What does the term "screwed the pooch" mean, and what is its etymology?

"Screwed the pooch," meaning "made a terrible mistake," is a
cleaned-up paraphrase that author Tom Wolfe popularized. Wolfe's book
"The Right Stuff," which dealt with the early years of America's
manned space program, used the phrase "screwed the pooch" in
describing a calamitous error made by Mercury Astronaut Gus Grissom:

"But now - surely! - it was so obvious! Grissom had just screwed the
pooch! In flight tests, if you did something that stupid, if you
destroyed a major prototype through some lame-brain mistake such as
hitting the wrong button - you were through! You'd be lucky to end up
in Flight Engineering. Oh, it was obvious to everybody at Edwards [Air
Force Base] that Grissom had just f*cked it, screwed the pooch, that
was all."

(from page 230 of "The Right Stuff," by Tom Wolfe)

The original military term (with an asterisk which I've substituted
for a vowel) was "f*cked the dog," which generally referred to
military men goofing off on the job, rather than to catastrophic
errors:

"Screw the Pooch
The phrase screw the pooch, meaning to mess up, commit a grievous
error, was made famous in Tom Wolfe's book The Right Stuff. The phrase
is a euphemism from US military slang. The original expression was
f*ck the dog and meant to waste time, to loaf on the job.

F*ck the dog dates appears in print for the first time in 1935, but in
1918 another euphemistic version, feeding the dog, appears. The
original sense dates to 1918. Over the decades, the meaning shifted to
the current sense and the screw the pooch wording took the place of
the original phrasing."

Etymologies & Word Origins
http://www.wordorigins.org/wordors.htm

"The phrase 'screw the pooch' itself was derived from an earlier
phrase that was quite familiar to those of us in the service in WW2. I
was a Fire Control Computer technician (Fire Controlman) in the US
Navy 1944-1946.

Anyone who has ever been in the military has spent an inordinate
amount of time in a 'stand-by' formation waiting for someone to get
the orders to start some activity. Many man-hours were spent in an
activity that was commonly known as 'Effing the dog.' [Note: They
didn't really say, 'Effing,' but I'm sure you can figure it out.] Back
home in civilian life this was cleaned up to the slightly more
acceptable 'screwing the pooch."

The LangaList
http://www.langa.com/newsletters/2002/2002-03-21.htm

Google search strategy:

Google Web Search: "screw OR screwed the pooch" meaning OR origin OR etymology
://www.google.com/search?hl=en&ie=UTF-8&q=%22screw+OR+screwed+the+pooch%22+meaning+OR+origin+OR+etymology

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Best regards,
pinkfreud

Exactly what I was looking for.  Plus, now I know of more resources to
find out other answers on my own.  Thank you.