Dr. Dan Christian specializes in small animal medicine, with special interests in behavior and nutrition. He has been instrumental in establishing animal behavior residencies for veterinarians at leading veterinary schools and developing innovative programs with veterinary organizations in the United States. He is a member of the American Veterinary Medical Association, the American Animal Hospital Association, and the Southern California Veterinary Medical Association. During his professional career, Dr. Christian earned the American Association of Feline Practitioners Award. He has also appeared as a guest on television and radio pet health programs nationwide, and to has authored numerous articles for pet health magazines.

Q: I have a five-year-old female Persian who chronically gets urinary tract infections. My vet puts her on a course of antibiotics and it seems to clear up, but two or three weeks later it's back. She urinates quite a lot at a time, but there is blood in her urine. About five months ago it cleared up for about three months, but it recently came back and this time the antibiotics don't seem to be clearing it up. She was on a special struvite formula veterinary diet, but it doesn't seem to work, as she still chronically gets infections. I have thought of switching her over on to canned wet food and/or a raw meat diet, but am not sure whether this will solve my problem.

A: It sounds as if you need to have a little more diagnostic work done for your cat. Some additional tests may help determine why the condition is so resistant to antibiotics and a veterinary diet.

When cats develop lower urinary tract infections, the crystals (or stones, in more advanced cases) in the urinary bladder are generally composed of struvite or oxalate material. These two types of crystals or stones are treated in completely different ways. The struvite stones improve in an acidic environment, and oxalates respond to the opposite alkaline environment in the urine. A urine culture and sensitivity test will go a long way in determining which treatment regimen to pursue. If stones are present, surgery may be considered to remove them, as they can be resistant to conservative treatments at times. Ultrasound may also reveal a hidden reason why the condition is persistent.

Feeding wet food alone is a good choice, but may not resolve the problem on its own. Wet food has good moisture levels (which is good for cats with bladder infections) and also ideal levels of protein and other essential nutrients, so it is a good base from which to work. But I encourage you to go with additional tests from your veterinarian to get to the exact cause of the infection.