Struvite stones are disolvable with diet - calcium oxalate are NOT. However, surgery is recommended for both:
Struvite stone can be removed surgically, removed with a special technique called "voiding urohydropropulsion," or dissolved via diet.
Surgical removal is the most direct method of removal. The advantage is that the stones are removed and healing may commence all in one day. The chief disadvantages are those inherent to surgery: anesthetic risks, post-operative pain, risk of contaminating the abdomen with infected urine, possibility that not all stones will be removed, possibility that the bladder stitches will not properly hold. These risks are generally considered minor and complications associated with "cystotomy" (opening of the urinary bladder) are very unusual.
If the stones present are small enough to pass, the bladder can be manipulated in a way to promote expulsion of the stone through the urethra. This is called "voiding urohydropropulsion" and involves filling the bladder, agitating the bladder so the stones float freely in the urine, and then generating a high pressure urine stream to force the stones out. This technique only works if the stones are small and if there are numerous stones present, often several attempts are needed if this is to be the only means of removal. Often this technique is used to obtain a sample stone for analysis to determine if dietary dissolution is feasible.
Dietary dissolution of the stone is possible with struvite bladder stones. A special food called S/D diet® is made by Hills for the specific purpose of dissolving struvite stones. The food is of a gel-like consistency and may not be palatable to the animal but if dietary dissolution is attempted, S/D must be the only food fed to the dog during the period of dissolution. Antibiotics are needed as long as stones are present in the bladder (bacteria are encrusted within the stone and as the stone dissolves, they are released). On the average, 3 and a half months are needed to dissolve the stone but the diet should be continued for a full month after the stones are no longer visible on radiographs because small stones may be present but not large enough to see. Radiographs are taken monthly to monitor progress. S/D diet is not meant to be continued as a regular diet after the stone has been dissolved; Hills recommends not feeding S/D diet any longer than 6 months. Aside from the long treatment time, an important disadvantage of this approach is the possibility of urinary tract obstruction as the stone gets smaller and an unsuccessful attempt to pass the stone occurs. This is potentially a life-threatening hazard for male dogs as they possess the narrow urethra.
S/D diet is very high in fat and high in salt. It should not be fed to patients at risk for pancreatitis, patients with heart disease, kidney insufficiency, or high blood pressure.
This is feline but the same premise:
Talk with your vet about the options and please let me know how your boy is doing.
Sincerest best wishes,