157: And Now the Punchline Has Been... Spiked!

Explanation
In the original strip, the lady's pet was non-anthropomorphic quadrupedal dragon. Here, it's replaced with Spike, from My Little Pony: Friendship is Magic. He'd likely consider being made into a pet degrading, never mind being put on a leash.

The image of Spike derives from the first season episode "Boast Busters". The title is a play on a line by Pinkie Pie in the episode "Owl's Well That Ends Well".

The author writes:
Original Hagar the Horrible strip: 1986-12-12.

Transcript
Lucky Eddie: Gee, that's a cute pet, isn't it? Hagar: Yeah... {The pet in question is Spike, held on a leash by a lady in a fur hat and coat. Spike is not enjoying this.} Hagar: but when they get bigger they're a lot of responsibility...

Trivia

 * This is one of the very few iToons strips to be derive from a physical release rather than digital, which would be the case if a digital version were difficult to get (e.g. being locked behind a paywall). Physical sources can be still be relatively easy to cleanly edit with apps such as GIMP and Photoshop, but less so with apps like MS Paint, with which this edit was presumably made, hence the large srcibble where the original dragon would be in this strip.