Is there some genetic connection to altered hormone production that would cause hens to grow spurs, yet lay eggs normally, have normal combs, wattles and plumage, and not crow? I'm curious about how something that is usually a secondary sex characteristic would pop up as a natural condition, without having hormones involved in some way. Also, is it possible that the condition is congenital (developmental in the embryo/egg) -- maybe due to the mother having some hormonal abnormality that is passed on to the chicks and affects their development, including post-hatch growth?
I had a RIR hen with HUGE spurs. almost 2" long. She was a "rescue" from a raccoon attack, and I was told by the woman I adopted her from that the hen had not laid any eggs since being injured though she recovered from the injuries. She also had a large comb and wattles (larger than a usual RIR hen). But she never crowed. I do think that it was a hormonal issue -- not genetic or congenital -- caused either directly or indirectly by the injuries. I've never had "hormonally normal" hens that naturally grew spurs, though.