Vets looking after a pair of rhinos at Chester Zoo have had their jobs made easier by some new technology.
Because rhinos are so big, and have skin up to 2.5cm thick, it's always been hard to listen to their heartbeat using normal equipment - until now.
But now a new stethoscope has been made that is so good at picking up sounds that vets can hear through rhino skin.
The stethoscope makes looking after the mother and daughter rhinos, called Emma and Basheera, much easier and safer.
Rhinos are very big, so it's dangerous for vets to get too close to them.
So normally, big animals like rhinos and elephants need to be knocked out using drugs before they can be examined.
This new stethoscope could make the examinations a lot easier.
This means vets could check up on rhinos more often, and hopefully help keep more of the rare animals alive.