Blood on anus

Hello, my parents' 10 year old male ginger British short hair cat just had a small amount of bright red blood coming from his anus. He seems fine in himself, except since they got him 5 months ago from a shelter, he has overgroomed. The shelter sent my parents his vet records when they adopted him, which says he has been overgrooming since June 2021, and it was noted that it was likely stress that triggered it since the owners had just moved house. It says he was overgrooming on his abdomen. When my parents adopted him in May 2022, his abdomen was completely bald, along with the base of his tail, around his anus and the insides of his back legs. The fur on his abdomen has since grown back, but he is still grooming on the base of his tail, around the anus, and now occasionally on his back. This includes him biting the areas sometimes, as well as licking. He also scratches his ears sometimes. We believed the grooming was due to stress, since he is a nervous cat, but now worried the blood could be related. He also has kidney disease, we believe early stage 2. He was eating dry renal food while at the shelter. My parents tried him on the renal wet food, but he didn't like it, and was sick when he did eat it. My mum rang the shelter, and they said that he could eat normal food if Ipakitine was added to it (Although, on his vet notes, his phosphorous was in the normal range when he had a blood test in February 2022) So my mum has been feeding him Sheba, with one heaped scoop of Ipakitine added, plus some water added to his food to help with hydration for the kidney disease. He isn't being sick or had diarrhoea. We couldn't see any visible blood in his faeces when we looked just now, although it is difficult to tell as he covers it up. But he hadn't had diarrhoea. He hasn't been sick, except a couple of weeks ago when my dad got the wrong food by mistake, with jelly instead of gravy. He is a very affectionate cat, but also nervous. He used to run as soon as anyone stood up when my parents first got him, but he has improved a lot recently. He has a good appetite, isn't losing weight, seems fine in himself. But looking back, I have thought before that his anus seemed sort of pink and slightly wet at the opening, but had just assumed it was normal. So I don't know if he has had bleeding before and just cleaned it before we have noticed. He is an indoor cat. My parents are going to take him to the vet very soon, but what could be the possible causes of this? Could the Ipakitine be causing constipation? I couldn't find much information about that. How likely is it to be IBD, if he doesn't have sickness or diarrhoea? How would a vet test for IBD? On his vet records, it says he had a small amount of frank red blood and mucus on semiformed stool when he was 1 year old, and he was treated as for colitis, with a bland diet and parasite treatment, and no more issues like this were noted since then. This time though, he hasn't had mucus or semiformed stool, so I assume this has a different cause. Thank you in advance

Hello!   Causes of finding blood on the anus split neatly into two main groups;  Group 1) is blood that comes from within the anus ie bleeding into the digestive tract.  If it still looks like blood, then it is unlikely to come from the stomach or small intestine, which would look black, so that leaves bleeding into the large intestine or rectum.  Worms can cause this, for example  Group 2) As you suggest, would bleeding to the local skin, often associated with skin disease, allergy, anal glands etc.  More to follow

Number 2) above might fit with the history of skin disease generally;  your cat sounds to be over-grooming in all the sites linked to flea, but also other, allergy.  A first concern might therefore be to remove all possibility of fleas.  Owners always wince when we say this and say 'my cat cant possibly have fleas,' but the truth is that they dont need to *have* fleas to suffer a flea allergy;  there just have to be fleas, or microscopic flea debris, present somewhere they go.   More to follow

A less cited cause of overgrooming is pain or irritation, perhaps associated with constipation or pancreeatits or even wih back pain.  More to follow

So over-grooming can be associated with pain or allergy and when in response to pain, doesn't always occur in the part of the body where the pain is;  more the general direction.  Bleeding can occur with skin disease or intestinal disease in the area.   I have also known cats bleed from their guts due to tumours or indeed, general clotting problems.   A vet would probably try to pinpoint the source of the bleeding, then try to figure out which of several causes they were most likely to be looking at, in order to treat it.   Both skin disease and intestinal disease can progress very quickly and can be exacerbated a lot by stress, so stress control may turn out to be very important.  There are vets writing about this online, for example Sarah Caney - and it can be very important to research, because stress in cats doesnt present as one might expect. I do think that its well worth continuing to work with your GP vet in order to explore these possibilities. I hope that something here might be helpful.

Allow me to wish you the best of luck in making the greatest choice you can for your pet, since your professionals have evaluated the patient and will understand and offer suggestions better than I can from here.