Why can't my 8 year old staffy who is perfectly well can't jump onto the settee today but was fine yesterday?

There could be several reasons why your 8-year-old staffy is having difficulty jumping onto the settee today. It may be experiencing temporary discomfort or stiffness due to muscle strain, Arthritis, or joint issues, which are common in older dogs. It's also possible that it has a minor injury or is feeling unwell in some way. If the issue persists or if your dog shows signs of pain or distress, it's best to consult a veterinarian for a thorough evaluation.