Which prescription food for cat - urinary vs. kidney

[Siaynarr]

My neutered male Manx/Siamese cat is 11 years old and 13 lbs. He has a history of urinary crystals and has been on a urinary prescription diet for at least five years. I've also been adding water to his wet food to make sure things stay flushed because he's had a blockage three times.

Recently he's been drinking more water than usual so I bought him into the vet and the blood work showed that he has kidney disease. The vet has recommended switching him to a prescription food for kidney health, but I'm worried that he still needs the urinary diet to avoid crystals. My question is if that's a valid worry, or if having dilute urine from all the water intake will be enough to avoid blockages.

And one more question - I bought a ferret, does cat food good for ferrets? I found few examples on this page TIA!

[Mollycat]

Personally I would go with the vet on this one, depending how bad his kidney readings are and how high the risk of crystals is.

The irony is cats aren't the same as us and although fluid is good and they need to be hydrated, too much water is also bad. In our case and theirs, we also need the right balance of electrolytes to use that water to hydrate at cellular level. In their case the need for fluid is much lower than ours as they get nearly enough moisture from their wet food with very little need to drink. Too much water can lead to diluted urine, and cats' urine should be quite strongly acidic to prevent, you guessed it, crystals.

[Kay]

I'd trust the vet on this one too - urinary crystals and kidney disease are both very common in cats, and every vet should be experienced in treating both.