I grew up in a bilingual English/Hebrew house and I think that wholehearted is the correct definition. It's also my son's name so I take the analysis seriously (maybe a bit too much, LOL). Caleb definitely does not mean dog in Hebrew, but when two words have the same root in Hebrew there is a connection. So the theory I understand is that Caleb has a second definition of having attributes like a dog.
In other words, people named Caleb have a name that means Whole-Hearted and have the characteristics of loyalty, boldness, friendship, etc., things that we associate with man's best friend.
P.S. - I understand that in the comments, Caleb is discussed as Whole-Hearted, but in reference to the comment: "Etymologically "whole-hearted" would be impossible since the name would have to be כֻּלֵּב Kulleb to have that meaning". The wrong vowel was called out and therefore the conclusion is inaccurate. In the quote above, there are three diagonal dots (a kibbutz) under the cuff (equivalent for "C"), which is not how Caleb, nor how Kol (whole/all) are spelled in Hebrew. Kol, meaning whole/all, is spelled with a cholam which is a dot in the upper left corner of the cuff for the "C" (כֹּל).
Caleb is spelled with a kamatz (looks like a partial plus sign), a different vowel, but gives the same sound when the words are put together (כָּלֵב). The correct pronunciation of heart in Hebrew is Kol (and heart is Laiv). Caleb is pronounced Kolaiv. So when spelled correctly and pronounced correctly, it's entirely possible (and likely) that Whole-Hearted is the correct definition.
Just arguing the vowel in the reference. I give full acknowledgment that in the conversation, people recognize the meaning as whole-hearted.
Side note: The Hebrew word for dog is pronounced Kelev, not Keleb. The Hebrew letter for "B" alternates between the b and v sounds depending on if there is a dot in the center or not. Kind of like how an h changes the s or c sounds in English.