I'm going to add my vote to the "Males appear to have more health problems due to their higher popularity" option. I have had a number of each gender and I have never seen my males display an increase in health issues compared to the females. Even when I'm out and about at the local stores, I see plenty of each with their own problems.
Most likely, we just hear about male health issues more because they are, in fact, more popular. After all, nearly all of us keep males...but not all of us keep females. It's only natural that our posts would center around what we have the most of.