood or pus in the urine
• Restlessness, or pacing, looking for a place to urinate
• Urinating in different places than usual
• Malaise

Types

There are different types of stones made up of various minerals and compounds that can cause bladder and kidney stones. In addition to calcium phosphate, kidney and bladder stones can be comprised of:

• Ammonium acid urate
• Sodium urate
• Uric acid
• Calcium oxalate
• Cystine (cystinuria)
• Struvite (magnesium ammonium phosphate)
• Xanthine
• Calcium phosphate
• Silica

Causes of this illness can be directly related to diet, since the urine of the dog needs to be kept at a certain pH balance and be diluted. If the minerals do not get dissolved properly, then the crystals will form stones. Causes of bladder and kidney stones in dogs include:

• High calcium diet
• Not enough fresh water to drink dail
• Mineral supplements, such as Vitamin D
• Genetics
• Bacterial infections in kidneys or bladder
• Irregular urine pH
• Infection of the urinary tract
• Excessive mineral salts in the urine

If you see any of the symptoms above, or if your canine is acting abnormally in any way, a call to the veterinarian will be your best option in getting a quick diagnosis and treatment. Your veterinarian may ask that you bring the dog in immediately if he is showing signs of severe pain or the inability to urinate, which can be a blockage. Your veterinarian may request that you bring in a free-catch urine sample (if you can get one), but that may just be an option and it depends on the specific situation and symptoms.

Once the veterinarian had completed a thorough physical examination, including asking about the medical history, he will perform tests. Tests can include a complete blood count, urinalysis, electrolyte testing, and blood chemical testing. 

The veterinarian may find that diagnosing the dog with stones may be as simple as palpitating on the bladder area, as some stones can be felt by a medical professional. For stones that are harder to diagnose, the veterinarian may perform imaging techniques on the dog’s abdomen, such as an x-ray, ultrasound. Your veterinary caregiver may opt to use a special dye which is put into the bladder to allow the stones to be seen more effectively on an x-ray.

Treatment for this condition can be non-surgical, surgical, or dietary. Treatment options are:

Diet and Medication

If your dog has kidney or bladder stones, there are antibiotics that can be given to allow for them to dissolve. Medication is given along with a prescription diet that encourages more liquids to enter the body. The decision to give medication is determined by the diagnosis of the stones, how large the stones are, and if the urethra is not obstructed by the stones.

Surgery

When the dog has a blocked urethra, this is life-threatening. Surgery is the only option in cases of emergencies such as this. When the stones are very large, surgery may need to be performed to open the bladder and remove them.

Urohydropropulsion

The insertion of a catheter that fills the bladder with saline is quite effective in flushing out very small stones. This process of urohydropropulsion is performed when the veterinarian is sure the stones can be passed through the urethra.

When a dog has been diagnosed and successfully treated for urinary tract or kidney stones, there needs to be a lifelong commitment to recovery. Even if the dog is “cured” of the stones, they can, and most likely will, reappear if a special diet is not followed.

Fortunately, there are prescription foods that are formulated to reduce the risks of mineral and stone formation in dogs. They keep the urine at a healthy pH level and deliver the proper amount of minerals and protein to the dog’s diet. The prescription food for bladder and kidney stones is also very moist, so the dog gets plenty of hydration through eating the food. In addition to this, fresh water each day is very important in keeping stones at bay.

Knowing the symptoms of urinary tract or kidney stones allows you to continue to be proactive in maintaining your dog’s health, and following a special diet will allow you and your dog to enjoy many more years together.