The Wikipedia article has since been deleted, with one user citing Puppy Channel Is Dog Tired, written in 2005, suggesting that the channel never existed:
Last week, an e-mail promoting the Puppy Channel rained down on nearly
every member of the Broadcasting & Cable staff and, we suspect, on
many, many others in the media.
The e-mail’s sketchy wording—the “big dogs” that attend the NCTA
convention this week “may have indicated the channel’s time might have
arrived”—reminded us that we’ve been hearing for nearly a decade about
the imminent launch of this channel devoted to the pairing of lovable
pups and nice music.
Dogs may be man’s best friend, but journalists can be a puppy’s
faithful companion. A sampling ...
Introducing The Puppy Channel: The Greatest Invention of the 1990s, written in October 2015, says it was never successful:
Unfortunately, The Puppy Channel never became its own cable network,
and the pilot [tv show] stopped airing sometime around the start of the new
millennium.