Effect of a struvite dissolution diet in cats with naturally occurring struvite urolithiasis

Abstract

Objectives The aim of the study was to determine the efficacy of the low struvite relative supersaturation diet in dissolution of feline struvite cystoliths. Methods This was a prospective, open-label, two-center study. Twelve client-owned cats were enrolled based on the radiographic appearance of their uroliths and urinalysis parameters. Cats were fed the test diet exclusively for up to 56 days. Cats were radiographed every other week until radiographic evidence of dissolution occurred or the end of the study period was reached. Cats with radiographically apparent uroliths at the end of the study period underwent cystotomy for stone retrieval and analysis. Results Nine of the 12 cats completed the study. Eight experienced radiographic dissolution; seven of these had complete dissolution within the first month of treatment. One cat, whose owner declined cystotomy after partial dissolution at day 56, had complete radiographic resolution at 70 days of treatment. Two calcium oxalate urolith cores were removed from a cat that had partial radiographic dissolution. Conclusions and relevance The test diet was successful in dissolving suspected struvite cystoliths. As this diet is suitable for maintenance feeding of adult cats, it may be a suitable choice for long-term prevention of feline struvite urolithiasis.

Urolithiasis in cats: Evaluation of trends in urolith composition and risk factors (2005‐2018)

“…The low proportion of positive struvite-containing urolith cultures is similar to a prior study 6 and consistent with this mineral type most often being sterile in cats rather than infection-associated, as typically noted in dogs. 6,19 Because the most common bacteria cultured were Staphylococcus spp., struvitecontaining uroliths in cats can be infection-associated. Interpretation of urolith cultures should be tailored to the individual patient and antimicrobials often are not warranted if clinical signs are no longer present after the urolith is removed.…”

“…Moreover, studies evaluating struvite dissolution protocols in cats reported no apatite mineral content in the uroliths from the majority of nonresponders; apatite content in responders cannot be evaluated. [17][18][19] Our data suggest that further education regarding noninvasive treatment for suspected struvite urolithiasis is needed to promote dietary dissolution as the first therapeutic approach. 21 If dietary treatment fails, urolith removal and accurate histories should help elucidate reasons for failure.…”

“…With newer renal decompressive procedures in which ureteral stents and subcutaneous ureteral bypass systems are placed without ureterolith removal, 4,5 a decrease in the proportion of CaOx‐ and DSB‐containing uroliths removed from the upper tract likely has occurred, despite the disease still being prevalent. It is unknown whether cats in our study with CaOx‐containing and DSB‐containing uroliths submitted from the lower urinary tract also had these uroliths in the upper urinary tract that were not removed because this information is not captured on the submission form, and removal of upper urinary tract uroliths is not recommended unless clinical abnormalities such as ureteral obstruction or perceived patient pain are identified 19 . Based on the overall proportion removed from the upper urinary tract, it is unlikely that the decrease in the proportion of CaOx‐containing urolith submissions is solely because of the lack of removal of upper urinary tract uroliths.…”

Case Report: Application and Limitations of a Plant-Based Diet Formulated for a Cat With Feline Lower Urinary Tract Disease

“…Firstly, controlling intake, and thus, to a degree, excretion of precursor minerals can reduce the substrate for crystal formation (30). The contribution of urinary protein to struvite crystalluria has been less commonly reported but demonstrated in vitro, making consideration of dietary protein levels warranted to reduce protein excretion (31).…”

“…The presence of ammonia and a pH > 6.0 are required for precipitation to occur, as high urinary pH reduces the solubility of phosphorus and magnesium in the urine, allowing the ammonia to bind the minerals leading to precipitation as struvite crystals (29,31). Manipulation of the urinary pH to maintain a slightly acidic (pH < 6.5) environment thus increases solubility of struvite, reducing crystal precipitation (30,32). Urine pH can be manipulated by inclusion of acidic sulfur-containing amino acids and minerals such as phosphorus, chloride and sulfur, and restriction of basic minerals, such as calcium, magnesium, sodium, and potassium.…”