Importance of Urine pH and the Use of Acidic Foods

Myrna’s blood pH was normal at 7.38 (range 7.24-7.40).  Knowing blood pH helps to determine if renal tubular acidosis is involved. Renal tubular acidosis is a symptom of a decline in kidney function. It occurs when the blood pH is too low and the urine pH is too high.  This is caused by the kidney’s inability to either keep enough bicarb in the body or to excrete enough acid in the urine.  On the blood work, you’ll also see a drop in bicarb if a cat has renal tubular acidosis.  A cat will also drink too much and urinate often but that also mirrors the actions of a cat like Myrna that takes heart meds which promote drinking and excretion.  However, not only is Myrna’s blood pH normal, but her bicarb level and urine pH are also normal.

Urine pH can be high for other reasons and can lead to the formation of crystals in the urine.  Crystal formation isn’t a sign of kidney disease but can lead to blockage in male cats and might irritate the bladder and lead to infection in female cats, causing the cat to urinate out of the box and to possibly have blood appear in the urine.  A high urine pH is best avoided for these reasons.  Cats prone to crystals or UTIs often eat acidified foods like Royal Canin’s So or Hill’s CD.  However, for cats which might possibly develop kidney disease or which have kidney disease, the vet said it is best that they avoid eating these bladder specific foods such as SO. It’s because the foods, in order to entice the cat to drink more water-water is needed to aid the bladder to flush out crystals and any bacteria, and hydration is necessary for kidney function in general-these foods add a lot of sodium and high levels of sodium are to be avoided for cats with kidney disease or which are in danger of developing kidney disease.  So, the MSU vet suggested we take Myrna off of SO, which she was given by her regular vet to combat crystals she had a few months ago and to combat a possible reason for urinating out of the box (back before the Valium she takes for litter box issues had begun to work.)  They suggested we switch to Hill’s CD but also find another low sodium food she might like.  In Myrna’s case, the issue is a two edged sword: she needs to drink a lot to stay hydrated since her heart meds encourage excretion of fluids; staying hydrated helps her kidneys; and yet she needs to cut back on the sodium in order to eliminate one cause of kidney disease and therefore, needs to stop eating SO.  If she stops eating SO, will she also stop drinking enough water to remain well hydrated and run the risk of being dehydrated, leading to formation of crystals again or issues with bodily dehydration in general?  We’ve decided to feed her wet CD mixed with a bit of SO.  She needs to drink enough water but perhaps not so much that she urinates every 2 hours.