「あつくてとけそうだよ」かばのポポつぶやきました
I’m reading the free Kindle sample to the children’s book ポポくんのかきごおり which has an old fashioned shaved ice カキ氷 machine on the cover, something of interest these past few hot days.
Ｄoes かばのポポ mean '‘Hippopotamus’ or is this like a name, ‘ポポ the hippo’?
If this is the name construction, does it work for other animals? 狐のレイナード？Reynard the fox?
This is my first original forum post, I wish I knew how to check the formatting before releasing into the wild…
It’s the latter: Popo, the Hippo. 
河馬 【かば】 (n) hippopotamus
Notice the の as it makes it easier to separate the name from the noun. But, also as @Racing-Boat noted, the name itself is in katakana, while the word hippo is in hiragana.
As a sidenote, about DeepL. I’d rather go to a dictionary for inquires like this. It’s easy to search both the English word and Kaba on Jisho, to find the Japanese word, along with related words.
This is called an appositive の.
You can do the same thing with more mundane words.
ともだちのマイク my friend Mike
弁護士の山田さん the lawyer Mr. Yamada
I wasn’t aware of DeepL, thank you.
I’ve never heard popo used as an abbreviation for hippo. Can’t say I’ve heard ヒッポポタムス used either, just 河馬 as it’s an easier word for sure.
It could be a word play as you say though, though that’s present in the English word. Popo also seems to have some unrelated meanings/associations in Japanese.
Well, I mean, wordplay maybe, but also kids name things like that. “Kitty” the cat, “Doggy” the dog, etc.
That’s what I was thinking. Foxy the Fox, because I did a title search and found plenty of children’s books with ポポ in the title and a hippo on the cover. What made me unsure though was when I put it かばinto Google translate it came back with ‘hippopotamus’ but when I put in カバのポポ it still came back with ‘hippopotamus’. The google AI probably ran into the same situation I was 
To be fair, there’s no guarantee that a machine translator will pick up on the wordplay either. Dictionaries at least let you see multiple definitions for words you don’t know, whereas machine translators have to pick one translation and are often inaccurate or incorrect.