My dog is scratching his butt on the carpet and there are streaks of blood where he has scratched. What is causing this.

Probably has ring worms.
Take him to the vet.

I agree with hkstroud. Sounds like worms. Sadly we can't diagnose online. Time to see a vet. Worms are easy and fairly inexpensive to treat.

Worms! Such a wives tale...

He probably has impacted anal glands that are now infected (which is what explains the blood)

Actually it's not an old wives tale at all.

There are many different types of worms, and one of the reasons that dogs scootch their bums on the floor is worms. So to say that it's definitely not worms, or say that it's a "wives tale", is inaccurate.

Yes, it could very well be impacted anal glands, I've had that issue before with my lab Indy (RIP), he had impacted anal glands frequently, to the point where I learned to express them myself instead of constantly paying the vet to do it. It's nasty, and if done incorrectly it can cause issues.

So, either way, worms or impacted anal glands, or something else, the OP needs to take her dog to the vet. I think we can all at least agree on that. :)

Ok, whatever

Ok, whatever

An answer that leads me to believe that you don't have any info to the contrary? Just had to get the last shot in? :(

I know you're a vet tech, but when it comes to medical issues that I post on on AMHD, I rely on what my vet says. Worms can cause anal itching, and scootching, according to my vet with 30 plus years experience.

If you have documented proof that only impacted anal glands cause scootching, and nothing else, then I'd love to read it. Please post the verified links.