This site has been so helpful for years and it's so much worth reading I'd like to put a grain of sand for those who are helpless -and terrified- seeing a cat with urinary blockage, especially when vets can do so little that they put mine through 4 catherizations (only to make matters worse) and then surgery for absolutely nothing. Only God knows how I stumbled upon Cantharis, the 6c dose, by Boiron. My little one is alive because of this. It may take a couple of days if it's been ongoing, maybe less. If he doesn't want to lick the 3 or 4 small pebbles I syringe them, first diluted in a tiny bit of spring or filtered water, or sometimes he'll lick the water-diluted little pebbles adding a tad of chicken baby food. 1st time depending on how bad the blockage I've given it twice in 3 or 4 hrs., then another couple of times during the day more or less according to progress. Has to be given on an empty stomach and with no less than 30 to 45 min. clear of any feedings, before or after. This is only to be given for a few days, so looking for everyday help, I'll try the ACV. Thanks.