I have 2 sows aged around 14-16 months who have been together happily with just the occasional spat until about 6-8 weeks ago. The younger one (Cookie) started to display increasingly dominant behaviour. She does it all from rumble strutting to mounting & it gets very noisy at times! It doesn't look like any blood has been drawn but I am getting concerned about the length of time this has gone on for & any long term effect it might have on the older piggie (Charlotte) being chased & mounted so much. I have read that it is common around this age for piggies to challenge hierarchy & to leave them to it but is it common for it to go on this long? They have quite a big cage & run free around the front room whenever someone is here to get them out.