Originally Posted by sharky
How since both types need slightly different therepies??
Although it sounds counter-intuitive that a food could prevent both types of crystals, i.e., one that develops in pH basic conditions (struvite/magnesium ammonium phosphate) and one that develops in pH acidic conditions (calcium oxalate), one of the main reasons Royal Canin Urinary S/O is formulated to prevent the occurrence of both types of crystals is because of RSS methodology. To make a long complicated story short, RSS methodology predicts the crystallization of urine. Under conditions where the RSS < 1 (undersaturated), stuvite crystals will not form, and under conditions where RSS < 12 (metastable) calcium oxalate crystals will not form. Royal Canin Urinary SO is formulated to produce urine in cats that meet these requirements and therefore, this food can be labelled for management of cats with struvite or calcium oxalate urolithasis. RSS methodology sounds pretty theoretical at first glance, however, published feeding trials have shown that these principles hold true in vivo. The presence of DL-methionine (as an acidifier) and sodium chloride (salt) in the dry food also contributes to increased water uptake and urine dilution. From what I've read in the literature, RSS methodology is only one of many factors that contribute to urinary pH.Right from the Waltham's website (the PDF in one of my other posts):http://www.walthamusa.com/Learning%20Center/SO30.html
Ten years ago, the majority of uroliths removed from cats were struvite (magnesium ammonium phosphate). Since struvite formation is highly dependent on urine pH, diets designed for managing struvite uroliths encouraged the production of severely acidic urine and were highly restricted in magnesium.
In the past ten years, there has been an increase in the incidence of calcium oxalate urolithiasis. The dietary management tools for struvite (acidification and severe magnesium restriction) have been suggested to be risk factors for calcium oxalate urolith formation.
The management of calcium oxalate urolithiasis is far more challenging than struvite urolithiasis. In humans, calcium oxalate uroliths can form in urine across the full range of normal pH values (4.8-7.4). Urine pH manipulation cannot be used to reliably manage calcium oxalate urolithiasis, nor is the restriction of dietary calcium and oxalate effective in preventing oxalate urolith formation.
Diets specifically designed to prevent one type of urolith may greatly increase the risk of the other type of urolith forming. Waltham Science has taken a safer approach and invested years of research in developing a single diet which effectively reduces the risks for both types of uroliths simultaneously.
URINARY SO 30TM/MC (dry) and URINARY SO IN GELTM/MC (canned) are the first and only diets which have been clinically proven to reduce the risk of both struvite and calcium oxalate urolithiasis.
Urine Evaluation Using RSS:
The desire to develop diets which effectively manage both struvite and calcium oxalate urolithiasis in pets led Waltham to explore complex research methods for predicting urolithiasis risk in dogs and cats.
The predominant urolith in humans is calcium oxalate and more than 30 years ago, human urologists began looking at ways of predicting the risk of calcium oxalate formation in human patients.
The result was the development of a research methodology known as RSS or Relative SuperSaturation. This methodology involves the analysis of 12 constituents of a collected urine sample, as well as the determination of its pH. These data are then analyzed using a computer program that calculates the concentrations of the large number of possible interactive complexes between all ions present in this urine.
Finally, the program calculates the activity product of the urine sample for a given urolith and divides this number by the known constant thermodynamic solubility product for that urolith to determine RSS. If the sample’s activity product is less than the constant, then RSS < 1.0 and the urine is said to be "undersaturated" for that urolith.
Using RSS to assess the risk of struvite urolith formation in cats:
If a diet has an RSS for STRUVITE of:
The urine produced by cats fed that diet is said to be:
And the risk for STRUVITE urolith formation is:
Less than 1 (Undersaturated)
New struvite uroliths will not form, existing struvite uroliths will dissolve
Between 1 and 2.5 (Metastable)
New struvite uroliths will not form
Any existing struvite uroliths will not dissolve and may grow
Over 2.5 (Oversaturated)
New struvite uroliths may form
Any existing struvite uroliths will grow
Using RSS to assess the risk of calcium oxalate urolith formation in cats:
If a diet has an RSS for calcium oxalate of:
Less than 1 (undersaturated)
New calcium oxalate uroliths will not form
Existing calcium oxalate uroliths will not grow
Between 1 and 12 (Metastable)
New calcium oxalate uroliths will not form
Any existing calcium oxalate uroliths may grow
Over 12 (Oversaturated)
New calcium oxalate uroliths may form
Any existing calcium oxalate uroliths will grow
URINARY SOTM/MC IN GEL (canned) and URINARY SO 30TM/MC (dry) are the first and only diets which have been clinically proven to aid in the management of both struvite and calcium oxalate urolithiasis in cats.
A clinical study examined the recurrence of signs of lower urinary tract disease in 54 client-owned cats with idiopathic (or interstitial) cystitis. Recurrence rate for the year prior to the beginning of the study was 96%, with 52 cats having had at least one episode of LUTD signs in the previous year.
Signs did not recur in 89% of cats fed URINARY SOTM/MC IN GEL in canned format, while 61% of cats fed the URINARY SO 30TM/MC in dry format did not have a recurrence of signs over the 12 month trial period.
The proportion of cats in which clinical signs recurred was significantly lower in the canned diet group than in the dry group. Canned URINARY SOTM/MC IN GEL is the only diet proven to be beneficial in the management of feline idiopathic cystitis."