Bladder stones in pets, or uroliths, are commonly found in dogs and cats, and can cause urinary tract infection and blockage. The bladder stones found in pets are very similar to those found in humans. Most of these stones are composed of mineral salts from common elements, including phosphorus, calcium, magnesium, ammonia, and carbonates. Stones may form in the bladder, often in varying size and number. Types of bladder stones include struvite, calcium oxylate, urate, cystine, calcium phosphate, and silicate stones.
Bladder stones normally do not affect the rest of your pet's body unless the stones break off or lodge in the urethra, leading to potential urinary tract obstruction. This is especially a risk for male pets with a narrower urethra. In these emergency situations, your pet may often experience intense pain, vomiting, and severe blood electrolyte abnormalities such as a high blood potassium, acute kidney failure, bacterial infection, and death within a few days, if the obstruction is not relieved.
Oversaturation of the urine with urine crystals is the biggest factor in stone formation in dogs and cats. This oversaturation may be caused by increased excretion of crystals by the kidney, increased water reabsorption by the kidneys, and changes in the urine PH leading to crystal formation. Other factors in stone formation include genetics, diet, frequency of urination, dehydration, and the presence of a urinary tract infection. A combination of these factors often leads to a nest of cells and debris where stone formation may occur.
Certain dog and cat breeds have an increased tendency of developing different types of bladder stones. For example, dog breeds predisposed to struvite stones include the Miniature Schnauzer, Bichon Frise, and Cocker Spaniel. Breeds prone to calcium oxylate stone formation include the Miniature Schnauzer, Shih Tzu, and Bichon Frise. Dalmations are genetically prone to develop urate stones. Burmese, Persian, and Himalayan cats may be at an increased risk of developing struvite or calcium oxylate stones.
Male pets are most at risk for urinary tract obstruction because of their narrower urethras. Female dogs and cats are more susceptible to urinary tract infections and subsequent stone formation due to their shorter urethras.