I'd like a second opinion on what to investigate next for this pretty irritating bowel problem.
PROBLEM:
For ~1 year he passes stool anywhere but the litter (floor, sofa, bed, chairs, my pillow, his own sleeping spot...), then runs off with spasms of the tail/anal area, as if in pain. The stool is mostly on the "small and hard" side, but occasionally looks normal. This persisted on an all-wet diet. He regularly pees in the litter, and occasionally will poop there too (hence, there's no dementia issues or arthritis, he squats just fine when peeing, and does it at least a couple of times a day).
The stool often contains fur. He grooms a lot and never vomits hairballs.
Early October: tapeworm segments in the stool, treated with Drontal (praziquantel/pyrantel) and Frontline. The worms were gone within 2 days, but he still goes outside the litter about half the time (yesterday in his own bed). I was hoping the parasite would be cause of the problem but it isn't.
OTHER CONDITIONS:
He was diagnosed with hyperthyroidism and stage 2 CKD in July 2026 and is being treated with thiamazole (Apelka) and benazepril (Fortekor). Both are managed separately, and I'm asking here only about the bowel problem.
TESTS
Earlier work-up with my vet (bloodwork, ultrasound, manual anal gland check) was reported as normal. In the July bloodwork, apart from the thyroid and kidney findings, calcium, electrolytes and CBC were normal.
Abdominal ultrasound, 17 Sept 2026:
Intestinal changes consistent with chronic enteropathy of undetermined nature.
No significant abdominal lymphadenopathy; major vessels normal.
My vet downplays the intestinal finding. And keeps suggesting behavioural issues. We got him a larger litter, but it doesn't help. Besides he uses it every day, to pee, and only that.
TREATMENTS TRIED
Fortiflora every day and Fibrapet (insoluble soy fibre + inulin), on my vet's advice, every day. It's been 3 weeks now but no dramatic improvement. He'll poop in the litter maybe once every 5 times. He refuses all renal prescription foods, but he eats good quality but standard wet food. He is active, playful, always hungry (gained ~700 g over ~6 weeks) when we finally gave up on renal food and went back to his favorite.
My vet's view: mostly litter aversion/pain memory. They advised more litter boxes with pheromones, plus fibre, but to be honest I think that's nonsense.
What would you investigate or try next for the difficult, apparently painful defecation (abdominal X-rays for colon loading, sedated rectal exam, lactulose/macrogol, fuller GI work-up)?
How much weight would you give the ultrasound finding of chronic enteropathy, and would you pursue biopsy or an empirical trial first?
Thanks!