For what it's worth, I forward my complaint to Nesguy and
their reply.  I "unsubscribed" to the group, temporarily
(the 71,000-odd messages in the download to my computer had
me worried, so it seemed wise).  I'll check back in a day or
two to see if things have returned to normal.

My message:

(rec.pets.cats.anecdotes) has been maliciously flooded with
meaningless posts, similar to the one below.  When I say
"flooded", I mean that every time I sign on to the
newsgroup, there are 15,000-plus "unread" messages, all
gibberish, and with various ostensible points of origin.
None of the headers include any "complaint" address, and
anyway, it would take FOREVER to send abuse reports for tens
of thousands of posts a day.  I am assuming they're using
some sort of software that posts automatically - no one,
however mentally disturbed, has the time to type that many
posts!  Is there anything you guys can do at your end?

delete newsgroup messages unless they originate with me. The
total number of downloaded messages shown for the group is
(as of this moment) 71,162 so I begin to worry about my
computer's capacity.  This is one of my favorite newsgroups,
and the other regular posters are as frustrated with the
situation as I am.  I'm sure your equipment and knowledge is
superior to mine, can you help?

Their reply:

Thanks for the heads up. We've sent the details to SpamHippo
and should be off to clear that up momentarily.

Best regards,
Rich
rich@newsguy.com