Why does my dog have a fleshy lump at its anus?

A lump of flesh at the dog’s anus may come from rectal prolapse or other anal disease. Take the dog to a vet for detailed clinical and lab exams, possibly anal examination, X-ray, and ultrasound to confirm.

Rectal prolapse means the rectal lining pushes out or fully turns inside out, showing a long cylindrical protrusion with red, swollen mucosa, repeated straining, floor rubbing, and only watery stool. Prolonged prolapse turns dark red to black and can ulcerate or necrose, needing prompt surgery, good nutrition, rest, and hygiene.