I don't have any experience with cats and crystals/urinary infections, and I am not a vet, but maybe a holistic food would help. I feed my cats, 2 female, 1 male, Holistic Blend which I buy a our local Health n' Harmony store. It is also available at Superstore, Loblaws, and it's ingredients are
Does Have
chicken meat
brown rice
barley
millet
salmon
amaranth
alfalfa
rosemary
garlic
cranberries(which is good for urine)
apples
cinnamon
soy protein
flax seed
dried whole eggs
yeast culture
vitamin A acetate,D3,E, B12
folic acid
zinc
niacin
Does Not Have:
animal by product
BHT
BHA
Ethoxyquin
corn
wheat
sugar
salt
beet pulp
growth hormones
antibiotics
I stimulates the breakdown of ammonia in the digestive system to reduce stool and urine odour. Reduces urinary ph and provides low dietary magnesium.
It is for all life stages. :You can research it at
www.holisticblend.com.:)