Bad Breath (Halitosis)
口臭 (koshu)
Definition
A strong smell from a dog's or cat's mouth, most often produced by bacteria living in plaque and tartar, and sometimes reflecting something further down in the body.
Key points
- Most bad breath in dogs and cats traces back to bacteria in plaque and tartar on the teeth
- Bad breath is common, but common is not the same as normal, and it is usually a sign of something
- A smell that appears suddenly, or that is sweet or metallic, is a reason to see a veterinarian
- Brushing works on plaque. Tartar has to be removed at the practice
What causes bad breath in dogs and cats?
The usual source is the mouth. Bacteria settle on the teeth in a soft film, that film hardens into tartar, and the bacteria living in it release sulphur compounds that carry a strong smell. Dental disease is one of the most frequently diagnosed conditions in adult dogs and cats, which is why bad breath is so widespread. Widespread, though, is not the same as normal. It generally means something is going on.
The connection further down
The mouth is the start of the digestive tract, and the bacteria there are swallowed continuously, which is why oral bacteria and the gut microbiota are discussed together. The link is a subject of active research rather than a settled account, and it is not a reason to look past the teeth when the teeth are the obvious candidate.
Breath can also reflect the body more broadly. A sweet or fruity smell, a smell resembling ammonia, or breath that changes at the same time as thirst, appetite or weight are the ones veterinary sources single out, because they can relate to organs rather than to the mouth. These are appointments, not home projects.
What owners can do
Daily brushing with a toothpaste made for animals is the measure with the most behind it, and starting slowly, over weeks, is how most animals come to accept it. Human toothpaste is not used, since it is not meant to be swallowed. Once tartar has formed, a cleaning under veterinary care is the only way to remove it, and breath usually improves markedly afterwards.
If the breath came on suddenly, or if the animal is pawing at its mouth, dropping food, or eating on one side, book an appointment rather than working on the smell.
This entry shares general knowledge and is not veterinary advice. It is not intended to diagnose, treat or prevent any condition. If you have concerns about your dog or cat, please consult your veterinarian.
FAQFrequently asked questions
Why does my dog's breath smell bad?
In most cases bacteria in the film on the teeth are producing sulphur compounds, which is what you smell. Dental disease is extremely common in adult dogs and cats, and breath is often the first thing an owner notices.
Will brushing my pet's teeth fix bad breath?
Brushing disrupts plaque, which is the soft film bacteria live in, and it is the single most useful daily habit. Once plaque has hardened into tartar a brush no longer removes it, and a veterinary cleaning is what is needed.
My cat's breath suddenly smells different. Should I worry?
A sudden change is worth a veterinary appointment. A sweet or fruity smell, a smell like ammonia, or breath that changes alongside drinking, appetite or weight are the ones described as needing prompt attention, because they can point to something other than the mouth.
Do dental treats and water additives work?
Some products have been assessed by independent bodies for their effect on plaque and tartar, and those are the ones worth looking for. None of them replace brushing or a professional cleaning when tartar is already present.