Uterine Blockage

 A friend's cat has been going through exactly the same as Luther, so that's the third I've heard of in a short time. Male cats are more prone to urinary blockages than females because their urethra is longer and narrower than that of females, making it more susceptible to blockages. Here's hoping little Tommy makes a full recovery but I would like to know what is the cause of it? Is it something we are feeding them? I know cats should have plenty of wet food as dry can cause problems, but some cats, Luther being one of them, will leave the wet food for the dry!