The last one-horned Javan rhino in Vietnam was killed by poachers in 2010, effectively marking the end of a unique subspecies of Javan rhino.
That leaves us with the last subspecies of Javan rhino Rhinoceros sondaicus sondaicus in Indonesia. But the last census (2008) noted that fewer than 50 of the Indonesian subspecies exist in the wild.
Conservationists working for the Rescue Rhino Project plans to inject rhino horns with
"a dye which turns the horn brightly and irrevocably pink, kind of like the dye used in ink packs to secure money at a bank. That makes it useless as a prize or ornament, and even if the horn is ground to a fine powder, it'll still show up in an airport security scanner. Three separate GPS chips are implanted into the horn, kind of like this older project--it's worth mentioning here that a rhino's horn is made of keratin, just like your fingernails, and the animal feels no pain during any of this. And the dye has no adverse health effects on the rhino."