In the lesson for ‘homesick’, the following context sentence is given:
This puppy may be crying because he is homesick, but who cares?
When I typed 「こいぬ」into my IME (I’m using a Chromebook, if it matters), 仔犬 was the second result, behind what I expected the kanji to be, 子犬. So, is 仔 considered a reasonable substitute for 子? Does it have some sort of limit, like it can’t be used in 子供, or is limited to jukugo words, or something like that?