Q: My vet recently found that my Sheltie’s urine has an abnormally high pH. She is on a prescription kibble diet, but the ingredients don’t look very good. Should I switch her back to her regular freeze-dried raw diet?

A: The most likely culprits of alkaline urine are struvite stones (or crystals) and urinary tract infections. Carnivores that eat a good amount of red meat in their diets naturally produce acidic urine (around pH 4 to 6), which prevents crystal formation. Red meat contains 60 to 70 percent water, and assists in preventing dehydration and excessively concentrated urine. Most commercial pet foods contain high levels of nonmeat ingredients, as quality red meat proteins are expensive. Ingredients used in their place—like meat by-products and white meats—do not have the same acidifying effect. Another potential issue is urease-splitting bacteria that can grow in the bladder and split urea molecules into nitrogen, which is ammonia-based and causes the pH to rise and remain high. Active signs of cystitis (bladder infection) include blood in the urine, and frequent, painful urination of small amounts.

Your prescription diet likely includes artificial acidifiers. However, you can achieve the same effect naturally by simply opting for red meats. I also advise using additional vitamin C, but be sure to use true ascorbic acid, and not a buffered version like sodium ascorbate (which has no pH-lowering effect). Cranberry tablets also contain high levels of natural vitamin C, and create a mucilaginous lining on the mucosal surface of the bladder wall, thus inhibiting the attachment of bacteria on it and assisting the voiding of any contaminants (like crystals) with normal urination. You may add about 1 to 2g of vitamin C powder and 1,000mg of cranberry tablets per day for a medium-sized (15kg) dog. I suggest feeding about 70 to 80 percent red meat (like lamb or beef) in each meal, making the vegetable/ carbohydrate component only 20 to 30 percent (by weight/volume). Do check the freeze-dried diet you have been using to assess how much meat protein it contains, and if the main ingredient is red meat. White meat like chicken and tripe are unsuitable for your dog. 

Ideally, you should have your Sheltie’s urine tested for pH every month for the next three to four months to make sure it is acidic. You may also do this weekly at home using a pH test strip. The ideal pH is about 5 to 6 for a dog. Once the pH is stable, you can stop feeding the cranberry supplement, and check her pH levels again a month later.