overriding 'virtual void ' c++ error

The following code gives me an error.

Error: overriding 'virtual void Animal::getClass()', where it says virtual void getClass() { cout << "I'm an animal" << endl; }

Error: conflicting return type specified for 'virtual int Dog::getClass()', where it says getClass(){ cout << "I'm a dog" << endl; }

Also, it says:

Class 'Dog' has virtual method 'getClass' but non-virtual destructor

#include 
#include 
#include 
#include 
#include
#include      // srand, rand
#include 

using namespace std;


class Animal{

public:
    void getFamily(){ cout << "We are animals " << endl;}

    virtual void getClass() { cout << "I'm an animal" << endl; }
};

class Dog : public Animal{


public:
    getClass(){ cout << "I'm a dog" << endl; }

};

void whatClassAreYou(Animal *animal){

    animal -> getClass();

}


int main(){

    Animal *animal = new Animal;
    Dog *dog = new Dog;

    animal->getClass();
    dog->getClass();

    whatClassAreYou(animal);

    whatClassAreYou(dog);


    return 0;
}