Why is my cat scooting and streaking blood after defecating?

by Natalie
(UK)

Our 3-year-old male, non-pedigree cat has a problem which is driving us crackers. Every time he defecates, he scoots along the carpet leaving streaks of fresh blood.

It started with yellow streaks around June last year (presumably anal gland secretions) but within weeks progressed to blood.

So far we have tried a high fiber diet, a low fiber diet, a wet only diet, a dry only diet, a fresh chicken and fish diet (cooked) and he is now on a special sensitive anti-allergy hydrolyzed protein dry diet.

None of these changes have made a difference.

He has had his anal glands checked many times. There has never been an issue. He has had fecal samples taken and several blood tests (including for leukemia).

The only blood abnormality has been elevated B12 which then normalized. His fecal screen was clear, but he was given a 5-day, broad spectrum course of antiparasitics just in case.

He spent five days as an in-patient at a university veterinary school based center of feline excellence. He was examined extensively under anesthetic and he had a colonoscopy which showed an area of inflammation a little way up his rectum.

This was biopsied and everything came up negative - it just showed some inflammatory markers. His anus looks healthy and has no tears and does not bleed from here.

A few weeks ago, we finished a prolonged course of oral steroids which were to rule out more unusual types of IBD.

Nothing that we have done has helped in any way. He looks well, his coat is shiny and he has not lost weight. The only changes have been mild signs of anxiety, but he has been messed around with rather a lot.

If we manage to catch him in the litter tray, we always wipe his bum. The paper is usually clean but when we put him down he scoots and there is the blood!

There is only occasionally signs of blood in/on the stools and it is always fresh. Other than when his food has been messed around with, his stools have been consistently well formed and always done in the litter tray.

As a side note, he has had unexplained diarrhea for the last 48 hours (4 x yesterday, 2 x today).

He is a house cat so we can rule out lots of environmental factors (although he did spend a week in a cattery around the time that this all started).

Any fresh ideas/suggestions would be most welcome as we are currently hitting our head against an expensive brick wall!

(Please note that his case is ongoing, we have not given up. But, as the experts have run out of ideas we are clutching at straws and hoping that somebody somewhere has had an experience similar and can help to shed some light. He is not presenting typically - or in fact atypically - for anything).
Thanks.