Kidney Stones

Kidney stones and the related diseases are common in dogs.

Kidney stones that pass through the bladder can cause bladder-lining irritation and can lead to total urinary blockage.

Poor diet is one cause of this condition; it is believed that pets that eat only dry food, or have excessive mineral content in their diet are at risk for this ailment.

We suggest Uro Solution, distilled water and speaking with a person with experience with raw food diets that help with canine kidney stones.

Symptoms to look for are: frequent urination (often in unusual places), bloody urine, dribbling urine, straining when urinating, weakness, depression and pain.

Dogs often suffer from kidney and bladder stones (calculi or uroliths) very similar to those found in humans. Most of these stones are composed of the mineral salts of common elements found in the body, calcium, magnesium, ammonia, phosphorus and carbonates. Their composition and consistency are similar to that of limestone.

Causes Of Bladder And Kidney Stones:

Several factors contribute to the formation of urinary tract stones. If the concentration of mineral salts are too high in the urine, they precipitate out, layer upon layer, in the kidneys or farther down the tract in the bladder. The urine of dogs should be naturally acidic.

Most mineral salts are less soluble in alkaline urine so any factors that make the urine more basic or alkaline contribute to stone formation. Many bacteria decompose urine urea into ammonia and so alkalinize the urine. Like pearls, mineral salts come out of solution easier if they have a small object to attach to. That is why the debris of urinary tract infections often serve as foci for forming stones.

Specific breeds and lines of dogs are susceptible to stones of different compositions. These stones are formed from the salts of amino acids and urates that occur in the blood of these dogs in too high a concentration. The best-known example of this are the ammonium urate stone formed by Dalmatians.

To this day we do not know why some dogs form bladder and kidney stones and others do not. Dehydration increases the concentration of minerals within the urine and can increase stone formation. Female animals of all species are more susceptible to urinary tract infections and subsequent stones due to their shorter urethra. Other dogs are born with mucosal immunity defects that leave them more susceptible to urinary tract infection.

Signs Of Bladder Stones:

The two most common signs of bladder stones are blood in the urine and painful urination. Blood in the urine or hematuria occurs when stones irritate the bladder’s sensitive lining causing bleeding.

The inflamed bladder lining is quite painful as are the small sand-like stones that pass out with the urine. Dogs with bladder stones attempt to urinate much too frequently. They will squat and strain with no apparent success. The urine may be red or port wine in color.

When they do urinate, the quantity of urine is small. In between urination these pets are restless. They walk with their loins down in a crouched position. Owners may misinterpret these signs and assume the pet is constipated. A trained DVM can palpate the abdomen of these animals and often feel small stones in the bladder grinding together like marbles. Large solitary stones in the bladder are even harder to miss.

If a veterinarian does not attend to this problem immediately, one of the stones may obstruct the urethra, the tube leading from the bladder to the penis or vagina. When this happens, urine backs up into the body causing uremia, depression and vomiting. The bladder stretches to several times it normal size and may even burst. It may take weeks after the problem is relieved for the bladder’s tone and size to return to normal.

Blood taken from obstructed animals has elevated urea and creatinine and its ionic balance is disrupted. Despite these changes, dogs with stones do not run high fevers. Analysis of the urine of these pets usually finds blood and white blood cells. Bacteria may also be present in the urine. Any urinary tract infection that reoccurs frequently should be checked carefully for the presence of bladder or kidney stones. These stones are porous and bacteria reside within them where antibiotics and the body’s immune system cannot easily reach them. That is why infections frequently reoccur.

Somewhat less common are stones that form in the kidneys. These stones may cause sudden colic and intermittent bloody urine or may occur without any visible symptoms. Occasionally, stones will leave the kidney plugging the ureters, the tubes that lead to the bladder. This event is marked by severe pain, agitation and straining until the stone has passed or been surgically removed.

Most of these stones are quite visible on x-rays. Occasionally the stones contain more organic material than mineral and are difficult to visualize.  Ultrasound will also detect these radiolucent stones. 

Prevention and Elimination of Kidney Stones:

Stones should be sent to a laboratory for analysis. All stones are less likely to form if your pet has free access to water and frequent opportunities to urinate. Stones are less likely in dilute urine. Adding one quarter teaspoon-full of salt to one pint of water that your pet consumes will increase the amount of water it drinks.

We also suggest URO Solution, distilled water and speaking to someone familiar with raw food diets for canine kidney stones.

Eliminating bacterial urinary tract infections and checking (bacterial culture and sensitivity) the urine of dogs prone to them twice a year helps prevent stones that occur due to the alkaline urine infections cause.

Diets high in grain and vegetables produce alkaline urine, which allows certain stones to form. This is one of many reasons to see to it that your pet eats a commercially prepared diet.

Calcium Oxalate stones seem to be getting quite common and are very frustrating to treat. They differ from struvite stones in that they form in acidic urine. Unfortunately, they are harder to prevent through dietary manipulation than struvite or urate calculi (stones).

They are much more common in male dogs (75%) and Burmese, Himalayan and Persian cats. The most common dog breeds affected are Yorkshire terriers, poodles, shih tzus, schnauzers, lhasa apsos and bichon frises. These stones are associated with excess calcium in the blood and urine. Sometimes these stones are the result of other diseases such as Cushing’s disease or the excessive use of corticosteroid medications.

Many mineral salts are excreted in urine at concentrations at which they would normally fall out of solution and form granules or stones. One substance, produced by the kidneys, called nephrocalcin (an acidic glycoprotein) inhibits stone formation. When too little of this chemical is produced, stones may result.