Urolithiasis Signs, Causes and Treatment
Urolithiasis is a disease which results from formation of stones (calculi or uroliths) in the urinary tract. Crystals form in urine when the concentration of its constituents exceed a critical level of saturation. Dietary factors can profoundly influence urolith formation because dietary ingredients and feeding patterns influence the pH (a symbol denoting acidity), volume and concentration of the urine.
Traditionally, struvite urolithiasis has been of greatest concern, but calcium oxalate urolithiasis is now seen with increased frequency. Uroliths which are commonly found in dogs include struvite (magnesium ammonium phosphate), calcium oxalate, cystine and ammonium urate. Mixed calculi can also occur in some cases.
STRUVITE In dogs, struvite urolithiasis is often associated with urinary tract infection. Bacteria create an increasingly alkaline environment and conditions which are ideal for the formation of struvite. Where infection is present, prolonged antibiotic treatment is necessary in addition to dietary and other measures. Dietary protein restriction may also be beneficial in these cases.
CALCIUM OXALATE It is not possible to dissolve calcium oxalate through diet and other means, and surgery is currently the only method of removing them in dogs. However, dietary changes can help to prevent recurrence of the condition. The goal is to reduce urinary saturation with calcium oxalate. These diets should promote increased urine volume, preferably through the addition of water to the food.
CYSTINE Cystine occurs in dogs with an inherited defect in cystine (a component of many proteins) metabolism., resulting in cystinuria (presence of cystine in the urine). This leads to cystine urolith formation, since cystine is relatively insoluble, particularly in acidic urine. Dissolution and prevention of recurrence of cystine uroliths can be achieved through:
- Increased water intake to increase urine volume
- Reduction of dietary cystine to reduce cystine excretion
- Alkalinisation of urine (with bicarbonate or citrate) to increase cystine solubility
- Administration of compounds such as D-penicillamine or 2-mercaptopropionylglycine (2-MPG), which convert cystine to a more soluble compound.
AMMONIUM URATE
Ammonium urate uroliths occur mostly in Dalmatians and in dogs with portosystemic shunts when conversion of uric acid to allantoin in the liver is impaired. Increased urinary excretion of uric acid may predispose the dog to urolith formation.
Surgical relief of obstruction may be required in some cases. In others, dissolution and prevention of recurrence of uroliths can be achieved through:
- Restriction of dietary protein
- Supplementation with potassium citrate to promote neutral or slightly alkaline urine
- Increased water intake
- Administration of allopurinol which decreases uric acid production.
More information: Urinary (Bladder) Stones in Dogs - Treatment, Special Diets and Prevention
Dog breeds that are predisposed to Urolithiasis
References:
1. Veterinary Nursing by D. R. Lane
Go Pets America recommends seeking the advice of your local veterinarian for the most appropriate vaccination program and for the diagnosis and treatment of your pet's health problems. For vaccination requirements please contact your state and local licensing authorities.
|