Dog Name & Breed - my solution

using System;

public interface IDog
{
    string Name {get;}
    string Breed {get;}
}

public class Dog: IDog
{
    public string Name {get;}
    public string Breed {get;}

    public Dog(string name, string breed)
    {
        this.Name = name;
        this.Breed = breed;
    }

    public Dog()
    {
    }

    public override string ToString()
    {
        string s;

        if(this.Breed != null && this.Name != null)
        {
           s = string.Format("The {0} dog {1} said BARK!",this.Breed,this.Name);
        }
        else
        {
            s = null;
        }
        return s;
    }
}

public class Program
{
    public static void Main()
    {
      string breed = "poodle";
      string name = "Angel";

        Dog poodle = new Dog(name,breed);
        Console.WriteLine(poodle);

        Dog shephard = new Dog();
        Console.WriteLine(shephard);
    }
}