Can you imagine what this smells like? Wow! Bad breath is "bad" because it contains volatile organic compounds that come from the bacteria that are present on the teeth and more importantly in the gum pockets around the teeth. Essentially, it is the smell of rotting flesh! One would think that this degree of trouble would be a rare event, but sadly it is very common.
The first time in your pet's life that you may encounter bad breath is at the time of teething. The inflammation of the gums from the stretching and tearing of the gums as the larger adult teeth break through leads to a moderate amount of gum infection. Then, for a year or two most pets are free from dental disease. by the age of three 95% of pets have clinically significant gum disease. So bad breath is not an optional thing to deal with, it is the sign of a serious health disorder!
Since gum infection is the primary cause of bad breath, monitoring your pet's breath is a good way to monitor if you are keeping ahead of the gum disease. For mild gum disease, brushing teeth or the oral hygiene solution in the water may be enough to slow it down or even stop the problem. For advanced gum disease, a dental scaling of the calculus above and below the gum line is required. The curretting of the gum pockets is of primary importance. Gum disease exists in these pockets and then the plaque and calculus come secondarily. That is why "anesthetic free" dental cleaning is such a problem. You may be able to clean the large chunks of calculus from the surface of the teeth while your pet is awake, but removing the calculus and plaque from under the gum surface is the treatment that is needed to resolve the gum disease.
When the gum pockets are greater than 3 mm deep, a surgical procedure to remove the excessive gum may be performed. This removes the "home" for the anaerobic bacteria that are causing all the problems. One of the reasons I like to use products that provide extra oxygen in these areas of gum disease and since anaerobic bacteria "hate" oxygen, we end up with a more normal environment and thus a normal population of good bacteria are preserved. Some of the oral rinses and water supplements available contain chlorhexadine, which kills all types of bacteria. These may be helpful for short term control but long term they can lead to superbug formation, bacterial resistance.
A healthy mouth is a fresh smelling mouth. If there is an odour, there is a problem. In fact, there are now chemical sensor strips available to assess how much periodontal infection is present. A regular habit of brushing teeth that is supplemented by water additives and special dental diets can prevent the problem from developing in the first place. Once it is there, a professional cleaning will be required with possible extractions to leave your pet with a healthy mouth for you to maintain.