I take it that you mean Urinary Tract Infections?
They are caused by bacteria. Due to a low acidity in the urinary tract, the bacteria are not automatically killed and can therefore start causing problems.
Apple cider vinegar ( 1 teaspoon in a small bowl of water) and cranberries can help here. Also, feeding raw with as little carbs (grains, rice, potatoes) as possible, is good.
If you don't feel like feeding raw, find a kibble with the least carbs in it. Especially NO potatoes, corn or other grains. Rice is preferrable above any of these, as it has a lower GI.
When I got my girl, she suffered from UTI. Since I switched her to a completely raw meal, the problem has disapeared. She never needed the vet's antibiotics.
Beau 5-7-1994 11-10-2006: Miss you, big guy