The driver who is said to have tied a dog to his Porsche and then drove around until it was dead is being held by police.
Although the Beagle-Collie cross was taken to the vet, pet medication was not administered, as it was already dead.
It had been dragged from a car park in Brighton along the A27. Its body was dumped in a layby and police constable Scott Walters said it suffered "horrific injuries".
The man’s solicitor released a statement to the Argus, claiming he was not aware that the animal was tied to the car and that it was a "terrible set of circumstances".
He said the dog had got loose while being walked on an extending lead and the cord had become tangled in his exhaust system.
According to the news provider, the statement said: "The driver was completely unaware of what had happened.
"He stopped to check his car several times because he heard a sound and thought there might be something wrong with his brakes. However he did not see the animal behind him.
"My client is a dog lover and is completely devastated by what has happened."