My dog who recently died of old age used to get these I'm not sure what it's called, he would pee blood and we found out that if you give your dog pedialyte about every 30 minutes, you can make it go away, it happened to my dog about 5 times, and they all happened when the vet was closed, so thats the best thing you can give your dog if he's peeing blood and the vet is closed because that disease (whatever its called) is really deadly. I hope that helped. :)

Ps- the pedialyte bottle looks like this:
http://www.bebein.com/site/GoodsImg/Pedialyte-LiquidGrape-1_6.jpg
It's usually found in the baby section.