What are common myths about pet aging?

Top myths: 1) '× 7 formula' (wrong, see epigenetic), 2) 'cats have 9 lives' (folklore), 3) 'big dogs live shorter' (true, but not by years × 7), 4) 'older pets can't learn' (false, but learning is slower), 5) 'pets feel age the same as humans' (different sensory experience).