As judges at dog shows well know, distinguishing between a chihuahua and a mastiff is a difficult, perplexing and confusing job. The tricky task is somewhat easier if the two animals are side by side, but with study and practice, the distinction can be made even when the dogs are viewed one by one.
There are two subtle points of distinction:
1) The nose. The mastiff’s nose is blunt, while the chihuahua’s is pointy.
2) The ears. The mastiff’s ears are floppy. The chihuahua’s are sharp, upright and pointy.
If, after examing ears and nose, you are still in doubt, there is yet another method of distinguishing between a mastiff and a chihuahua. This technique involves two steps.
1) Sit on the dog.
2) Arise and examine the dog.
If the animal is alive and well, you are dealing with a mastiff. If the dog is not, then what you had was a chihuahua.