There are three types of Siamese cats. There is the Applehead or Traditonal Siamese, the Old Style or Classic Siamese, and the Modern, Wedgehead or Extreme Siamese. Physical characteristics distinguish each category of cat and breeders classify each cat by its body shape.
The Applehead or Traditional Siamese cats were the first Siamese cats imported from Siam. Traditional Siamese cats are characterized by their round, muscular bodies and round faces. Like Traditional Siamese, Old Style or Classic Siamese cats have large bones, but their bodies are longer and slimmer. The face shape is also more triangular. Modern Siamese or Wedgeheads are the most common type found in cat shows. They have smaller bones than the Traditional and Classic cats and are generally longer and thinner. The muzzle is longer, and the nose is straighter.
Variations of the Siamese cat morphology have been achieved through breeding. This practice is not always healthy and may result in serious medical complications for the cat. In some cases, the offspring do not survive. Health problems are more common in the Modern or Wedgehead, and the trend to make the body smaller is thought to be responsible for most of these issues. These cats are more likely to experience organ failure, immune system defects and shorter life spans.