Rex had a run of 46 issues, which had two stories each of him, plus one backup, almost always Detective Chimp, another good concept let down by really, really bad art. Though I suppose any art's going to look bad next to Alex Goddamn Toth.

After that he went into limbo until a silver-age retelling of the formation of the Justice League, where he made a bit cameo. Congorilla got more screentime. While Bobo got a panel in Crisis, Rex is absent, unless he's in the background somewhere and I never spotted him.

He got a story in Secret Origin that parodied Captain America's origin, and a "Whatever happened to..." story from DC Presents.

He and Bobo appeared in a two-part Lantern/Flash crossover where he fought and beat Gorilla Grodd, and then a several-part story in Flash where he beats Grodd yet again, though it's written a lot more grim'n'gritty. In both of these stories he could talk.

He was a recurring character in Superboy and the Ravers, this time as the dog of Hero Cruz. He can't talk. Oops.

After that, I'm pretty sure there was nothing until Infinite Crisis set up the Shadowpact, which he was tied to loosely until that series ended. Supposedly he's still living out of the Oblivion Bar with Bobo.

Pooch has had even less luck.

Pooch is Rex's brother, and it is implied he was subject to the same testing as Rex. Like Rex, he served in WWII, but unlike Rex, he never made it out.

He appeared in Gunner & Sarge as a supporting role, whereas Rex was always the star. Still got plenty of great moments, though. As the artists changed, so did Pooch's color. I think in the most issues he was shown as being white like his brother, but in his final canon appearance he was brown.

After Gunner & Sarge ended and the Losers started, Pooch was nowhere to be found. Which is odd, because every comic resource will tell you Pooch served with the Losers. He was in the Losers Crisis special, he's in New Frontier with them, the Vertigo Losers have a Pooch, etc. He made a cameo in a Losers story where they explained why he wasn't around (Pooch isn't a loser), and some backup stories were flashbacks to the Gunner & Sarge that included Pooch, but he was mostly absent.

Then as I mentioned he appears in the Crisis special, where he gets his own story complete with thought bubbles, and then he dies saving Easy Company with Gunner and Cloud, strafed by an airplane. He appears in New Frontier and dies again, by dumbass Cloud hitting a tripmine. He was white in that one. Oops.

Streak the Wonder Dog is the conceptual forerunner to Rex and Pooch, which proved dogs can save a failing comic. It's nerd legend that Alan Scott became a dog's sidekick in his comic's final days. His very few appearances are spread between Green Lantern, All-American and Sensation. Oddly enough Sensation was a Wonderwoman comic and Streak's backup stories didn't have a damn thing to do with Alan Scott. For his few appearance he does get an origin story, which was pretty nifty.

So he doesn't look much like a german shepherd and in fact looks more like a corgi, and Toth did in fact draw these so you can't say he didn't research what the dog was supposed to look like, but come on. His stories are either pre-war or during, it would be such a beautiful retcon to say he's a german shepherd and Alan Scott gave some puppies away for K-9 training as per All-Star Squadron obligations he felt he had.

But this is a thread about Rex. And brother, I love me some Rex. His original run was written entirely by Robert Kanigher, and his subsequent appearances have not come close to capturing the sheer balls-to-the-wall insanity that he was famous for. One day he could be saving a little boy from a barn fire and the next he could be saving entire alien civilizations.

As for why he's rarely used in modern comics, I have three explanations:

1. No good writer has given him a second thought, because they've never heard of him.

2. They HAVE heard of him, and out of respect for the fact that the modern age of comics hasn't retroactively raped his childhood or stuffed his wife in the fridge yet, they've handled him with kid gloves.

3. Most comic artists, only employed for their ability to reliably draw perfectly muscled thirty-somethings, have no goddamn clue how to draw a dog. Or a chimp. Or anyone under the age of 18.

Actually, I just remembered. There's an issue of Teen Titans where Hero Cruz considers becoming a Titan. A tryout story? Anyway, I think he had Rex with him at the time. I don't have that issue, so if someone has it....

Looked it up, it's The Titans Secret Files #2