Therapeutic Effects of Parenteral Vitamin C (Ascorbic Acid) on Struvite Crystalluria in Domestic Male Cats

BACKGROUND:  Struvite crystals (Magnesium Ammonium Phosphate) are one of the most common causes of urolith formation in cats. Presence of these crystals in urea leads to urinary obstruction and idiopathic cystitis. The prevalence of urinary crystals has increased in recent years, thus there has been a growing interest in development of noninvasive, fast responsive therapies. Vitamin C is a safe compound with antioxidant properties. This vitamin is known as urine acidifier as well. Since struvite crystals are more soluble in acidic pH, it could be expected that vitamin C application could improve crystals dissolution as well as their disposal. It could also prevent other complications. OBJECTIVES: This study was designed to analyze the effects of vitamin C in reducing the rate and intensity of struvite crystals with current long term therapies such as diet alteration, acidifier’s applications and diuretics. METHODS: Ten male domestic cats with clinical signs of lower urinary tract disease were selected. Struvite crystalluria was confirmed by urine analysis and ultrasonography. Cats were divided to treatment and control groups each containing 5 cats. Both groups were treated by conventional therapies for two weeks, however, during the 1st week the treatment group received injectable vitamin C (100 mg/kg, every 24h, SC) and the control group received oral DL Methionine (200mg/cat, every 8h), in addition to conventional therapies. Urine was collected at days 0, 7 and 14 and its pH, specific gravity and number of crystals were calculated. Presence of floating echogenic foci was evaluated using ultrasound. RESULTS: Significant decrease in struvite crystalluria was observed in both groups. However, in group treated by vitamin C this decrease was faster and more effective. In addition, in case of obstruction, vitamin C showed better therapeutic effects. CONCLUSIONS: According to these results, vitamin C injection could be a therapeutic approach in treatment of urinary tract obstructions where fast response is needed to avoid further complications. Oral methionine seems to be a suitable choice for prophylaxis in patients with moderated signs and relatively high urine pH or continuing therapy to prevent recurrence of disease.