Dogs and cats, like humans, can develop bladder and kidney stones.
Bladder stones are rock-like collections of minerals that form in the urinary bladder. These stones can obstruct the outflow of urine when they block the neck of the bladder or get lodged in the narrow urethra.
types of BLADDER STONES
Bladder stones may be in the form of a single large stone or multiple small stones. They can rub and damage the lining of the bladder or urethra , causing painful inflammation and bleeding. Cats with bladder stones often strain to urinate and pass out blood in urine.
The 2 most common types of bladder stones are:
1. STRUVITE STONES
- more likely to develop in alkaline urine
- made up of magnesium, ammonium and phosphate
- can be dissolved by prescription diet
- prescription diet low in magnesium to produce a more acidic (low pH) urine to dissolve the crystals or stones
2. OXALATE STONES
- more likely to develop in acidic urine
- could be caused by excessive intake of calcium, protein, sodium or Vitamin D
- cannot be dissolved by diet
- prescription diet to minimise calcium oxalates in urine and produce a more alkaline (high pH) urine
How do bladder stones form?
Certain diets or diseases in the bladder may cause an increased level of stone-forming minerals in the urine. When the concentration of such minerals becomes very high, the undissolved particles unite and form tiny crystals. As more crystals join together, they gradually enlarge into stones.
How are bladder stones diagnosed?
- Palpation: Some bladder stones can be palpated (felt) through the abdominal wall.
- Urinalysis: To check urine pH and detect presence of blood, bacteria and crystals.
- X-Ray: Most bladder stones are visible on X-Ray.
- Ultrasound: Stones that are radiolucent (not visible on X-Ray) can be detected by ultrasound.
How are bladder stones treated?
1. PRESCRIPTION DIET
- Usually prescribed to dissolve struvite stones (not effective for other types of stones)
- Slow to work and not the best option if your pet is already in pain or there is life-threatening obstruction
- Must be fed exclusively for it to be effective but not all pets will eat the prescription diet
Very small stones can be flushed out of the bladder via a non-surgical procedure called voiding urohydropropulsion – using a liquid to expel something from the urinary tract.
- A sterile urinary catheter is placed via the urethra.
- Saline solution is instilled into the bladder. * Avoid over distending or rupturing the bladder.
- The bladder is manually expressed to flush out the stones.
Larger stones need to be removed surgically through an operation called a cystotomy.
The bladder stones should be sent to the laboratory for analysis to determine if prescription diet will be helpful in lowering the chance of recurrence. Regular urine tests and ultrasound are useful. There are also medications to control urine pH and bacterial infections. However, it is not uncommon for bladder stones to recur. Some breeds are genetically predisposed to developing stones.
How can we help prevent bladder stones in our cats?
- Provide plenty of fresh water at all times to keep your cat well hydrated so that the urine is dilute.
- Keep litter trays in a quiet and safe area in the house.
- Keep litter trays clean.
- If you have more than one cat, provide more litter trays to encourage them to urinate frequently and freely without fear of “invading” another cat’s territory.