Vet at FirstVet answers:
The most important thing to do is to find out if your cat CAN urinate, that is, to ensure there are new spots of urine in the litter tray after your cat has just used it.
If your cat is only passing a few drops of urine, or none at all, you MUST seek veterinary care immediately. A cat that cannot urinate is at risk of dying. The urinary bladder can also burst, which is life threatening. If you are unsure whether your cat is able to urinate you should seek veterinary care. You should never risk waiting to see if your cat can urinate later on in the day. Blocked bladders are more common in male cats due to the shape of their urethras.
If your cat is able to urinate but only has a little bit of blood in its urine and otherwise seems fine you should still seek veterinary care within one day. It is, however, not as dangerous as a blocked bladder. If, on the other hand, your cat seems a little slow, off, has a fever, does not want to eat, or if there is a lot of blood in the urine you must seek emergency veterinary care. Most cats with blood in their urine do not have a urinary tract infection. Rather, their urinary tract is inflamed as a result of stress, urinary stones, etc./nbsp;