What this means
Bacteria living in the mouth build up on the teeth as plaque, which hardens over time. Bacteria gathered at the gum line cause inflammation: the gums redden, swell and bleed easily during brushing or when chewing something hard. This is by far the most frequent cause of bad breath, and it can be seen simply by lifting your dog's lip.
The character of the smell is worth noticing. A rotten, sickly-sweet smell alongside brown deposits and red gums points at the mouth. A smell like urine, or an unusually sweet, fruity smell, are signs of a different kind and must be mentioned to your vet even if the teeth look fine.
Look at how your dog eats, too. Chewing on one side only, dropping a mouthful, choosing soft food, pawing at the mouth or drooling all say the mouth hurts. Dogs frequently hide this and carry on eating, which is why the state of the teeth is often noticed late.
Tooth care at home works only while the gums are healthy and the teeth are not painful. If the gums are already red or bleeding, brushing will hurt and your dog will resist — an examination comes first, and the care habits are better started after it.
Possible causes
These are things that can cause this sign. It is not a diagnosis, and they are not equally likely for your dog.
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Plaque, tartar and inflamed gums
Bacteria built up on the teeth inflame the gum line. The gums redden, swell and bleed easily, and the smell strengthens gradually.
About the condition: Dental and gum disease -
A damaged or cracked tooth
A cracked tooth causes pain and local inflammation. The pattern is chewing on one side, with the smell coming from one side of the mouth.
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A foreign object in the mouth
A stick, bone splinter or thread lodged between the teeth causes a sudden smell and drooling. The dog may paw at its mouth and rub its face.
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Inflammation of the mouth lining or lip folds
Bacteria gather in damp lip folds, particularly in breeds with hanging lips. The skin there reddens, stays wet and starts to smell.
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Declining kidney function
When the kidneys no longer clear substances as they did, the breath can take on a urine-like note. Increased thirst and a poorer appetite often go with it.
About the condition: Kidney disease -
Metabolic changes
When sugar handling is disturbed, the breath can turn unusually sweet or fruity. Heavy thirst and frequent urination are usually seen alongside.
What else to watch for
These observations help your vet build the picture faster. Note down what you saw and when.
- What the smell is like: rotten, urine-like or sweet
- Whether the gums are red, swollen or bleeding
- Whether there are brown deposits on the teeth
- Whether your dog chews on one side or drops mouthfuls
- Whether drooling has increased
- Whether thirst, appetite or weight have changed
When to book a routine visit
Book a visit if the smell does not clear, if the gums are red or bleeding, if there are deposits on the teeth, if your dog chews on one side, or if the breath smelled of urine or was unusually sweet. The teeth are worth checking at the yearly health check even before you notice a smell.
Related conditions
Conditions whose entries mention this sign. The list is somewhere to read on, not a way to reach a diagnosis.
- Dental and gum disease Digestion and liver Dental and gum disease starts with plaque that hardens over time into tartar, and the bacteria multiplying beneath it cause inflammation of the gums. Left alone, the inflammation can damage the tissues and bone that hold the tooth in place, so teeth loosen and fall out. A sore mouth troubles a dog every day, and infection in the mouth can affect other organs too.
- Kidney disease Kidneys and bladder The kidneys filter the blood, remove waste from the body and help keep the balance of fluids and salts. When they are damaged suddenly, for example by poisoning or infection, or weaken gradually over a longer time, substances they should remove start to build up in the body. Long-term kidney changes can go unnoticed for a long time, because the healthy part of the kidneys takes over the work for a while.
- Liver shunt (portosystemic shunt) Digestion and liver A liver shunt is an abnormal blood vessel that carries blood from the intestines around the liver instead of through it. As a result, the liver cannot clear the toxic substances coming from the gut, and they enter the general circulation, affecting the brain and the whole body. A shunt can be present from birth or develop later because of other liver disease.
- Diabetes mellitus Hormones and metabolism Diabetes mellitus is a disease in which the body makes too little insulin or can no longer use it properly, so sugar cannot move from the blood into the cells and builds up in the bloodstream. The body's cells go short of energy even though the dog is eating enough, and blood sugar that stays high for a long time can harm various organs, such as the eyes. It is a long-term condition that needs ongoing monitoring together with a vet.
Body systems: Digestion and liver Kidneys and bladder Hormones and metabolism