The 'Super Pets', debuted with 'Krypto' the superdog in DC's "Adventure" #210 (1955).
'The Legion of Super-Pets' debuted in "Adventure Comics" #293 (1962).
The original Legion roster included Krypto, 'Comet' the superhorse, 'Streaky' the supercat, 'Beppo' the supermonkey and 'shape-shifter' 'Proty II'.
Significant appearances include "Adventure" #322 (July 1964) when 'Proty II' is initiated into the team and "Adventure" #343 (April 1966), when the pets help the 'Legion of Super-Heroes' battle the 'Luck Lords'.
"Adventure" #364 (January 1968) was titled, "The Revolt of the Super-Pets!"
"...when the 'Justice League' are kidnapped, 'Krypto', the alien super-dog belonging to 'Superman', forms a team of shelter pets with super powers...
"...including 'Ace' who becomes super strong, a pig named 'PB', who can grow to giant size, a turtle named 'Merton', who becomes super fast and a squirrel named 'Chip', who gains electric powers..."
Click the images to enlarge...