Dogs fighting wildlife crime at Heathrow Airport
10 February 2014 Last updated at 08:09 GMT
World leaders will meet this week to work out how to stop the illegal wildlife trade.
Campaigners say hunting animals like elephants and rhino has reached an all-time high.
In the UK an agency called Border Force is in charge of stopping criminals from illegally transporting endangered plants and animals in and out of the country.
Newsround's Nel spent a day with them and found out how dogs help detect illegal items.