Size Shape  Typical Breeds
20mm Disc Puppies, Cats, small breeds such as Chihuahua 
25mm Disc Medium breeds such as Dachshunds, Terriers, Miniature Poodles, Cockerpoo's, Schnauzers and spaniels
30mm Disc Large breeds such as Bulldogs, Collies, Dalmatians, Labradors and Retrievers