Urinary problems

Yesterday, my male kitty Woody (almost 2 years old and neutered) urinated outside of the litter box. One of the dogs was near the litter box so I just figured that Woody was avoiding it because of the dog. But then this morning, he squated five different times in various places in the house. Not much came out, but it was bloody each time.
So I took him to the vet as soon as the vet opened this morning. The vet said that he has crystals which are blocking him from urinating properly. He said something about a "sand problem". He gave Woody a shot of Gentocin and Penicillin and put him on Amoxicillin (25 mg., 1 dropper three times daily) and Uroeze (200 mg., 1 tablet twice daily). He also recommended a special diet which helps with this problem.
The vet didn't explain a whole lot about the problem. Does anyone have kitties with this problem that may be able to give me some more information about it? Thanks!

Crystals are formed when the PH of an animals urine is to acidic or to alkaline (each creates different crystals). These crystals can cause a blockage in the urethra making it so the cat can't pee properly, and in some cases lead to bladder or even kidney stones. The special food is used to make the PH of the urine more in the middle of acidic and alkaline. The only thing I can think of when a vet says a "sand problem" is when I have done a urinalysis is sometimes you see this kind of sludge on the slide which is a mixture of bacteria, epithelial cell, blood cells, and crystal fragments.

Urinary blockages are becoming more common, unfortunately. Though most people worry about them occuring in neutered males, they can occur in females too.

Dry food is suspected of contributing to urinary problems. One of my feral cats had a urinary infection with evidence of crystals starting to form. My vet advised me to discontinue dry food and keep him on a high quality canned food. You want to keep as much water in the system as possible, and dry food soaks up water like a sponge.

Catlover, you did the best thing by getting your cat into the vet ASAP. Blockages left untreated are life-threatening. Unfortunately, once cats get this problem it can recur, so continue to watch your cat carefully.