Why do Calcium Oxalate Uroliths form?
Genetics, dietary issues and some metabolic diseases can predispose pets to the formation of calcium crystals or stones. Pets that have more acidic (low) urine pH and very concentrated urine can be factors in calcium oxalate formation. Breeds especially at high risk include: schnauzers, lhasa apsos, yorkies, poodles, shih tzus, bichons, Burmese cats and Himalayan cats.
How do you diagnose calcium oxalate stones?
Although a urinalysis can provide clues (calcium crystals and acidic/low urine pH), and an ultrasound or x ray can confirm the presence of stones, the only way to know the exact stone type is to retrieve the stone(s) surgically (cystotomy) and have a laboratory analyze it.
Do the stones have to be surgically removed?
Unfortunately there is no diet nor medication that would be able to dissolve this type of stone. Leaving the stones in place will predispose your pet to frequent irritation to the bladder wall, infections and possibly life threatening blockage of the urinary tract. Because there are many factors that lead to calcium stone formation, and no foolproof way to prevent them from reforming, studies show that 50% of all pets who have had calcium stones removed will develop new stones within 3 years.
Therapeutic plan to minimize the chance of recurrence
Diet – while specific diets cannot dissolve existing stones, they do help in preventing the development of new stones. Canned form is preferred so as to increase water consumption and thus help dilute urine.
- To be effective, prescription diets must make up >90% of the total calories consumed.
- It is especially important to avoid table scraps, however the following treats are acceptable (in very small quantities) for calcium stone forming pets: plain cooked boneless skinless chicken/turkey breast, cooked eggs, rice, peas, white potatoes, cabbage, cauliflower and bananas.
Urinalysis and Recheck– urine needs to be checked at intervals to help ensure that the concentration and pH are adequate to help reduce risk of reforming stones and check for signs of infection. If pH and concentration are not adequately controlled with diet alone, occasionally other medications will need to be prescribed.
Calcium oxalate bladder stones can be very frustrating. Not only do they tend to recur (sometimes very quickly), management will involve frequent visits to the veterinarian’s office to recheck urine. Keep in mind the trouble and expense of a stone surgery outweighs the trouble and expense of monitoring.