From Wikipedia.

Roger Waters - Bass guitar, vocals
David Gilmour - Vocals, acoustic and Fender Telecaster electric guitars
Richard Wright - Fender-Rhodes piano, Hammond organ, Mini-Moog Synthesizers, ARP String Synthesizer, backing vocals
Nick Mason - drums, percussion.

Dogs are used to represent the megalomaniacal businessmen who destroy themselves and those around them by obsessing over their egos and their careers. A number of comparisons are made and metaphors used to show how close these businessmen are with dogs, for example “Got to be able to pick out the easy meat with your eyes closed” the meat representing deals and opportunities for the businessmen. It is a long, increasingly haunting song at over seventeen minutes.

During their tour in 1974 Pink Floyd played three new songs in the first half of the shows, followed by the whole of the The Dark Side of the Moon album. Those three new songs were “You Gotta Be Crazy” (which would later become “Dogs”), “Shine On You Crazy Diamond” and “Raving And Drooling” (which would later become “Sheep”).

During 1974 performances of “You Gotta Be Crazy”, David Gilmour would sing the song in a faster speed than the versions on the 1975 US tour and the Animals album. “You Gotta Be Crazy” was about the problems one had to deal with in life. The lyrics were modified by the time the song was played live in 1975 and then the lyrics changed again when recording Animals.

Both “You Gotta Be Crazy” and “Raving And Drooling” were originally planned to be on the album following the tour Wish You Were Here, but the plans were changed (which later became a point of dispute between Gilmour and Waters, as an early sign of their later animosity) and they both ended up in different forms on Animals.

Lyrics:-

You gotta be crazy, you gotta have a real need.
You gotta sleep on your toes, and when you’re on the street,
You gotta be able to pick out the easy meat with your eyes closed.
And then moving in silently, down wind and out of sight,
You gotta strike when the moment is right without thinking.

And after a while, you can work on points for style.
Like the club tie, and the firm handshake,
A certain look in the eye and an easy smile.
You have to be trusted by the people that you lie to,
So that when they turn their backs on you,
You’ll get the chance to put the knife in.

You gotta keep one eye looking over your shoulder.
You know it’s going to get harder, and harder, and harder as you
get older.
And in the end you’ll pack up and fly down south,
Hide your head in the sand,
Just another sad old man,
All alone and dying of cancer.

And when you loose control, you’ll reap the harvest you have sown.
And as the fear grows, the bad blood slows and turns to stone.
And it’s too late to lose the weight you used to need to throw
around.
So have a good drown, as you go down, all alone,
Dragged down by the stone.