It's not selfish or cruel, but it's not likely to be practical. Countries all have different rules about bringing a dog with you from another country. In England, for example, the dog may have to quarantined for six months and that's a developed country!! Third world countries may have even more strict rules. Muslim nations may not allow you to bring a dog at all because they are considered unclean. In Vietnam, there has been a number of dognappings, so if you are going there that's a risk. Also, most airlines do not have good accommodations for dogs. There are many stories of dogs dying or getting lost on flights because they are treated like cargo.

A lot of countries have quarantine laws that will place your dog in kennels for long periods of time and some countries do not allow dogs in at all. I know how much you will miss your friend and I am sure he'll miss you too, but if you have a very responsible person to watch over him, truly think he'd be better off physically (and maybe mentally) at home. Some of your 3rd world places have absolutely deplorable conditions for people as well as dogs and most of them do not have the love that we in America and other civilized countries have.

Yes because he will have to be quarantined for a period of time then when you come back he will have to be quarantined again. If you are so afraid that you feel that he has to be your guardian then maybe you shouldn't go. You need to actually research what all he'll have to go through and all of the vaccinations that he'll have to have in order to travel as well as how long he'll have to be quarantined for all alone when you get into your first 3rd world country. If you just have to go then you need to look into getting a reliable escort or bodyguard that knows what to look out for.

don't know you can

lots of countries don't let dogs in

No not at all she or he will miss you dont leave it.