Where, if at all, should the line(s) be drawn?

[my miss storm cat]

I saw a name today and it made me wonder all over again about something...

I don't have pp's but there's a horse in the final at SA, Lisa Lulu, who I had asked about at the end of last year.

As far as I can remember she had 24 starts last year (I think that number is right).

Now I know they're race horses but what I'm wondering is is that too much?

One of the arguments I had on here quite a while ago was when an older horse was entered. I'm sure a few of you remember the tale of Alpena Magic.

http://www.ellisparkracing.com/events/?p=alpena

He was 17 at the time.

Should there be rules about how old is too old and how often is too often?

If they're pretty old or if they're entered too often should someone step in cause they're possibly accidents waiting to happen or is it wrong to inflict and enforce some set of rules on individual owners and trainers?