It's a Thai racial slur and always has a negative intention.
You may not understand the negative implication, but it's there.
The missing of of the personal title (Kon, Pee, Lung, Khun, etc) before it is the giveaway.
Humans are always given a title, animals and things are not.
Back to the OP,
As you're not a racist Thai, why do you feel the need to insert that word in your sentences?
If you want to talk about foreigners, call them foreigners.