The smell is coming from bacteria in your pet’s mouth, which your pet will also be able to smell and taste. The bacteria will be:
Damaging the structures that hold teeth securely in the jaw.
Causing pain, especially as teeth start to loosen.
Causing infection. The low grade, constant bacterial load causes strain to your pet’s immune system and organ function, increasing the risk of other diseases.
Occasionally the bacteria can form an abscess around the tooth root, this is extremely debilitating and painful.