The condition where urinary calculi (uroliths) or stones form in the urinary tract is called urolithiasis. Just like in humans, the disease can cause extreme discomfort during urination and other associated symptoms. Uroliths can form anywhere in the dog’s urinary system (kidneys, ureters, bladder or urethra) but in 85% of cases the stones occur in the bladder. Stones are made up of minerals, commonly calcium oxalate, struvite, urate and cystine in dogs.
- High urine concentration: high protein diets and low water intake makes the urine more concentrated.
- The pH of urine: acidic urine favors the formation of calcium oxalate and urate crystals, while alkaline urine aids in development of struvite crystals.
- Genetic predisposition: if a dog’s pedigree chart information reveals that stone formation is a common trait, then their offspring will be prone to urolithiasis.
- Breed predisposition: urate stones are most common in Dalmatians; silica stones in German Shepherds; calcium oxalate in Miniature Schnauzers, Bichon Frises, Lhasa Apsos, Yorkshire Terriers, Shih Tzus, and Miniature Poodles.
- Urinary tract infection (UTI): many bacterial infections make the urine more alkaline and thus favor the formation of struvite stones. Additionally, the bacteria can act as a nidus for stone formation
- Increased stress levels can also contribute to urolith formation.
The severity of signs depends on the location of the build up and can include:
- Frequent urination but in small amounts
- Painful urination (crying) and straining
- Blood in urine
- Maintaining urinating posture for longer periods than usual
- Dribbling of urine
- Restlessness and discomfort
- Licking the genital area frequently
- In advanced cases, vomiting and decreased appetite
Get Advice from Your Veterinarian
If you notice any of the changes above, consult a vet as soon as possible. The over-accumulation of urine can cause the bladder to become tense which may cause it to rupture, discharging its contents into the abdomen and causing the animal to go into shock condition. However, if urolithiasis is caught early, medical and therapeutic diet management can be leveraged to dissolve the crystals. Also, to relieve the pressure, a vet can empty the contents of the bladder either by passing a urinary catheter (tube) or with the help of a syringe (cystocentesis). In case of bacterial infections, antibiotics are prescribed along with urinary acidifiers to hinder further stone formation. In some cases, a lifelong change in diet may be needed to prevent the stones from forming a second time.
If the stones are lined up in the ureters then retrograde hydropropulsion can be used in male dogs. This involves a saline-filled syringe being pushed in to inject fluid at high pressure to move the stones from urethra to bladder.
If the stones can’t be removed medically then surgical intervention is necessary. Surgical removal is performed depending on the location of the stones – a cystotomy for the bladder, urethrotomy for the urethra and a nephrotomy for the kidneys. The prognosis for urethral stones and kidney stones is less favorable than the prognosis for urinary bladder stones.
Advanced techniques like lithotripsy can be used to break down big stones with the help of ultrasonic waves so that they are flushed out in the urine easily, without blocking the tract.
- High water intake will help dilute the urine – always ensure your dog’s water bowl is full
- Avoid high protein diets. Instead provide a balanced diet, with guidance from your vet.
Urinary stones have high recurrence rate. Your vet will provide your pet specific diet recommendations to lower the risk in future.