Do I have to
secure it in the car ?

Unbelievable but true: according to the
STVO ( Road Traffic Act) the dog in the vehicle is
is not a living being, but only load.
But even cargo must be secured in the
in the car.
So the question is not whether, but “how” a
dog should be secured.
There are various ways of doing this
possibilities,such as belts, partitions and dog boxes,
to name, just to name a few.
It is not only prevents the dog from
jumping around. The dog would be restrained and therefore
safe. But even with a harness that sits loosely, an animal can still be
be seriously injured. Just think of a braking in which the animal is first
thrown forward while accelerating,
and then is abruptly hold by the seatbelt.
According to the ADAC crash test, at a speed of
at a speed of 50 km/h,
a dog with 22 kg  would be shot forward with
25 times its weight, to the front.

With an unsecured dog
the consequences would be fatal, not only for the dog,
but also for the driver and passengers.
Since the dog would be like a projectile in the passenger compartment.
The injuries would be considerable.